Abstract
The Zhongwunongshan Structural Belt (ZWSB) locates between the Olongbruk Microblock of North Qaidam and the South Qilian Block in China, and it has important implication for understanding the tectonic significance of North Qaidam. Nowadays, there are few discussion on the Caledonian tectonothermal events of the Zhongwunongshan Structural Belt, and there exist different opinions on provenance and tectonic environment of the Zhongwunongshan Group in the ZWSB and its adjacent North Qaidam. In this study, a comprehensive analysis of the detrital zircon geochronological research was carried out on the Zhongwunongshan Group. The detrital zircon U-Pb dating results showed two major populations. The first was Neoproterozoic (966-725 Ma) with a ∈Hf(t) = −15.9 to 9.5, and the other was late Early Paleozoic (460-434Ma) with a ∈Hf(t) = −9.6 to −3.1. In combination with previous research, the dominated provenances were found to be the Neoproterozoic granitic gneiss of the Yuqia-Shaliuhe HP-UHP metamorphic belt and the late Early Paleozoic granite of the Tanjianshan ophiolite-volcanic arc belt in North Qaidam. The Zhongwunongshan Group was deposited in the back-arc sedimentary basin related to the Caledonian collisional orogeny during Middle Silurian-Early Devonian (434-407.9 Ma).
1 Introduction
The Zhongwunongshan Structural Belt (ZWSB) is a northwest-extending structural belt located between the Olongbruk Microblock of North Qaidam and the South Qilian Block [1, 2] (Figure 1). The ZWSB is separated from the South Qilian Block to the north and the Olongbruk Microblock to the south by the Qinghai Nanshan Fault and the Southern Zhongwunongshan Fault, respectively. It extends westward to the Altun Fault, and divides between the West Qingling and South Qilian in the east. Therefore, the geological position of the Zhongwunongshan Structural Belt is significant. It is generally believed that the Zhongwunongshan Structural Belt is a Hercynian-Indosinian tectonic zone developed on the Caledonian block jointly constructed by the Olongbruk Microblock of the North Qaidam and the South Qilian Block [5, 6, 7]. At present, there are few data reported the Caledonian tectonic thermal events and evolution of the ZWSB.
The Zhongwunongshan Group is the most important and widely exposed formation in the ZWSB and adjacent North Qaidam. Therefore, the Zhongwunongshan Group is determined to be the ideal object for the tectonic research of the ZWSB. The previous authors carried out a certain research on Zhongwunongshan Group, and most of them believe that it deposited in the Late Carboniferous rift [8, 9, 10]. However, other geologists have had different viewpoints about the tectonic environments and basin types of the Zhongwunongshan Group deposited in. There are two primary views about tectonic environment and basin type: (1) The Zhongwunongshan Group deposited in a stable passive continental margin basin, which irrelevant to plate subduction and collision [7, 10, 11]; and (2) Due to plate subduction and collision, the sediments deposited in the back-arc sedimentary basin along the North Qaidam active continental margin [9, 12, 13]. A consensus in the detritus provenance has also not been reached. Some scholars suggest the provenance was located in the uplift terrane along the southern margin of the South Qilian Block to the north [11, 14, 15], but the others hold the opinion that, the southern part of North Qaidam provided sediments northward [9, 13]. Meanwhile, Geologists also held different opinions about the stratigraphic age of Zhongwunongshan Group. Some believed the strata deposited in Late Carboniferous as indicated by the fusulinids and corals [16]. However, the fossils identification were challenged because of their limited occurrence and metamorphic recrystallization.
Clastic rocks contain lots of useful information, including the material composition and tectonic environment of the source area, and the crustal evolution in the early geological history [17, 18]. The zircon geochronology has been widely used to reveal the petrogenesis of clastic rocks [19, 20], and to reconstruct the characteristics and tectonic environment of source areas [20, 22, 23, 24]. Since sandstone and mudstone are relatively homogeneous and have high level of trace element, they become the first choice for geochemical and chronological studies [21, 25, 26]. Epimetamorphic clastic rocks have also been widely used to study the petrogenesis and tectonic environments of source areas [20, 27]. Based on the previous research with the new geochronology analysis of the Zhongwunongshan Group clastic rocks, this paper aims at providing new data to reconstruct the provenance and tectonic setting of Zhongwunongshan Group, and attempting to find the geological records of the Caledonian tectonic thermal events in order to provide a reasonable explanation for the aforementioned problems.
2 Geological background
Recent studies have well demonstrated that the North Qaidam Structural Belt (NQSB), bounded by the South Qilian Block to the north and Qaidam Block to the south (Figure 1), is a composite tectonic orogenic belt with multi-stage orogenic processes [2, 28]. The NQSB consists of the Shaliuhe-Yuqia high pressure-ultrahigh pressure (HP-UHP) metamorphic belt, the Tanjianshan ophiolitevolcanic arc belt, the Olongbruk Microblock (Figure 1b), from south to north, in view of the significantly diverse geological composition and tectonic evolutionary history [28, 29]. The complex tectonic composition indicates that the sub-tectonic units that make up the NQSB underwent different tectonic evolutionary phase predating the pre-Devonian, including the Paleoproterozoic (2400–1800 Ma) continental crust formation [2, 28]; Neoproterozoic (1030–750 Ma) magmatic activities related to Rodinia supercontinent convergence and breakup [30, 31]; early Paleozoic (542–434Ma) magmatism and HP-UHP metamorphism by oceanic crust subduction followed by collision associated continental deep-subduction [3, 32]. The continental deep subduction marked the assembly of Olongbruk Microblock and the Qaidam Block. Subsequently, the NQSB evolved into the post-orogenic stage indicated by the rifting molasse of the Upper Devonian Maoniushan Group.
The Shaliuhe-Yuqia HP-UHP metamorphic belt is the northern border separating the Qaidam Block from the NQSB (Figure 1b). The belt is predominantly composed of Neoproterozoic-Early Paleozoic granitic gneiss (1011–434Ma) and metamorphic supracrustal rock, with minor sporadically exposed eclogite (1000–800 Ma) [29, 33]. The Tanjianshan ophiolite-volcanic arc belt, to the north of HP-UHP metamorphic belt, is dominated by widespread Early Paleozoic intermediate-basic volcanic (486–450 Ma) and pyroclastic rocks with ophiolite complex, which are intruded by granitic intrusive rocks (465–434 Ma) [4, 34] (Figure 1b). The Olongbruk Microblock has an early Paleoproterozoic crystalline basement including the ~2400 Ma Delingha granitic gneiss and the ~1800 Ma Khondalite– like supracrustal rocks (Figure 1b). Above the basement are a series of unmetamorphosed sedimentary successions that were discontinuously deposited from late Paleoproterozoic to Cenozoic [4, 8, 11, 34, 35, 36].
This study focuses on the ZWSB and the adjacent North Qaidam (Figure 1b). The ZWSB widely outcrops the Upper Carboniferous Zhongwunongshan Group comprising carbonate dominated sedimentary successions with some volcanic interlayers, which are overlain by Permian-Triassic shallow marine clastic rocks and carbonates [6, 8, 14] (Figure 1c). The Zhongwunongshan Group have been further subdivided into two lithostratigraphic units. The lower section is predominately composed of gray green phyllite and sandy slate, with minor medium-basic volcanic layers and limestone lenses,whichwere deposited in the neritic shelf environment. The upper unit mainly consists of gray white banded limestone and dolomitic limestone with gray green intermediate-basic volcanic interlayers, typically formed in sublittoral platform environment (Figure 2).

Stratigraphic column of the Zhongwunongshan Group
In this study, two samples (KDLG1505 and BLG1505) were collected from the sandstones of Zhongwunongshan Group exposed in the Baluogenguole (BLG) and Kendelonggou (KDLG) areas (Figure 1c), respectively.
3 Analytical Methods
3.1 Zircon geochronology analysis
The detrital zircons were separated using a conventional heavy liquid and magnetic separation techniques, and then further purified by handpicking under a binocular stereoscope. Subsequently, the grains were mounted in epoxy, and polished to expose the cores of the grains. Cathodoluminescence (CL) images were obtained for all zircons prior to analysis, in order to characterize the internal structures and to choose potential sites for in the in situ U-Pb dating and Lu-Hf analyses.
This zircon U-Pb dating was conducted in the Key Laboratory of Metallogeny and Mineral Assessment of the Ministry of Nature Resources, which is located at the Institute of Mineral Resources of the Chinese Academy of Geological Sciences. The zircon geochronology was performed by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS), on a Finnigan Neptune equipped with Newwave UP213 laser ablation system, with an ablation spot diameter of 30 μm, frequency of 10 Hz, and energy density of approximately 2.5 J/cm2. Helium was used as the carrier gas. Zircons SRM610, Plesovice, and 91500 were used as the external standards for correcting the mass discrimination and isotope fractionation. The detailed analytical conditions are described in [37]. An ICPMSData-Cal program was used for the data processing [38], and the Concordia diagrams were obtained using an Isoplot4.0 routine [39]. Therefore, in this study a maximum of 80 individual zircon grains were selected randomly from each of the samples. Among the 80 grains, we excluded zircon age analyses with >10% discordance for interpretation.We report the ages derived from 206Pb/238U for < 1000 Ma and 207Pb/206Pb for = 1000 Ma. Visualization of U-Pb zircon ages is achieved using Isoplot 4.0 [39] and Density Plotter program [40].
3.2 Zircon Hf isotope analysis
The Zircon in situ Lu-Hf analysis was completed in the State Key Laboratory of Continental Tectonics and Dynamics of the Institute of Geology, Chinese Academy of Geological Sciences, utilizing a Neptune Plus MC-ICP-MS instrument, and a Complex pro.193nmlaser-ablation system. The ablation spot diameter was 44 μm. The global zircon standard GJ-1 was taken as the reference material, and the analytical points were the same as those of the U-Pb dating. The detailed operating conditions for the LA-MC-ICP-MS and calibration strategy followed those used by [41]. The LA-MC-ICP-MS analyses of the zircon standard GJ-1 during the analytical process achieved the 176Hf/177Hf ratio of 0.282015 ± 8 (2σ, n = 10), which was identical to the literature values within error [42].
4 Results
4.1 Zircon U-Pb dating
The zircon grains from sample BLG1505 range in size from 50 to 100 μm with length/width ratios of 2:1–1:1. These zircons generally display sub-angular to rounded morphology. In CL images, most zircon grains have clear oscillatory zonings, with few zircons showing week zoning or being structureless (Figure 3). All dated zircons show high Th/U ratios of 0.26–2.05, low LREE/HREE (<1) ratios and REE+Y content (<1%), positive Ce and negative Eu anomalies (Table 1), which jointly indicate a magmatic origin [43, 44]. The sample BLG1505 yields 67 concordant U-Pb ages varying from 2456 Ma to 634 Ma with one major age cluster (Table 1, Figure 4a). The most prevailing age cluster of 925–725 Ma contains 53 data and defines two age peaks at 831 Ma and 804 Ma. Additionally, few zircons of Paleo- and Mesoproterozoic age are also present, with subordinate peaks at 2398 Ma and 1746 Ma (Figure 4b).

Cathodoluminescence images (CL) of the representative analyzed detrital zircons and their corresponding U-Pb ages from the Zhongwunongshan Group sandstone samples (BLG1505 and KDLG1505). The open circles represent the positions of ablation pits
Microelement eigenvalues of zircons from the Zhongwunongshan Group sandstones
Sample Spot | Σ REE+Y | δEu | δCe | LREE/HREE | Sample Spot | Σ REE+Y | δEu | δCe | LREE/HREE |
---|---|---|---|---|---|---|---|---|---|
Sample BLG1505 | Sample KDLG1505 | ||||||||
BLG1505-1 | 984.65 | 0.30 | 154.39 | 0.10 | KDLG1505-01 | 872.27 | 0.84 | 1.13 | 0.43 |
BLG1505-2 | 2242.89 | 0.48 | 56.63 | 0.03 | KDLG1505-02 | 870.60 | 0.23 | 56.28 | 0.04 |
BLG1505-3 | 1227.22 | 0.36 | 18.87 | 0.03 | KDLG1505-03 | 1237.64 | 0.40 | 78.44 | 0.08 |
BLG1505-4 | 3122.88 | 0.31 | 5.58 | 0.02 | KDLG1505-04 | 1364.93 | 0.36 | 3.68 | 0.13 |
BLG1505-6 | 935.13 | 0.50 | 1.37 | 0.11 | KDLG1505-06 | 1165.79 | 0.32 | 3.50 | 0.15 |
BLG1505-7 | 1891.89 | 0.67 | 7.39 | 0.02 | KDLG1505-07 | 1454.27 | 0.24 | 4.65 | 0.04 |
BLG1505-8 | 1956.24 | 0.36 | 85.73 | 0.05 | KDLG1505-08 | 957.66 | 0.23 | 56.28 | 0.04 |
BLG1505-9 | 2541.56 | 0.60 | 12.42 | 0.04 | KDLG1505-09 | 2154.00 | 0.28 | 4.97 | 0.05 |
BLG1505-10 | 1732.07 | 0.70 | 57.82 | 0.02 | KDLG1505-10 | 1296.68 | 0.36 | 3.68 | 0.13 |
BLG1505-11 | 1137.40 | 0.50 | 33.45 | 0.02 | KDLG1505-11 | 2154.00 | 0.28 | 4.97 | 0.05 |
BLG1505-12 | 3328.52 | 0.25 | 208.57 | 0.04 | KDLG1505-12 | 3307.58 | 0.11 | 1.05 | 0.12 |
BLG1505-14 | 1479.85 | 0.49 | 46.33 | 0.03 | KDLG1505-14 | 914.13 | 0.23 | 56.28 | 0.04 |
BLG1505-15 | 3899.46 | 0.16 | 1.07 | 0.09 | KDLG1505-15 | 655.49 | 0.27 | 26.48 | 0.04 |
BLG1505-16 | 836.95 | 0.30 | 26.55 | 0.06 | KDLG1505-16 | 1574.60 | 0.12 | 69.11 | 0.03 |
BLG1505-17 | 852.27 | 0.52 | 76.20 | 0.14 | KDLG1505-17 | 1508.14 | 0.44 | 11.42 | 0.06 |
BLG1505-18 | 3793.98 | 0.10 | 14.83 | 0.04 | KDLG1505-18 | 1099.85 | 0.25 | 58.76 | 0.04 |
BLG1505-19 | 1901.71 | 0.41 | 98.29 | 0.03 | KDLG1505-19 | 1724.24 | 0.14 | 1.33 | 0.10 |
BLG1505-20 | 1471.52 | 0.11 | 132.46 | 0.04 | KDLG1505-20 | 956.39 | 0.25 | 58.76 | 0.04 |
BLG1505-22 | 2451.73 | 0.88 | 10.12 | 0.03 | KDLG1505-21 | 2239.38 | 0.11 | 1.00 | 0.10 |
BLG1505-23 | 4735.18 | 0.49 | 6.95 | 0.01 | KDLG1505-22 | 1237.64 | 0.40 | 78.44 | 0.08 |
BLG1505-25 | 7874.87 | 0.38 | 75.37 | 0.03 | KDLG1505-23 | 984.18 | 0.19 | 2.61 | 0.04 |
BLG1505-28 | 1536.70 | 0.23 | 19.74 | 0.09 | KDLG1505-24 | 1358.25 | 0.39 | 4.30 | 0.16 |
BLG1505-29 | 2272.13 | 0.08 | 5.10 | 0.01 | KDLG1505-25 | 2239.38 | 0.11 | 1.00 | 0.10 |
BLG1505-32 | 3145.49 | 0.58 | 6.29 | 0.06 | KDLG1505-26 | 1436.78 | 0.46 | 22.59 | 0.07 |
BLG1505-33 | 3498.16 | 0.19 | 14.17 | 0.04 | KDLG1505-27 | 927.26 | 0.32 | 1.64 | 0.20 |
BLG1505-34 | 2030.05 | 0.20 | 17.03 | 0.02 | KDLG1505-28 | 1547.05 | 0.40 | 78.44 | 0.08 |
BLG1505-35 | 3027.49 | 0.11 | 1.72 | 0.04 | KDLG1505-29 | 12019.09 | 8.48 | 0.76 | 0.10 |
BLG1505-36 | 839.41 | 0.60 | 11.94 | 0.03 | KDLG1505-30 | 14048.07 | 4.49 | 0.60 | 0.01 |
BLG1505-39 | 580.31 | 0.23 | 40.26 | 0.07 | KDLG1505-31 | 1225.84 | 0.17 | 43.46 | 0.01 |
BLG1505-40 | 1876.54 | 0.10 | 1.51 | 0.07 | KDLG1505-32 | 1182.91 | 0.17 | 1.36 | 0.14 |
BLG1505-41 | 2089.35 | 0.15 | 1.48 | 0.06 | KDLG1505-33 | 914.13 | 0.23 | 56.28 | 0.04 |
BLG1505-42 | 1063.46 | 0.41 | 109.51 | 0.02 | KDLG1505-34 | 1086.01 | 0.20 | 2.90 | 0.05 |
BLG1505-43 | 1908.81 | 0.13 | 33.69 | 0.03 | KDLG1505-35 | 2110.92 | 0.28 | 4.97 | 0.05 |
BLG1505-44 | 2143.49 | 0.47 | 3.70 | 0.03 | KDLG1505-36 | 2632.39 | 0.11 | 2.53 | 0.09 |
BLG1505-45 | 1678.47 | 0.15 | 4.02 | 0.03 | KDLG1505-40 | 1243.55 | 0.37 | 14.64 | 0.06 |
BLG1505-47 | 2685.93 | 0.31 | 242.71 | 0.03 | KDLG1505-41 | 957.66 | 0.23 | 56.28 | 0.04 |
BLG1505-48 | 672.32 | 0.20 | 84.41 | 0.06 | KDLG1505-42 | 1086.07 | 0.13 | 7.95 | 0.03 |
BLG1505-50 | 1268.37 | 0.80 | 50.15 | 0.10 | KDLG1505-43 | 1200.39 | 0.13 | 7.95 | 0.03 |
BLG1505-51 | 5687.00 | 0.29 | 4.16 | 0.03 | KDLG1505-44 | 1301.33 | 0.17 | 43.46 | 0.02 |
BLG1505-52 | 1647.42 | 0.51 | 1.83 | 0.08 | KDLG1505-45 | 2261.70 | 0.28 | 4.97 | 0.05 |
BLG1505-53 | 2787.27 | 0.67 | 8.64 | 0.08 | KDLG1505-46 | 2046.30 | 0.28 | 4.97 | 0.05 |
BLG1505-54 | 4354.37 | 0.58 | 1.04 | 0.80 | KDLG1505-47 | 966.36 | 0.23 | 56.28 | 0.04 |
BLG1505-55 | 3269.21 | 0.62 | 1.14 | 0.43 | KDLG1505-49 | 1332.37 | 0.39 | 4.30 | 0.16 |
BLG1505-56 | 3138.72 | 0.23 | 7.90 | 0.03 | KDLG1505-50 | 1245.17 | 0.17 | 1.36 | 0.14 |
BLG1505-57 | 870.63 | 0.81 | 38.01 | 0.04 | KDLG1505-51 | 1034.29 | 0.20 | 2.90 | 0.05 |
BLG1505-58 | 1916.87 | 0.57 | 22.75 | 0.03 | KDLG1505-52 | 1346.12 | 0.17 | 20.68 | 0.04 |
BLG1505-60 | 1606.86 | 0.28 | 3.85 | 0.05 | KDLG1505-53 | 1637.92 | 0.36 | 3.68 | 0.13 |
BLG1505-61 | 1332.75 | 0.37 | 36.83 | 0.03 | KDLG1505-55 | 1221.72 | 0.32 | 2.86 | 0.24 |
BLG1505-62 | 1985.51 | 0.63 | 2.80 | 0.03 | KDLG1505-56 | 784.81 | 0.20 | 53.91 | 0.03 |
BLG1505-63 | 1788.09 | 0.47 | 50.54 | 0.02 | KDLG1505-58 | 1508.14 | 0.44 | 11.42 | 0.06 |
BLG1505-64 | 2791.14 | 0.26 | 1.21 | 0.06 | KDLG1505-59 | 1440.29 | 0.13 | 5.60 | 0.04 |
BLG1505-65 | 1131.07 | 0.07 | 1.11 | 0.22 | KDLG1505-60 | 1456.91 | 0.22 | 98.12 | 0.03 |
BLG1505-66 | 1240.06 | 0.15 | 33.60 | 0.03 | KDLG1505-61 | 1648.08 | 0.03 | 23.06 | 0.01 |
BLG1505-67 | 2157.51 | 0.38 | 11.21 | 0.02 | KDLG1505-62 | 668.87 | 0.27 | 26.48 | 0.04 |
BLG1505-68 | 1624.76 | 0.20 | 21.89 | 0.04 | KDLG1505-64 | 1130.44 | 0.12 | 128.36 | 0.06 |
BLG1505-69 | 1825.65 | 0.26 | 5.89 | 0.08 | KDLG1505-65 | 2027.76 | 0.32 | 3.71 | 0.09 |
BLG1505-70 | 1275.80 | 0.02 | 36.87 | 0.03 | KDLG1505-67 | 842.27 | 0.32 | 1.28 | 0.42 |
BLG1505-71 | 991.14 | 0.44 | 9.89 | 0.03 | KDLG1505-68 | 2606.20 | 0.03 | 20.30 | 0.01 |
BLG1505-72 | 1867.45 | 0.12 | 1.52 | 0.09 | KDLG1505-69 | 1109.86 | 0.33 | 36.85 | 0.06 |
BLG1505-73 | 1629.06 | 0.19 | 26.61 | 0.04 | KDLG1505-70 | 1365.42 | 0.48 | 183.22 | 0.09 |
BLG1505-74 | 832.37 | 0.62 | 104.84 | 0.04 | KDLG1505-71 | 628.30 | 0.29 | 1.75 | 0.09 |
BLG1505-75 | 1125.07 | 0.45 | 101.16 | 0.05 | KDLG1505-72 | 2280.25 | 0.21 | 26.12 | 0.03 |
BLG1505-76 | 2615.70 | 0.46 | 53.32 | 0.02 | KDLG1505-74 | 1657.44 | 0.15 | 9.50 | 0.04 |
BLG1505-77 | 2792.51 | 0.39 | 87.72 | 0.05 | KDLG1505-75 | 846.18 | 0.13 | 55.96 | 0.03 |
BLG1505-78 | 1583.42 | 0.07 | 141.86 | 0.03 | KDLG1505-76 | 3222.01 | 0.11 | 1.01 | 0.12 |
BLG1505-79 | 1942.86 | 0.36 | 77.16 | 0.14 | KDLG1505-77 | 1282.74 | 0.10 | 23.30 | 0.02 |
BLG1505-80 | 1452.64 | 0.60 | 1.89 | 0.34 | KDLG1505-78 | 1729.99 | 0.42 | 9.52 | 0.02 |
KDLG1505-79 | 2018.77 | 0.11 | 9.96 | 0.01 | |||||
KDLG1505-80 | 956.39 | 0.25 | 58.76 | 0.04 |

U-Pb Concordia diagrams and age histograms of the detrital zircons from the Zhongwunongshan Group sandstone samples (BLG1505 and KDLG1505)
The detrital zircons, in sample KDLG1505, are sub-angular to sub-rounded shapes with length/width ratios of 2:1–1:1. Except for the No. 29 and No. 30 analytical points, the majority of zircons shows well-developed oscillatory zoning or plate internal structure (Figure 3), with Th/U ratios greater than 0.1 (0.26–2.42). Besides, these zircons have similar REE concentration features with sample BLG1505, indicating the magmatic origin [44] (Table 1). Sixty-nine concordant zircon U-Pb ages of 2688–420 Ma were obtained from 69 zircon grains (Table 2, Figure 4c). These concordant ages are mainly grouped into two distinct age populations of 460–434 Ma and 966–726 Ma, defining dominant peaks at 456 Ma with 21 data, and secondary peaks of 828 Ma, 730 Ma and 956 Ma with 24 data (Figure 4d). About one-third of the grains are older than 1500 Ma with peaks at 2540 Ma and 1799 Ma.
LA-ICP-MS U-Pb analyses of zircons from the Zhongwunongshan Group sandstones
Sample Spot | ωB/ppm | Th/U | Isotropic ration | Apparent age (Ma) | |||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Th | U | 207Pb/206Pb | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | 207Pb/206Pb | 1σ | 207Pb/235U | 1σ | 206Pb/238U | 1σ | ||
Sample BLG1505 | |||||||||||||||
BLG1505-1 | 268 | 223 | 1.2 | 0.1522 | 0.0033 | 8.0457 | 0.1883 | 0.3829 | 0.0047 | 2372 | 31 | 2236 | 21 | 2090 | 22 |
BLG1505-2 | 78 | 69 | 1.13 | 0.0714 | 0.0057 | 1.3228 | 0.0939 | 0.1374 | 0.0031 | 970 | 163 | 856 | 41 | 830 | 18 |
BLG1505-3 | 253 | 388 | 0.65 | 0.0676 | 0.002 | 1.2823 | 0.0392 | 0.1378 | 0.0017 | 857 | 63 | 838 | 17 | 832 | 9 |
BLG1505-4 | 245 | 414 | 0.59 | 0.066 | 0.002 | 1.2356 | 0.037 | 0.1359 | 0.0017 | 807 | 68 | 817 | 17 | 822 | 9 |
BLG1505-6 | 28 | 41 | 0.68 | 0.0713 | 0.0049 | 1.3309 | 0.0913 | 0.1376 | 0.0029 | 969 | 141 | 859 | 40 | 831 | 16 |
BLG1505-7 | 159 | 348 | 0.46 | 0.0678 | 0.002 | 1.0042 | 0.0299 | 0.1076 | 0.0017 | 861 | 140 | 706 | 15 | 659 | 10 |
BLG1505-8 | 111 | 102 | 1.09 | 0.0751 | 0.0049 | 1.3863 | 0.0814 | 0.1358 | 0.0029 | 1072 | 99 | 883 | 35 | 821 | 16 |
BLG1505-9 | 261 | 418 | 0.62 | 0.0658 | 0.0053 | 0.9304 | 0.0708 | 0.1034 | 0.0026 | 1200 | 164 | 668 | 37 | 634 | 15 |
BLG1505-10 | 83 | 110 | 0.75 | 0.0745 | 0.0036 | 1.4032 | 0.0647 | 0.1378 | 0.0018 | 1054 | 98 | 890 | 27 | 832 | 10 |
BLG1505-11 | 65 | 111 | 0.58 | 0.0649 | 0.0024 | 1.2199 | 0.0493 | 0.1366 | 0.0026 | 769 | 78 | 810 | 23 | 826 | 15 |
BLG1505-12 | 423 | 354 | 1.2 | 0.0667 | 0.0017 | 1.2643 | 0.0353 | 0.1374 | 0.0021 | 829 | 52 | 830 | 16 | 830 | 12 |
BLG1505-14 | 45 | 56 | 0.8 | 0.0692 | 0.0039 | 1.1009 | 0.0592 | 0.119 | 0.003 | 906 | 117 | 754 | 29 | 725 | 17 |
BLG1505-15 | 342 | 548 | 0.62 | 0.0659 | 0.0019 | 1.253 | 0.0372 | 0.1377 | 0.0018 | 806 | 61 | 825 | 17 | 832 | 10 |
BLG1505-16 | 336 | 255 | 1.32 | 0.0673 | 0.0025 | 1.2903 | 0.0524 | 0.1381 | 0.0022 | 856 | 77 | 841 | 23 | 834 | 12 |
BLG1505-17 | 390 | 373 | 1.05 | 0.1576 | 0.0026 | 9.4864 | 0.1874 | 0.4342 | 0.0055 | 2431 | 28 | 2386 | 18 | 2325 | 24 |
BLG1505-18 | 965 | 742 | 1.3 | 0.0654 | 0.0014 | 1.2533 | 0.0296 | 0.1381 | 0.0018 | 787 | 44 | 825 | 13 | 834 | 10 |
BLG1505-19 | 110 | 111 | 0.99 | 0.0663 | 0.0027 | 1.2711 | 0.0557 | 0.138 | 0.0021 | 815 | 85 | 833 | 25 | 833 | 12 |
BLG1505-20 | 150 | 172 | 0.87 | 0.1586 | 0.0032 | 9.6778 | 0.222 | 0.4395 | 0.0059 | 2440 | 35 | 2405 | 21 | 2348 | 26 |
BLG1505-22 | 340 | 500 | 0.68 | 0.0641 | 0.002 | 1.0949 | 0.0374 | 0.1232 | 0.0022 | 743 | 67 | 751 | 18 | 749 | 12 |
BLG1505-23 | 381 | 1440 | 0.26 | 0.0978 | 0.0018 | 3.7797 | 0.0783 | 0.2782 | 0.0035 | 1583 | 33 | 1588 | 17 | 1582 | 18 |
BLG1505-25 | 854 | 933 | 0.92 | 0.0679 | 0.0013 | 1.2997 | 0.0292 | 0.1377 | 0.0016 | 878 | 38 | 846 | 13 | 831 | 9 |
BLG1505-28 | 1938 | 1367 | 1.42 | 0.0675 | 0.0014 | 1.2793 | 0.0311 | 0.1366 | 0.0018 | 854 | 43 | 837 | 14 | 825 | 10 |
BLG1505-29 | 113 | 334 | 0.34 | 0.0681 | 0.0021 | 1.2887 | 0.0413 | 0.1368 | 0.002 | 872 | 95 | 841 | 18 | 827 | 11 |
BLG1505-32 | 753 | 718 | 1.05 | 0.0701 | 0.0017 | 1.3323 | 0.0346 | 0.1375 | 0.0016 | 931 | 53 | 860 | 15 | 831 | 9 |
BLG1505-33 | 419 | 372 | 1.13 | 0.0694 | 0.0018 | 1.3259 | 0.0372 | 0.1383 | 0.0016 | 909 | 54 | 857 | 16 | 835 | 9 |
BLG1505-34 | 297 | 505 | 0.59 | 0.0683 | 0.0015 | 1.3012 | 0.033 | 0.1376 | 0.0017 | 880 | 46 | 846 | 15 | 831 | 10 |
BLG1505-35 | 92 | 222 | 0.42 | 0.0709 | 0.0023 | 1.3504 | 0.0455 | 0.1378 | 0.0019 | 967 | 67 | 868 | 20 | 832 | 10 |
BLG1505-36 | 26 | 65 | 0.41 | 0.0716 | 0.0032 | 1.3391 | 0.0603 | 0.1373 | 0.0025 | 976 | 91 | 863 | 26 | 829 | 14 |
BLG1505-39 | 301 | 293 | 1.03 | 0.0681 | 0.0018 | 1.2997 | 0.0398 | 0.1377 | 0.002 | 872 | 54 | 846 | 18 | 832 | 11 |
BLG1505-40 | 135 | 138 | 0.98 | 0.0706 | 0.0025 | 1.3408 | 0.0495 | 0.1378 | 0.0018 | 946 | 72 | 864 | 21 | 832 | 10 |
BLG1505-41 | 142 | 126 | 1.13 | 0.069 | 0.0025 | 1.311 | 0.0491 | 0.1379 | 0.0022 | 898 | 68 | 851 | 22 | 833 | 12 |
BLG1505-42 | 75 | 141 | 0.53 | 0.065 | 0.0025 | 1.2316 | 0.0498 | 0.1372 | 0.0021 | 772 | 75 | 815 | 23 | 829 | 12 |
BLG1505-43 | 248 | 342 | 0.72 | 0.0652 | 0.0017 | 1.1359 | 0.0301 | 0.126 | 0.0014 | 783 | 54 | 771 | 14 | 765 | 8 |
BLG1505-44 | 397 | 761 | 0.52 | 0.0663 | 0.0013 | 1.267 | 0.0296 | 0.1378 | 0.0016 | 817 | 41 | 831 | 13 | 832 | 9 |
BLG1505-45 | 186 | 270 | 0.69 | 0.0641 | 0.002 | 1.2264 | 0.0421 | 0.1382 | 0.0019 | 746 | 67 | 813 | 19 | 835 | 11 |
BLG1505-47 | 228 | 245 | 0.93 | 0.0667 | 0.0021 | 1.2674 | 0.0437 | 0.137 | 0.0019 | 828 | 67 | 831 | 20 | 828 | 11 |
BLG1505-48 | 266 | 220 | 1.21 | 0.0651 | 0.0021 | 1.243 | 0.0454 | 0.1373 | 0.0017 | 776 | 69 | 820 | 21 | 830 | 10 |
BLG1505-50 | 39 | 59 | 0.67 | 0.1302 | 0.0039 | 6.6389 | 0.2058 | 0.3685 | 0.0049 | 2102 | 52 | 2065 | 27 | 2022 | 23 |
BLG1505-51 | 256 | 335 | 0.76 | 0.074 | 0.0034 | 1.5303 | 0.0685 | 0.1522 | 0.0037 | 1040 | 94 | 943 | 27 | 913 | 21 |
BLG1505-52 | 467 | 658 | 0.71 | 0.0702 | 0.002 | 1.1767 | 0.0341 | 0.1216 | 0.0022 | 1000 | 58 | 790 | 16 | 740 | 13 |
BLG1505-53 | 739 | 1310 | 0.56 | 0.1535 | 0.0033 | 6.3792 | 0.1957 | 0.2972 | 0.0057 | 2385 | 37 | 2029 | 27 | 1677 | 28 |
BLG1505-54 | 1456 | 2260 | 0.64 | 0.0693 | 0.0016 | 1.0682 | 0.0346 | 0.1104 | 0.0023 | 906 | 48 | 738 | 17 | 675 | 14 |
BLG1505-55 | 441 | 511 | 0.86 | 0.0668 | 0.002 | 1.2313 | 0.0367 | 0.1328 | 0.0015 | 831 | 63 | 815 | 17 | 804 | 8 |
BLG1505-56 | 195 | 298 | 0.65 | 0.0642 | 0.0024 | 1.1864 | 0.044 | 0.1333 | 0.0018 | 746 | 50 | 794 | 20 | 807 | a |
BLG1505-57 | 205 | 654 | 0.31 | 0.1517 | 0.0032 | 7.701 | 0.1715 | 0.3657 | 0.0044 | 2365 | 236 | 2197 | 20 | 2009 | 21 |
BLG1505-58 | 63 | 115 | 0.55 | 0.0716 | 0.0044 | 1.2472 | 0.0715 | 0.1278 | 0.0021 | 976 | 121 | 822 | 32 | 775 | 12 |
BLG1505-60 | 191 | 273 | 0.7 | 0.066 | 0.0026 | 1.2226 | 0.0469 | 0.1335 | 0.0018 | 809 | 81 | 811 | 21 | 808 | 10 |
BLG1505-61 | 41 | 51 | 0.8 | 0.0844 | 0.0075 | 1.4496 | 0.1081 | 0.1337 | 0.0034 | 1302 | 172 | 910 | 45 | 809 | 20 |
BLG1505-62 | 70 | 91 | 0.76 | 0.0709 | 0.0044 | 1.5008 | 0.0886 | 0.1544 | 0.003 | 955 | 122 | 931 | 36 | 925 | 17 |
BLG1505-63 | 46 | 64 | 0.72 | 0.0735 | 0.0056 | 1.3289 | 0.0997 | 0.133 | 0.0033 | 1028 | 154 | 858 | 44 | 805 | 19 |
BLG1505-64 | 32 | 41 | 0.78 | 0.1035 | 0.0056 | 3.4637 | 0.1882 | 0.2449 | 0.0048 | 1687 | 99 | 1519 | 43 | 1412 | 25 |
BLG1505-65 | 50 | 73 | 0.7 | 0.1008 | 0.0035 | 3.9226 | 0.1352 | 0.2822 | 0.004 | 1639 | 64 | 1618 | 28 | 1603 | 20 |
BLG1505-66 | 60 | 82 | 0.74 | 0.0681 | 0.0045 | 1.2229 | 0.0755 | 0.1334 | 0.0027 | 872 | 139 | 811 | 34 | 807 | 15 |
BLG1505-67 | 141 | 209 | 0.68 | 0.0679 | 0.0038 | 1.2329 | 0.0602 | 0.1335 | 0.0022 | 865 | 117 | 816 | 27 | 808 | 13 |
BLG1505-68 | 64 | 118 | 0.54 | 0.0797 | 0.0045 | 1.4206 | 0.084 | 0.1304 | 0.0025 | 1191 | 113 | 898 | 35 | 790 | 14 |
BLG1505-69 | 328 | 406 | 0.81 | 0.0649 | 0.0018 | 1.1866 | 0.0345 | 0.1322 | 0.0019 | 770 | 53 | 794 | 16 | 801 | 11 |
BLG1505-70 | 297 | 627 | 0.47 | 0.1142 | 0.0015 | 4.7994 | 0.0715 | 0.3037 | 0.0028 | 1866 | 29 | 1785 | 13 | 1710 | 14 |
BLG1505-71 | 76 | 143 | 0.53 | 0.065 | 0.0039 | 1.1151 | 0.0621 | 0.1261 | 0.002 | 776 | 121 | 761 | 30 | 766 | 12 |
BLG1505-72 | 162 | 172 | 0.94 | 0.0645 | 0.0034 | 1.1186 | 0.0602 | 0.1248 | 0.0019 | 767 | 105 | 762 | 29 | 758 | 11 |
BLG1505-73 | 428 | 487 | 0.88 | 0.0673 | 0.002 | 1.242 | 0.0402 | 0.1337 | 0.0017 | 856 | 64 | 820 | 18 | 809 | 10 |
BLG1505-74 | 81 | 124 | 0.65 | 0.0647 | 0.0026 | 1.1824 | 0.0468 | 0.1331 | 0.0022 | 765 | 87 | 792 | 22 | 805 | 13 |
BLG1505-75 | 92 | 225 | 0.41 | 0.159 | 0.0033 | 9.9756 | 0.2137 | 0.4545 | 0.0057 | 2456 | 35 | 2433 | 20 | 2415 | 25 |
BLG1505-76 | 111 | 130 | 0.86 | 0.0671 | 0.0037 | 1.2004 | 0.0635 | 0.1313 | 0.0024 | 843 | 117 | 801 | 29 | 795 | 14 |
BLG1505-77 | 740 | 582 | 1.27 | 0.0642 | 0.0019 | 1.1833 | 0.0352 | 0.1334 | 0.0016 | 748 | 62 | 793 | 16 | 807 | 9 |
BLG1505-78 | 119 | 192 | 0.62 | 0.0679 | 0.0052 | 1.1445 | 0.0872 | 0.1231 | 0.0023 | 865 | 160 | 775 | 41 | 748 | 13 |
BLG1505-79 | 42 | 70 | 0.61 | 0.0816 | 0.005 | 1.7359 | 0.1124 | 0.1536 | 0.0027 | 1236 | 122 | 1022 | 42 | 921 | 15 |
BLG1505-80 | 758 | 652 | 1.16 | 0.0689 | 0.0021 | 1.2704 | 0.0385 | 0.1333 | 0.0016 | 895 | 68 | 833 | 17 | 807 | 9 |
Sample KDLG1505 | |||||||||||||||
KDLG1505-01 | 790 | 878 | 0.9 | 0.0586 | 0.001 | 0.727 | 0.0138 | 0.09 | 0.0009 | 552 | 36 | 555 | 11 | 555 | 6 |
KDLG1505-02 | 41 | 68 | 0.6 | 0.177 | 0.0035 | 12.2597 | 0.2563 | 0.5023 | 0.0052 | 2625 | 32 | 2624 | 55 | 2624 | 27 |
KDLG1505-03 | 541 | 526 | 1.03 | 0.0561 | 0.0014 | 0.5541 | 0.015 | 0.0716 | 0.0008 | 458 | 57 | 448 | 12 | 446 | 5 |
KDLG1505-04 | 386 | 345 | 1.12 | 0.0558 | 0.0022 | 0.5469 | 0.0221 | 0.071 | 0.0008 | 446 | 87 | 443 | 18 | 442 | 5 |
KDLG1505-06 | 324 | 299 | 1.08 | 0.0557 | 0.0026 | 0.5447 | 0.0258 | 0.0709 | 0.0008 | 440 | 105 | 442 | 21 | 442 | 5 |
KDLG1505-07 | 253 | 388 | 0.65 | 0.0676 | 0.002 | 1.2823 | 0.0392 | 0.1378 | 0.0017 | 857 | 63 | 838 | 17 | 832 | 9 |
KDLG1505-08 | 216 | 178 | 1.21 | 0.1838 | 0.0031 | 12.3995 | 0.2285 | 0.4892 | 0.0053 | 2688 | 28 | 2635 | 49 | 2567 | 28 |
KDLG1505-09 | 140 | 346 | 0.41 | 0.0651 | 0.0015 | 1.123 | 0.0266 | 0.1252 | 0.0013 | 776 | 47 | 764 | 18 | 760 | 8 |
KDLG1505-10 | 374 | 269 | 1.39 | 0.0559 | 0.0025 | 0.5444 | 0.0245 | 0.0706 | 0.0008 | 448 | 99 | 441 | 20 | 440 | 5 |
KDLG1505-11 | 111 | 277 | 0.4 | 0.064 | 0.0017 | 1.0624 | 0.029 | 0.1205 | 0.0013 | 741 | 57 | 735 | 20 | 733 | 8 |
KDLG1505-12 | 343 | 749 | 0.46 | 0.0709 | 0.0012 | 1.5623 | 0.028 | 0.1598 | 0.0017 | 955 | 34 | 955 | 17 | 956 | 10 |
KDLG1505-14 | 193 | 386 | 0.5 | 0.1583 | 0.0023 | 9.9527 | 0.159 | 0.4559 | 0.0049 | 2438 | 24 | 2430 | 39 | 2421 | 26 |
KDLG1505-15 | 85 | 123 | 0.69 | 0.1179 | 0.0019 | 5.6393 | 0.0982 | 0.347 | 0.0036 | 1924 | 29 | 1922 | 33 | 1920 | 20 |
KDLG1505-16 | 169 | 262 | 0.64 | 0.0978 | 0.0016 | 3.0352 | 0.054 | 0.2251 | 0.0023 | 1582 | 30 | 1417 | 25 | 1309 | 14 |
KDLG1505-17 | 89 | 277 | 0.32 | 0.0564 | 0.0021 | 0.5575 | 0.0216 | 0.0717 | 0.0008 | 469 | 83 | 450 | 17 | 446 | 5 |
KDLG1505-18 | 87 | 278 | 0.31 | 0.1695 | 0.0025 | 11.3624 | 0.1847 | 0.4861 | 0.0051 | 2553 | 24 | 2553 | 42 | 2554 | 27 |
KDLG1505-19 | 400 | 453 | 0.88 | 0.0563 | 0.0015 | 0.5457 | 0.0159 | 0.0703 | 0.0007 | 463 | 61 | 442 | 13 | 438 | 5 |
KDLG1505-20 | 146 | 215 | 0.68 | 0.1366 | 0.002 | 7.5941 | 0.1211 | 0.4032 | 0.0041 | 2184 | 26 | 2184 | 35 | 2184 | 22 |
KDLG1505-21 | 353 | 666 | 0.53 | 0.071 | 0.0011 | 1.5708 | 0.0257 | 0.1606 | 0.0016 | 956 | 31 | 959 | 16 | 960 | 10 |
KDLG1505-22 | 420 | 453 | 0.93 | 0.0558 | 0.0014 | 0.5462 | 0.0142 | 0.0711 | 0.0007 | 443 | 55 | 443 | 12 | 443 | 5 |
KDLG1505-23 | 272 | 409 | 0.66 | 0.0665 | 0.0012 | 1.2489 | 0.0235 | 0.1363 | 0.0014 | 821 | 36 | 823 | 15 | 824 | 9 |
KDLG1505-24 | 477 | 773 | 0.62 | 0.0561 | 0.0012 | 0.555 | 0.0125 | 0.0717 | 0.0008 | 458 | 48 | 448 | 10 | 446 | 5 |
KDLG1505-25 | 822 | 1014 | 0.81 | 0.0714 | 0.001 | 1.5729 | 0.024 | 0.1599 | 0.0017 | 968 | 27 | 960 | 15 | 956 | 10 |
KDLG1505-26 | 111 | 225 | 0.49 | 0.0566 | 0.0027 | 0.5569 | 0.0271 | 0.0714 | 0.0008 | 474 | 105 | 450 | 22 | 445 | 5 |
KDLG1505-27 | 136 | 220 | 0.62 | 0.0564 | 0.0027 | 0.552 | 0.0263 | 0.071 | 0.0008 | 467 | 104 | 446 | 21 | 442 | 5 |
KDLG1505-28 | 790 | 878 | 0.9 | 0.0586 | 0.001 | 0.727 | 0.0138 | 0.09 | 0.0009 | 552 | 36 | 555 | 11 | 555 | 6 |
KDLG1505-29 | 92 | 1054 | 0.09 | 0.0699 | 0.001 | 1.4749 | 0.0229 | 0.1531 | 0.0016 | 924 | 28 | 920 | 14 | 919 | 10 |
KDLG1505-30 | 136 | 898 | 0.15 | 0.1126 | 0.0015 | 4.2313 | 0.0659 | 0.2725 | 0.0029 | 1842 | 25 | 1680 | 26 | 1553 | 17 |
KDLG1505-31 | 302 | 481 | 0.63 | 0.0659 | 0.0012 | 1.175 | 0.0232 | 0.1294 | 0.0013 | 802 | 38 | 789 | 16 | 784 | 8 |
KDLG1505-32 | 107 | 304 | 0.35 | 0.056 | 0.0162 | 0.5377 | 0.1544 | 0.0696 | 0.0009 | 454 | 640 | 437 | 125 | 434 | 5 |
KDLG1505-33 | 102 | 195 | 0.52 | 0.1615 | 0.0024 | 8.4156 | 0.1353 | 0.3779 | 0.0038 | 2472 | 25 | 2277 | 37 | 2066 | 21 |
KDLG1505-34 | 965 | 742 | 1.3 | 0.0654 | 0.0014 | 1.2533 | 0.0296 | 0.1381 | 0.0018 | 787 | 44 | 825 | 13 | 834 | 10 |
KDLG1505-35 | 229 | 150 | 1.53 | 0.064 | 0.0024 | 1.0639 | 0.0403 | 0.1205 | 0.0013 | 743 | 80 | 736 | 28 | 733 | 8 |
KDLG1505-36 | 319 | 881 | 0.36 | 0.0797 | 0.0011 | 1.7772 | 0.0279 | 0.1616 | 0.0016 | 1191 | 28 | 1037 | 16 | 966 | 10 |
KDLG1505-40 | 656 | 648 | 1.01 | 0.0563 | 0.0013 | 0.5506 | 0.0129 | 0.0709 | 0.0007 | 465 | 50 | 445 | 10 | 442 | 5 |
KDLG1505-41 | 269 | 695 | 0.39 | 0.1742 | 0.0027 | 10.4835 | 0.1796 | 0.4364 | 0.0046 | 2599 | 26 | 2478 | 42 | 2335 | 25 |
KDLG1505-42 | 218 | 125 | 1.75 | 0.0679 | 0.0021 | 1.3418 | 0.0485 | 0.1432 | 0.0021 | 867 | 65 | 864 | 31 | 863 | 13 |
KDLG1505-43 | 41 | 51 | 0.8 | 0.0783 | 0.0068 | 1.57 | 0.1347 | 0.1457 | 0.0039 | 1155 | 173 | 958 | 53 | 877 | 22 |
KDLG1505-44 | 237 | 337 | 0.7 | 0.0657 | 0.0012 | 1.1946 | 0.0236 | 0.1319 | 0.0013 | 796 | 39 | 798 | 16 | 799 | 8 |
KDLG1505-45 | 1411 | 637 | 2.22 | 0.0645 | 0.0011 | 1.0997 | 0.0199 | 0.1236 | 0.0013 | 758 | 35 | 753 | 14 | 751 | 8 |
KDLG1505-46 | 332 | 154 | 2.15 | 0.0643 | 0.0025 | 1.0568 | 0.0422 | 0.1193 | 0.0013 | 750 | 82 | 732 | 29 | 726 | 8 |
KDLG1505-47 | 266 | 541 | 0.49 | 0.1707 | 0.0023 | 9.906 | 0.1598 | 0.4208 | 0.0047 | 2565 | 23 | 2426 | 39 | 2264 | 25 |
KDLG1505-49 | 267 | 391 | 0.68 | 0.0565 | 0.0016 | 0.5761 | 0.0171 | 0.0739 | 0.0008 | 474 | 64 | 462 | 14 | 460 | 5 |
KDLG1505-50 | 178 | 261 | 0.68 | 0.0561 | 0.0026 | 0.5451 | 0.0267 | 0.0705 | 0.0008 | 456 | 102 | 442 | 22 | 439 | 5 |
KDLG1505-51 | 429 | 339 | 1.27 | 0.0674 | 0.0014 | 1.2778 | 0.0288 | 0.1376 | 0.0014 | 849 | 42 | 836 | 19 | 831 | 9 |
KDLG1505-52 | 82 | 78 | 1.05 | 0.1376 | 0.0024 | 6.5832 | 0.1296 | 0.347 | 0.004 | 2197 | 30 | 2057 | 40 | 1920 | 22 |
KDLG1505-53 | 110 | 219 | 0.5 | 0.0588 | 0.0013 | 0.6957 | 0.0167 | 0.0857 | 0.001 | 561 | 48 | 536 | 13 | 530 | 6 |
KDLG1505-55 | 372 | 456 | 0.82 | 0.0556 | 0.0026 | 0.5483 | 0.026 | 0.0717 | 0.0012 | 435 | 136 | 444 | 17 | 447 | 7 |
KDLG1505-56 | 37 | 153 | 0.24 | 0.1521 | 0.0044 | 9.2775 | 0.3286 | 0.4395 | 0.0101 | 2369 | 49 | 2366 | 32 | 2348 | 45 |
KDLG1505-58 | 324 | 554 | 0.58 | 0.0554 | 0.0023 | 0.5455 | 0.0231 | 0.0714 | 0.0011 | 428 | 94 | 442 | 15 | 444 | 6 |
KDLG1505-59 | 99 | 143 | 0.7 | 0.0706 | 0.0038 | 1.353 | 0.0684 | 0.1398 | 0.0027 | 946 | 111 | 869 | 30 | 844 | 15 |
KDLG1505-60 | 65 | 106 | 0.62 | 0.0707 | 0.0043 | 1.2933 | 0.0811 | 0.1342 | 0.0031 | 950 | 125 | 843 | 36 | 812 | 18 |
KDLG1505-61 | 89 | 159 | 0.56 | 0.0618 | 0.0041 | 0.5957 | 0.0415 | 0.0701 | 0.0016 | 733 | 144 | 475 | 26 | 436 | 9 |
KDLG1505-62 | 32 | 76 | 0.43 | 0.1185 | 0.0045 | 5.7298 | 0.2059 | 0.3509 | 0.0061 | 1944 | 101 | 1936 | 31 | 1939 | 29 |
KDLG1505-64 | 65 | 124 | 0.52 | 0.1112 | 0.0038 | 5.1238 | 0.1714 | 0.3327 | 0.0061 | 1820 | 62 | 1840 | 28 | 1851 | 30 |
KDLG1505-65 | 141 | 145 | 0.98 | 0.065 | 0.0036 | 1.0661 | 0.0553 | 0.1196 | 0.0025 | 772 | 117 | 737 | 27 | 728 | 14 |
KDLG1505-67 | 172 | 219 | 0.79 | 0.0574 | 0.004 | 0.5676 | 0.04 | 0.0712 | 0.0014 | 506 | 152 | 456 | 26 | 443 | 9 |
KDLG1505-68 | 104 | 187 | 0.56 | 0.0524 | 0.004 | 0.4916 | 0.0371 | 0.0674 | 0.0014 | 306 | 179 | 406 | 25 | 420 | 9 |
KDLG1505-69 | 345 | 383 | 0.9 | 0.0555 | 0.0023 | 0.5542 | 0.0239 | 0.0713 | 0.0012 | 435 | 89 | 448 | 16 | 444 | 7 |
KDLG1505-70 | 402 | 407 | 0.99 | 0.0572 | 0.0028 | 0.5649 | 0.0259 | 0.0714 | 0.001 | 498 | 112 | 455 | 17 | 445 | 6 |
KDLG1505-71 | 142 | 264 | 0.54 | 0.0686 | 0.0026 | 1.2796 | 0.0475 | 0.1343 | 0.0019 | 887 | 79 | 837 | 21 | 812 | 11 |
KDLG1505-72 | 373 | 470 | 0.79 | 0.0653 | 0.0022 | 1.1107 | 0.0383 | 0.122 | 0.0016 | 783 | 72 | 758 | 18 | 742 | 9 |
KDLG1505-74 | 78 | 123 | 0.64 | 0.1232 | 0.0038 | 6.2775 | 0.196 | 0.3664 | 0.0058 | 2003 | 55 | 2015 | 27 | 2013 | 27 |
KDLG1505-75 | 71 | 195 | 0.36 | 0.0729 | 0.003 | 1.5292 | 0.0647 | 0.1507 | 0.0023 | 1013 | 83 | 942 | 26 | 905 | 13 |
KDLG1505-76 | 437 | 301 | 1.45 | 0.0753 | 0.0028 | 1.6259 | 0.0638 | 0.1554 | 0.0025 | 1076 | 69 | 980 | 25 | 931 | 14 |
KDLG1505-77 | 102 | 239 | 0.43 | 0.0707 | 0.0033 | 1.3061 | 0.0616 | 0.1332 | 0.0024 | 950 | 94 | 848 | 27 | 806 | 14 |
KDLG1505-78 | 30 | 41 | 0.73 | 0.1151 | 0.0054 | 5.2916 | 0.2536 | 0.3334 | 0.0064 | 1883 | 85 | 1868 | 41 | 1855 | 31 |
KDLG1505-79 | 75 | 141 | 0.53 | 0.0807 | 0.0027 | 2.0223 | 0.0668 | 0.1801 | 0.0022 | 1215 | 67 | 1123 | 22 | 1068 | 12 |
KDLG1505-80 | 88 | 185 | 0.48 | 0.1448 | 0.0036 | 7.6864 | 0.179 | 0.3822 | 0.0042 | 2287 | 43 | 2195 | 21 | 2087 | 20 |
4.2 Zircon Hf isotopic analysis
Zircon Lu-Hf isotopic analysis were carried out on samples KDLG1505 and BLG1505 with completed zircon U-Pb dating. The related results are listed in Table 3. For samples KDLG1505 and BLG1505, the detrital zircons of the Zhongwunongshan Group were found to be dominated by late Early Paleozoic and Neoproterozoic (Table 2, Figure 4). The Hf isotopic analysis results indicated that the vast majority of the zircons had negative ∈Hf(t) (Figure 5). Such ∈Hf(t) distribution characteristics confirmed that the detrital zircons of the Zhongwunongshan Group were mainly sourced from crustal recycling. However, some zircons with positive ∈Hf(t) in BLG1505 proved a depleted mantle source existed (Table 3, Figure 5). The zircons of the Zhongwunongshan Group in the eastern section of the study area had two major U-Pb age populations of 460–434 Ma and 966–726 Ma (Figure 4d). Also, the corresponding ∈Hf(t) were calculated at −9.6 to −3.1, and −15.9 to −0.8, respectively, with the exception of the No.21 point which had an ∈Hf(t) of 3.8 (Figure 5). The two-stage model ages (TcDM) were between 1621 Ma and 2029 Ma, and between 1581 Ma and 2815 Ma respectively. The averages were determined to be 1864 Ma and 2362 Ma, respectively (Table 3). In the western section of the study area, the zircons had a major U-Pb age population of 925–725 Ma (Figure 4d); vHf(t) between −11.9 and 9.5 (Figure 5); and average TcDM of 1692 Ma, which was lower than that of the Neoproterozoic zircons in the eastern section.
Hf isotopic compositions of zircons from the Zhongwunongshan Group sandstones
Sample | U-Pb Age (Ma) | 2σ | 2σ | ϵHf(0) ϵHf(t) | |||||
---|---|---|---|---|---|---|---|---|---|
Sample BLG1505 | |||||||||
BLG1505-01 | 2372 | 0.014893 | 0.000503 | 0.000008 | 0.281265 | 0.000023 | -53.3 | -0.95 | 2960 |
BLG1505-02 | 830 | 0.034457 | 0.001056 | 0.000039 | 0.282392 | 0.000027 | -13.43 | 4.34 | 1446 |
BLG1505-03 | 832 | 0.020833 | 0.000634 | 0.000002 | 0.28227 | 0.000022 | -17.75 | 0.27 | 1704 |
BLG1505-04 | 822 | 0.054682 | 0.001565 | 0.000026 | 0.2824 | 0.000022 | -13.16 | 4.16 | 1452 |
BLG1505-06 | 831 | 0.018978 | 0.000557 | 0.000003 | 0.28253 | 0.000025 | -8.57 | 9.5 | 1120 |
BLG1505-07 | 659 | 0.033059 | 0.001168 | 0.000058 | 0.282396 | 0.000023 | -13.29 | 0.74 | 1542 |
BLG1505-08 | 821 | 0.037872 | 0.00114 | 0.000028 | 0.282345 | 0.000024 | -15.11 | 2.4 | 1561 |
BLG1505-10 | 832 | 0.040049 | 0.001355 | 0.000015 | 0.282495 | 0.000022 | -9.79 | 7.86 | 1225 |
BLG1505-11 | 826 | 0.02147 | 0.000714 | 0.000007 | 0.282353 | 0.000023 | -14.8 | 3.05 | 1523 |
BLG1505-12 | 830 | 0.097608 | 0.003171 | 0.000059 | 0.282416 | 0.00002 | -12.58 | 4.02 | 1467 |
BLG1505-14 | 725 | 0.049159 | 0.001682 | 0.000156 | 0.282393 | 0.000028 | -13.41 | 1.79 | 1527 |
BLG1505-15 | 832 | 0.051351 | 0.001449 | 0.000066 | 0.28213 | 0.000027 | -22.72 | -5.15 | 2045 |
BLG1505-17 | 2431 | 0.02254 | 0.00073 | 0.000003 | 0.281209 | 0.000024 | -55.29 | -1.97 | 3068 |
BLG1505-18 | 834 | 0.077842 | 0.002077 | 0.000018 | 0.281954 | 0.000027 | -28.92 | -11.66 | 2455 |
BLG1505-19 | 833 | 0.022269 | 0.00071 | 0.000003 | 0.282398 | 0.000025 | -13.24 | 4.8 | 1421 |
BLG1505-20 | 2440 | 0.017897 | 0.000506 | 0.000002 | 0.280988 | 0.000019 | -63.1 | -9.27 | 3519 |
BLG1505-22 | 749 | 0.02431 | 0.000792 | 0.000016 | 0.282313 | 0.000025 | -16.22 | -0.09 | 1663 |
BLG1505-23 | 1583 | 0.062695 | 0.001971 | 0.000062 | 0.281681 | 0.000022 | -38.57 | -5.47 | 2634 |
BLG1505-25 | 831 | 0.100069 | 0.003164 | 0.00004 | 0.2825 | 0.000026 | -9.64 | 6.98 | 1280 |
BLG1505-28 | 825 | 0.018694 | 0.000616 | 0.000008 | 0.281991 | 0.000026 | -27.61 | -9.73 | 2327 |
BLG1505-29 | 827 | 0.019528 | 0.00055 | 0.000023 | 0.282137 | 0.000019 | -22.44 | -4.48 | 2000 |
BLG1505-32 | 831 | 0.036456 | 0.001106 | 0.000002 | 0.282304 | 0.000026 | -16.54 | 1.21 | 1644 |
BLG1505-33 | 835 | 0.040226 | 0.001201 | 0.000007 | 0.282356 | 0.000026 | -14.72 | 3.07 | 1530 |
BLG1505-34 | 831 | 0.026978 | 0.000853 | 0.00001 | 0.282167 | 0.000025 | -21.39 | -3.5 | 1941 |
BLG1505-35 | 832 | 0.049137 | 0.001592 | 0.00002 | 0.282503 | 0.000025 | -9.52 | 8 | 1217 |
BLG1505-36 | 829 | 0.014769 | 0.000522 | 0.000049 | 0.282239 | 0.000021 | -18.87 | -0.86 | 1773 |
BLG1505-39 | 832 | 0.008091 | 0.000247 | 0.000001 | 0.282022 | 0.000027 | -26.53 | -8.3 | 2242 |
BLG1505-40 | 832 | 0.038534 | 0.001343 | 0.000065 | 0.282252 | 0.000025 | -18.37 | -0.75 | 1768 |
BLG1505-41 | 833 | 0.039793 | 0.001258 | 0.000039 | 0.282269 | 0.000028 | -17.77 | -0.06 | 1727 |
BLG1505-42 | 829 | 0.030067 | 0.001048 | 0.000023 | 0.282508 | 0.000025 | -9.33 | 8.43 | 1187 |
BLG1505-43 | 765 | 0.032088 | 0.001025 | 0.000015 | 0.282177 | 0.000026 | -21.04 | -4.69 | 1965 |
BLG1505-44 | 832 | 0.060327 | 0.00168 | 0.000023 | 0.282253 | 0.000024 | -18.34 | -0.9 | 1777 |
BLG1505-45 | 835 | 0.025155 | 0.000839 | 0.000011 | 0.282158 | 0.000025 | -21.7 | -3.73 | 1959 |
BLG1505-47 | 828 | 0.046628 | 0.001702 | 0.000024 | 0.28241 | 0.000027 | -12.8 | 4.54 | 1430 |
BLG1505-48 | 830 | 0.009163 | 0.000271 | 0.000001 | 0.281923 | 0.000026 | -30.01 | -11.85 | 2463 |
BLG1505-50 | 2102 | 0.007978 | 0.000196 | 0.000003 | 0.281127 | 0.000023 | -58.16 | -11.48 | 3398 |
Sample KDLG1505 | |||||||||
KDLG1505-02 | 2625 | 0.010742 | 0.000327 | 0.00001 | 0.281012 | 0.000023 | -62.23 | -3.86 | 3331 |
KDLG1505-03 | 446 | 0.019216 | 0.000612 | 0.000009 | 0.282379 | 0.000021 | -13.88 | -4.26 | 1696 |
KDLG1505-04 | 442 | 0.019617 | 0.000607 | 0.000031 | 0.282333 | 0.000021 | -15.53 | -5.98 | 1802 |
KDLG1505-06 | 442 | 0.015493 | 0.000484 | 0.000015 | 0.282233 | 0.000026 | -19.08 | -9.48 | 2023 |
KDLG1505-07 | 832 | 0.013424 | 0.000359 | 0.000012 | 0.281942 | 0.000021 | -29.36 | -11.2 | 2424 |
KDLG1505-08 | 2688 | 0.047057 | 0.001472 | 0.000005 | 0.28101 | 0.000028 | -62.32 | -4.6 | 3425 |
KDLG1505-09 | 760 | 0.049388 | 0.001607 | 0.000047 | 0.281925 | 0.000027 | -29.95 | -14.01 | 2545 |
KDLG1505-10 | 440 | 0.017338 | 0.000533 | 0.000003 | 0.282231 | 0.000026 | -19.13 | -9.6 | 2029 |
KDLG1505-11 | 733 | 0.017129 | 0.000497 | 0.000012 | 0.282114 | 0.000022 | -23.28 | -7.35 | 2108 |
KDLG1505-12 | 956 | 0.018144 | 0.000532 | 0.000007 | 0.282162 | 0.000024 | -21.56 | -0.75 | 1864 |
KDLG1505-13 | 439 | 0.021354 | 0.000672 | 0.000009 | 0.282355 | 0.000021 | -14.74 | -5.27 | 1755 |
KDLG1505-14 | 2438 | 0.0212 | 0.000651 | 0.000022 | 0.281421 | 0.000024 | -47.76 | 5.87 | 2593 |
KDLG1505-15 | 1924 | 0.017898 | 0.00052 | 0.000014 | 0.281571 | 0.000025 | -42.48 | -0.2 | 2570 |
KDLG1505-16 | 1582 | 0.046345 | 0.001719 | 0.000076 | 0.281804 | 0.000028 | -34.23 | -0.84 | 2349 |
KDLG1505-17 | 446 | 0.040986 | 0.001226 | 0.000023 | 0.282275 | 0.000025 | -17.59 | -8.16 | 1941 |
KDLG1505-18 | 2553 | 0.017914 | 0.000595 | 0.000008 | 0.281258 | 0.000025 | -53.54 | 2.77 | 2871 |
KDLG1505-19 | 438 | 0.027397 | 0.000829 | 0.000025 | 0.282303 | 0.000022 | -16.58 | -7.16 | 1875 |
KDLG1505-20 | 2184 | 0.021474 | 0.000679 | 0.000034 | 0.281287 | 0.000025 | -52.53 | -4.7 | 3045 |
KDLG1505-21 | 960 | 0.057063 | 0.001823 | 0.000071 | 0.282312 | 0.000027 | -16.27 | 3.81 | 1581 |
KDLG1505-22 | 443 | 0.015489 | 0.000483 | 0.000006 | 0.282413 | 0.000024 | -12.71 | -3.09 | 1621 |
KDLG1505-23 | 824 | 0.05065 | 0.001531 | 0.000043 | 0.281915 | 0.00002 | -30.32 | -12.98 | 2529 |
KDLG1505-24 | 446 | 0.03988 | 0.001225 | 0.000039 | 0.282374 | 0.000026 | -14.08 | -4.62 | 1720 |
KDLG1505-25 | 956 | 0.053563 | 0.001465 | 0.000019 | 0.281839 | 0.000024 | -33 | -12.83 | 2617 |
KDLG1505-26 | 445 | 0.036234 | 0.001077 | 0.000012 | 0.282293 | 0.000022 | -16.95 | -7.47 | 1898 |
KDLG1505-27 | 442 | 0.01839 | 0.000546 | 0.000005 | 0.28231 | 0.000024 | -16.33 | -6.76 | 1853 |
KDLG1505-28 | 555 | 0.027264 | 0.000786 | 0.000013 | 0.282192 | 0.000027 | -20.52 | -8.58 | 2052 |
KDLG1505-30 | 1842 | 0.029848 | 0.00085 | 0.000005 | 0.28161 | 0.000023 | -41.08 | -1.04 | 2559 |
KDLG1505-31 | 784 | 0.058477 | 0.001719 | 0.000023 | 0.281977 | 0.00003 | -28.1 | -11.71 | 2419 |
KDLG1505-32 | 434 | 0.02181 | 0.000654 | 0.000013 | 0.282242 | 0.000021 | -18.73 | -9.38 | 2010 |
KDLG1505-33 | 2472 | 0.027235 | 0.000883 | 0.000008 | 0.280971 | 0.000025 | -63.68 | -9.74 | 3572 |
KDLG1505-34 | 834 | 0.043409 | 0.001189 | 0.000005 | 0.281869 | 0.000026 | -31.94 | -14.21 | 2612 |
KDLG1505-35 | 733 | 0.055346 | 0.001726 | 0.000011 | 0.282044 | 0.000028 | -25.75 | -10.43 | 2300 |
KDLG1505-36 | 966 | 0.011427 | 0.00034 | 0.000006 | 0.281726 | 0.000023 | -37 | -15.87 | 2815 |
KDLG1505-40 | 442 | 0.019077 | 0.000597 | 0.000011 | 0.282325 | 0.000021 | -15.82 | -6.26 | 1820 |
KDLG1505-42 | 877 | 0.049528 | 0.001589 | 0.000013 | 0.282037 | 0.00003 | -25.98 | -7.54 | 2228 |
KDLG1505-43 | 1152 | 0.01379 | 0.000446 | 0.000007 | 0.28186 | 0.000021 | -32.26 | -7.1 | 2409 |
KDLG1505-44 | 799 | 0.045299 | 0.001299 | 0.000012 | 0.281855 | 0.000025 | -32.44 | -15.52 | 2667 |
KDLG1505-45 | 751 | 0.080713 | 0.002377 | 0.000026 | 0.281896 | 0.00003 | -30.97 | -15.59 | 2637 |
KDLG1505-46 | 726 | 0.087725 | 0.00254 | 0.000021 | 0.281989 | 0.00003 | -27.69 | -12.93 | 2450 |
KDLG1505-47 | 2565 | 0.047276 | 0.001282 | 0.000049 | 0.28114 | 0.000023 | -57.73 | -2.36 | 3195 |
KDLG1505-49 | 460 | 0.018305 | 0.000567 | 0.000021 | 0.282323 | 0.000021 | -15.88 | -5.93 | 1813 |
KDLG1505-50 | 439 | 0.044257 | 0.001376 | 0.000035 | 0.282259 | 0.000029 | -18.15 | -8.91 | 1983 |
KDLG1505-51 | 831 | 0.029402 | 0.000888 | 0.00001 | 0.282014 | 0.00003 | -26.81 | -8.96 | 2282 |
KDLG1505-52 | 2197 | 0.015031 | 0.000448 | 0.000003 | 0.281306 | 0.000025 | -51.84 | -3.34 | 2972 |
KDLG1505-53 | 530 | 0.030277 | 0.000878 | 0.000002 | 0.282029 | 0.00003 | -26.28 | -14.94 | 2432 |

Plot of zircon Hf isotopes vs. crystallization age from the Zhongwunongshan Group sandstones
5 Discussion
5.1 Sources of detritus
The zircon U-Pb age histogram of the clastic samples showed two major populations (460–434 Ma and 966–725 Ma), which illustrated that the zircons of the Zhongwunongshan Group were mainly derived from Neoproterozoic and late Early Palaeozoic detritus source rocks (Figure 4). The Neoproterozoic granitic gneiss with similar formation ages was found in the Yuqia-Shaliuhe HP-UHP metamorphic belt, located on the southern margin of the NQSB [3, 27]. Due to the continental collision between the Olongbruk Microblock and the Qaidam Block, the most important Neoproterozoic tonalite-monzonitic granites were formed, and intruded into the Yuqia-Shaliuhe HP-UHP metamorphic belt during the Jinningian period (1000–800 Ma) [28, 29, 36, 45]. In addition, the Hf isotopic results showed that the Neoproterozoic zircons from the sample KDLG1505 also had similar model age (2815–1581 Ma, with a peak of 2362 Ma), and a similar origin (dominated by ancient crust melting) as the Neoproterozoic Shaliuhe granitic gneiss in the eastern section of the Yuqia-Shaliuhe HP-UHP metamorphic belt [2, 46]. However, since the two-stage model age (TcDM) of sample BLG1505 in the western section was lower than that in the eastern section, the ∈Hf(t) was found to be significantly higher (Table 2, Figure 5). These results indicated that the Neoproterozoic detritus source rock in the western section may have been mixed with depleted mantle. A previous survey revealed that eclogite which developed in the Xitieshan granitic gneiss of the western section was originally the oceanic ridge basalt, with crystallization ages of 1000–800 Ma and positive ∈Nd (t) [47, 48]. It confirmed that the Neoproterozoic granite gneiss in the west may have been formed during a crust-remelting process, and mixed with depleted mantle, which caused the model age TCDM to be below the normal value in the east [49, 50]. Therefore, in the Yuqia-Shaliuhe HP-UHP metamorphic belt of North Qaidam, the Neoproterozoic granitic gneiss can likely be one of the major detritus source for the Zhongwunongshan Group.
The detrital zircon U-Pb age histogram also showed that the late Early Paleozoic detritus source rocks within the age population of 460–434 Ma were another major source of the Zhongwunongshan Group (Figure 4). However, the zircons in this age range only appeared in the eastern section of the study area. It was indicated that the detritus source rocks were slightly different between the eastern and western sections of the study area. The Hf isotopic analysis showed that the late Paleozoic detritus source rocks were mainly derived from the remelted magma of the lower crust reservoir (Figure 5). A previous survey indicated the sustained oceanic crust subduction occurred when the Qaidam block northward dived beneath the Olongbruk Microblock during the Late Ordovician [36, 63]. Due to the rapid subduction, the thickened lower continental crust melting took place which formed the active epicontinental arc tonalite-granodiorite (450–440 Ma) in the Tanjianshan ophiolite-volcanic arc belt [3, 12, 28, 51]. As the only Early Paleozoic continental arc granites within the age population in the study area, the Tomorit quartz diorite–monzogranite series approaching to the south of Ulan was another source for the Zhongwunongshan Group.
5.2 Age of the Zhongwunongshan Group
Because the deposition age of sedimentary formation must be younger than the youngest detrital zircon, which can be regarded as the maximum deposition age for this formation [52, 53, 54]. This approach has been successfully applied to the time determination for sedimentary strata, especially to successions where biostratigraphy cannot be used [55, 56].
In this study, the 206Pb/238U age of the youngest detrital zircon (KDLG1505-32) of the Zhongwunongshan Group is 434±5 Ma (Table 2), and can be regarded as the maximum deposition age of the Zhongwunongshan Group. As the major provenances for the Zhongwunongshan Group, the significant input of detritus materials derived from the Yuqia-Shaliuhe HP-UHP metamorphic belt and the Tanjianshan ophiolite-volcanic arc belt to the south (Figure 1b). The widespread Maonianshan Group in Devonian period of the above source regions was characterized of the youngest detrital zircon age of 407.9 Ma [57], which limited the deposition of the Maoniushan Group to be later than the Early Devonian. However, the detrital zircon U-Pb ages of the Zhongwunongshan Group were all older than 407.9 Ma, which indicated the absence of detritus materials of 407.9 Ma in the source regions during the Zhongwunongshan group deposited, and limited the depositional age of that strata to be older than early Devonian (407.9 Ma).
5.3 Tectonic significance
In the period from late Late Neoproterozoic to Middle Ordovician (580–465 Ma), the North Qaidam oceanic crust subducted northward beneath the Olongbruk Microblock, resulted in the formation of the Tanjianshan volcanic island arc [32, 58, 59] and Yuqia-Shaliuhe ultrahigh pressure metamorphic rocks [60, 61]. This subduction also induced compensatory convection of the mantle wedge behind the island arc, and forced deep-seatedmagmatoupwellwhich resulted in back-arc extension [63].
During the Late Ordovician to Middle Silurian (465–435 Ma), the North Qaidam Ocean closed and the Qaidam Block collided with the Olongbruk Microblock. Due to the rapid subdution, the thickened lower continental crust melting took place which formed the epicontinental arc tonalites-granodiorites (450–440 Ma) in the Tanjianshan ophiolite-volcanic arc belt [3, 12, 28]. At the same time, the back-arc basin to the north of the North Qaidam deposited thick flysch sediments in the ZWSB and the adjacent South Qilian area during the Silurian [63].
The Late Silurian-Early Devonian (435–400 Ma) is an important transition period for the Early Paleozoic tectonic evolution in the North Qaidam. The continuous movement of the asthenosphere with respect to the lithosphere at this stage promoted detachment within the lithosphere and caused partial melting of the sub-ducted continental crust. Meanwhile the alkaline basaltic magma, derived from remelting of deep subduction of the oceanic crust, uplifted and mixed with the continental crust magma. The mixed magma was finally emplaced in both sides of the HP-UHP zone, which formed the Early Devonian gneissic granite with the characteristics of intraplate cracking. The zircons from the gneissic granite yielded a U-Pb isotopic age about 400 Ma [3, 12], marking the completion of the Caledonian collisional orogeny in the NQSB.
In conclusion, the Zhongwunongshan Group was deposited during the period from the late Early Silurian to the early Early Devonian (434–407.9 Ma), when the North Qaidam was in the orogenic stage of the end of the early Paleozoic. Its provenance mainly came from the uplifting and erosion of the Yuqia-Shaliuhe HP-UHP metamorphic belt and the Tanjianshan ophiolite-volcanic island arc belt of the NQSB. Furthermore, the Zhongwunongshan Group was located in the back-arc area to the Early Paleozoic Tanjianshan volcanic island arc belt of North Qaidam. With this information, it suggests that the Zhongwunongshan Group in the ZWSB and adjacent area is obviously dominated by the intense collisional orogeny of the North Qaidam in the end of the Early Paleozoic, which formed in the late Early Paleozoic back-arc basin.
6 Conclusion
Our new data allow the following major conclusions:
The detrital zircon U-Pb dating results of the Zhongwunongshan Group showed two major populations. The first was Neoproterozoic (966-725 Ma) with a ∈Hf(t) = −15.9 to 9.5, and the other was late Early Paleozoic (460-434 Ma) with a ∈Hf(t) = −9.6 to −3.1. Based on the regional studies, the dominated provenanceswere found to be the Neoproterozoic granitic gneiss of the Yuqia-Shaliuhe HP-UHP metamorphic belt and the late Early Paleozoic granites of the Tanjianshan ophiolite-volcanic arc belt in the NQSB.
In combination with previous research, the youngest detritus zircon ages of 434 Ma suggest that the Zhongwunongshan Group was deposited in the back-arc sedimentary basin associated with the Caledonian collisional orogeny of the NQSB during the Middle Silurian-Early Devonian (434–407.9 Ma)
Acknowledgement
We are grateful to Mr Dongdong Yu, Suyang Jiang and Kai Li for their help during the zircon U-Pb and Lu-Hf analyses. This study was financially supported by the subject of National Key R&D Program of China (subject No.2017YFC0602806) and the National Natural Science Foundation of China (grant number 4157021100).
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- Constraints of nonseismic geophysical data on the deep geological structure of the Benxi iron-ore district, Liaoning, China
- Mechanical analysis of basic roof fracture mechanism and feature in coal mining with partial gangue backfilling
- The violent ground motion before the Jiuzhaigou earthquake Ms7.0
- Landslide site delineation from geometric signatures derived with the Hilbert–Huang transform for cases in Southern Taiwan
- Hydrological process simulation in Manas River Basin using CMADS
- LA-ICP-MS U–Pb ages of detrital zircons from Middle Jurassic sedimentary rocks in southwestern Fujian: Sedimentary provenance and its geological significance
- Analysis of pore throat characteristics of tight sandstone reservoirs
- Effects of igneous intrusions on source rock in the early diagenetic stage: A case study on Beipiao Formation in Jinyang Basin, Northeast China
- Applying floodplain geomorphology to flood management (The Lower Vistula River upstream from Plock, Poland)
- Effect of photogrammetric RPAS flight parameters on plani-altimetric accuracy of DTM
- Morphodynamic conditions of heavy metal concentration in deposits of the Vistula River valley near Kępa Gostecka (central Poland)
- Accuracy and functional assessment of an original low-cost fibre-based inclinometer designed for structural monitoring
- The impacts of diagenetic facies on reservoir quality in tight sandstones
- Application of electrical resistivity imaging to detection of hidden geological structures in a single roadway
- Comparison between electrical resistivity tomography and tunnel seismic prediction 303 methods for detecting the water zone ahead of the tunnel face: A case study
- The genesis model of carbonate cementation in the tight oil reservoir: A case of Chang 6 oil layers of the Upper Triassic Yanchang Formation in the western Jiyuan area, Ordos Basin, China
- Disintegration characteristics in granite residual soil and their relationship with the collapsing gully in South China
- Analysis of surface deformation and driving forces in Lanzhou
- Geochemical characteristics of produced water from coalbed methane wells and its influence on productivity in Laochang Coalfield, China
- A combination of genetic inversion and seismic frequency attributes to delineate reservoir targets in offshore northern Orange Basin, South Africa
- Explore the application of high-resolution nighttime light remote sensing images in nighttime marine ship detection: A case study of LJ1-01 data
- DTM-based analysis of the spatial distribution of topolineaments
- Spatiotemporal variation and climatic response of water level of major lakes in China, Mongolia, and Russia
- The Cretaceous stratigraphy, Songliao Basin, Northeast China: Constrains from drillings and geophysics
- Canal of St. Bartholomew in Seča/Sezza: Social construction of the seascape
- A modelling resin material and its application in rock-failure study: Samples with two 3D internal fracture surfaces
- Utilization of marble piece wastes as base materials
- Slope stability evaluation using backpropagation neural networks and multivariate adaptive regression splines
- Rigidity of “Warsaw clay” from the Poznań Formation determined by in situ tests
- Numerical simulation for the effects of waves and grain size on deltaic processes and morphologies
- Impact of tourism activities on water pollution in the West Lake Basin (Hangzhou, China)
- Fracture characteristics from outcrops and its meaning to gas accumulation in the Jiyuan Basin, Henan Province, China
- Impact evaluation and driving type identification of human factors on rural human settlement environment: Taking Gansu Province, China as an example
- Identification of the spatial distributions, pollution levels, sources, and health risk of heavy metals in surface dusts from Korla, NW China
- Petrography and geochemistry of clastic sedimentary rocks as evidence for the provenance of the Jurassic stratum in the Daqingshan area
- Super-resolution reconstruction of a digital elevation model based on a deep residual network
- Seismic prediction of lithofacies heterogeneity in paleogene hetaoyuan shale play, Biyang depression, China
- Cultural landscape of the Gorica Hills in the nineteenth century: Franciscean land cadastre reports as the source for clarification of the classification of cultivable land types
- Analysis and prediction of LUCC change in Huang-Huai-Hai river basin
- Hydrochemical differences between river water and groundwater in Suzhou, Northern Anhui Province, China
- The relationship between heat flow and seismicity in global tectonically active zones
- Modeling of Landslide susceptibility in a part of Abay Basin, northwestern Ethiopia
- M-GAM method in function of tourism potential assessment: Case study of the Sokobanja basin in eastern Serbia
- Dehydration and stabilization of unconsolidated laminated lake sediments using gypsum for the preparation of thin sections
- Agriculture and land use in the North of Russia: Case study of Karelia and Yakutia
- Textural characteristics, mode of transportation and depositional environment of the Cretaceous sandstone in the Bredasdorp Basin, off the south coast of South Africa: Evidence from grain size analysis
- One-dimensional constrained inversion study of TEM and application in coal goafs’ detection
- The spatial distribution of retail outlets in Urumqi: The application of points of interest
- Aptian–Albian deposits of the Ait Ourir basin (High Atlas, Morocco): New additional data on their paleoenvironment, sedimentology, and palaeogeography
- Traditional agricultural landscapes in Uskopaljska valley (Bosnia and Herzegovina)
- A detection method for reservoir waterbodies vector data based on EGADS
- Modelling and mapping of the COVID-19 trajectory and pandemic paths at global scale: A geographer’s perspective
- Effect of organic maturity on shale gas genesis and pores development: A case study on marine shale in the upper Yangtze region, South China
- Gravel roundness quantitative analysis for sedimentary microfacies of fan delta deposition, Baikouquan Formation, Mahu Depression, Northwestern China
- Features of terraces and the incision rate along the lower reaches of the Yarlung Zangbo River east of Namche Barwa: Constraints on tectonic uplift
- Application of laser scanning technology for structure gauge measurement
- Calibration of the depth invariant algorithm to monitor the tidal action of Rabigh City at the Red Sea Coast, Saudi Arabia
- Evolution of the Bystrzyca River valley during Middle Pleistocene Interglacial (Sudetic Foreland, south-western Poland)
- A 3D numerical analysis of the compaction effects on the behavior of panel-type MSE walls
- Landscape dynamics at borderlands: analysing land use changes from Southern Slovenia
- Effects of oil viscosity on waterflooding: A case study of high water-cut sandstone oilfield in Kazakhstan
- Special Issue: Alkaline-Carbonatitic magmatism
- Carbonatites from the southern Brazilian Platform: A review. II: Isotopic evidences
- Review Article
- Technology and innovation: Changing concept of rural tourism – A systematic review