Gold vein mineralogy and oxygen isotopes of Wadi Abu Khusheiba, Jordan

Mariam A. Mosleh; Muhammad H. Roselee; Jasmi H. Abd Aziz; Ahmed H. Al-Shorman; Mahmoud H. Al Tamimi

doi:10.1515/geo-2025-0814

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Gold vein mineralogy and oxygen isotopes of Wadi Abu Khusheiba, Jordan

Mariam A. Mosleh , Muhammad H. Roselee , Jasmi H. Abd Aziz , Ahmed H. Al-Shorman and Mahmoud H. Al Tamimi

Published/Copyright: May 28, 2025

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From the journal Open Geosciences Volume 17 Issue 1

Abstract

Background

One of the best-studied subjects in the area is gold mineralization, and researchers have focused on the veins, their direct weathering products, or fluid inclusion analyses. Abu Khusheiba gold deposits in Jordan were characterized as epithermal deposits, and the wadi sediments below were investigated in some studies. Although epithermal mineralization is confirmed at Wadi Abu Khusheiba, part of the southern Jordanian Aheimer Volcanic Suite, the source of mineralizing fluids is uncertain. Among the most critical scientific issues is whether the fluids are magmatic, meteoric, or mixed, and what it would mean for gold deposition and resource potential. Moreover, the area lacks comprehensive geochemical and isotopic studies that would reveal fluid evolution, styles of alteration, and metal transport mechanisms. Stable isotope research (e.g., oxygen) in conjunction with mineralogical studies can shed light on mineralization sources and environments – addressing an important knowledge gap. Economically, fluid evolution knowledge is required to evaluate the future gold exploration potential of the Abu Khusheiba area.

Results

In accordance with stable isotope data (δ¹⁸O: 10.8 to 16.4‰), the fluids have a magmatic source with negligible meteoric water interaction. The evidence for a low-sulfidation epithermal system with constant state hydrothermal conditions comes from banded colloform quartz textures and potassic alteration. Such evidence enhances regional mineral exploration strategies as well as new ore-forming process understanding.

Keywords: oxygen isotope; magmatic; hydrothermal alteration; quartz textures; epithermal gold

1 Introduction

Gold deposits are commonly categorized based on formation temperature and depth, leading to classifications such as epithermal, mesothermal, and hypothermal. Recently, advances in analytical techniques have emphasized the genetic mode or fluid sources in distinguishing gold deposit types, including metamorphic, meteoric, evolved meteoric, and magmatic categories [1,2,3]. Studies focusing on oxygen and hydrogen isotopes have proven valuable for delineating the pathways and origins of hydrothermal fluids [4].

The properties of ore deposits – such as form, mineralogy, texture, and alteration zones – understanding mineralization relies on the properties of ore deposits [5]. Hydrothermal ore deposits significantly contribute to global gold resources, with the gold deposits in Abu Khusheiba, Jordan, recognized as epithermal [6]. The Aheimer Volcanic Suite of the Araba Complex in southern Jordan contains notable occurrences of gold, reaching concentrations of up to 15 g/t. Comprising effusive and porphyritic rhyolite with subordinate andesite, this suite hosts thin gold-bearing veins that extend for kilometers [7].

At Wadi Abu Khusheiba, the primary gold mineralization lies within a quartz vein, intermittently traceable over approximately 800 m, with a thickness of 0.3–1 m. The mineralization presents as drusy quartz crystals, fine silica with devitrification textures, and opalescent silica [6].

This study aims to provide insight into the source and genesis of ore-forming fluids in the Abu Khusheiba area, specifically through mineralogical and oxygen isotope analyses. By examining these characteristics, the study contributes to a more comprehensive understanding of the mineralization trends associated with the gold-vein-hosting rocks in southern Jordan [8].

Quartz veins and epithermal gold mineralization may be discovered in the Wadi Abu Khusheiba region of southern Jordan, which is part of the Aheimer Volcanic Suite [6]. However, there are still significant scientific questions about the fluid source, mineralization processes, and genetic model of the deposit despite earlier geological and geochemical studies. Determining whether the mineralizing fluids came from magmatic, meteoric, or mixed sources is one of the main obstacles since it has a big influence on exploration plans and resource evaluations [9]. Furthermore, the stable isotope composition of hydrothermal fluids has not been fully investigated, even though structural and petrographic investigations have shed important light on the characteristics of the host rocks and alteration patterns. Although oxygen isotopes are essential indicators for determining the origins and development of fluids, no previous study has methodically recorded δ¹⁸O values for quartz veins in this area. To close these gaps and restrict the fluid development and ore deposition mechanisms, this work integrates petrographic, mineralogical, and oxygen isotope investigations [10]. The findings will improve knowledge of Abu Khusheiba’s gold mineralization and offer a geochemical foundation for further research.

1.1 Geological setting and the geology of the study area

The research area of Wadi Abu Khusheiba lies south Wadi Araba, located around 100 km north Aqaba city and around 250 km south Amman city (Figure 1). Its boundaries are defined by the following coordinates (WGS): 35°31′83.39″ latitude, 30°27′92.07″ longitude, and 35°26′53.57″ latitude, 30°23′50.31″ longitude. The Arabian Shield (AS), which makes up about 10% of Jordan’s total land area, exposes in the southern part, along the Arabian Plate’s northern border [11].

Figure 1

General geological map of Jordan illustrates the location of study area and distribution of Jordan’s main rock based on geological age (after Alnawafleh et al. [21]; Abed [22]).

The orebodies’ exact occurrences, forms, and grades are among the mineralization aspects that must be described in detail to provide a thorough geological description of the Wadi Abu Khusheiba gold deposit [12]. According to earlier research, structurally controlled quartz veins that span about 800 m in an NNE–SSW orientation and with thicknesses varying from 0.3 to 1 m house the major gold mineralization [7]. The mineralization mostly manifests as scattered gold in vuggy quartz, sporadic appearances in brecciated and broken vein segments [6]. According to reports, the orebody’s gold grades range from 15 g/t to more, especially in areas with significant hydrothermal alteration [6]. Furthermore, ore deposition is significantly impacted by the structural control imposed by the NNW-trending shear zones, which affects the continuity and direction of the gold-bearing veins [13]. A low-sulfidation epithermal system is compatible with the spatial distribution of gold inside these veins, which points to many pulses of mineralizing fluid action. Together with geochemical markers like δ¹⁸O values between 10.8 and 16.4‰, the existence of quartz-adularia alteration lends credence to the region’s ore-forming fluids’ magmatic-hydrothermal origin [14].

The basement rocks in the southwest region of Jordan extend from the AS which is a portion of the Arabian Nubian Shield, which is divided by the Red Sea Rift zone between the African plate as the Nubian Shield (NS) and the AS on the Arabian plate [15].

These exposed rocks of the AS in southeast Jordan are divided into two groups: the Araba Complex is defined by alkaline rhyolitic volcanism and minor coeval granites with an approximate age of 605–550 Ma, and the Aqaba Complex is primarily composed of calc-alkaline plutonic rocks of probable age range 800–605 Ma cut by various extensive dykes (Figure 2). Late Proterozoic igneous and metamorphic rocks make up these two complexes [16].

Figure 2

(a) Geological map of the Aqaba Complex and (b) geological map of the Araba Complex, in southwest Jordan (After Powell et al. [19], Figure 2).

Basement rocks in Aqaba city and Araba Complexes consist of metavolcanic, metasedimentary, gneiss, and migmatite belts, which are intruded by post-tectonic granites and granodiorite in a volcanic arc setting [17]. The two Complexes are separated by a regional unconformity (peneplanation) defined by the Saramuj Conglomerate.

The rocks of the Araba Complex are exposed only in the Wadi Araba and end at a regional erosional unconformity that dates to the Lower Cambrian, known as the Ram Unconformity [18]. Above this, unconformity rests the Salib Sandstone that represents the lower rock unit of the Ram Group. The main target for precious metal research in the bottom part of Jordan’s Arabain Shield is the Aheimir Volcanic Suite, which is part of the Araba Complex [19].

This suite, oriented north-northeast, spans a 70-km-long belt with a width of 2–4 km, and its volcanic activity is estimated to have ceased around 540 Ma [7].

The four units that comprise the Au-bearing vein are agglomerates and rhyolites from the Aheimir Volcanic Suite (late Proterozoic to early Cambrian): (1) Rhyolite Qusayb, the oldest eruption phase; (2) The Musaymir Effusive, comprising rhyolitic tuff, ignimbrites, agglomerates, volcanic breccia, and rhyolitic lava; (3) Mufarqad Conglomerate, primarily conglomerates with elements from older Aheimir units to granites and metamorphic rocks; and (4) AlBayda Quartz Porphyry, the youngest phase of volcanism (Early Cambrian age), consisting mainly of quartz, feldspar, and rhyolite porphyry rocks [7].

The Musaymir Effusive rocks, which house the Au-bearing vein in the Wadi Abu Khusheiba area, predominantly consist of xenolithic agglomerate, rhyolites, granites, granodiorite, tuff, and metamorphic rocks xenoliths. However, a singular zircon SIMS date for the flow-folded rhyolites (Musaymir Effusives) indicated an age of 598 ± 5 Ma. The youngest eruption phase of Musaymir volcanism is breccia, covering the top 20 m of the unit [7]. These volcanic breccia overlay the Au-bearing vein, especially in the northern section of the area. The Au-bearing vein is associated with the Qusayb Rhyolite Unit in the southern half of the mineralized zone [20].

2 Methods

2.1 Field sampling and sample preparation

A total of 24 samples, including quartz veins and hydrothermally altered rocks, were collected from various locations within the Wadi Abu Khusheiba area, with a focus on zones showing clear signs of hydrothermal alteration. Fourteen quartz vein rock samples were cut and polished into thin units for petrographic analysis, while a portion of each sample was ground to a powder (less than 63 μm) using an agate ball mill or a jaw crusher for mineralogical analysis through X-ray diffraction (XRD).

2.2 Petrographic analysis

Thin sections we analyzed thin sections using a Leica 020-522.101 DM/LSP polarizing microscope from Leica, equipped with a Leica ICC50 HD digital camera. The microscope operated at a main voltage of 12 V with a maximum power consumption of 30 W, allowing for detailed examination and documentation of mineral structures.

2.3 Analysis of XRD

XRD analysis was carried out to characterize hydrothermal alteration and rock-forming minerals. The powdered samples were analyzed using a Shimadzu X-ray diffraction-600, with Cu Kα radiation over a 5–70° 2θ angle range, at a wavelength of 1.54178 Å, 45 kV operating voltage, and 40 mA operating current. The minerals present in the samples were identified using High-Score plus software.

Table 1 provides a summary of the parameters utilized in the scanning X-ray diffractometer investigation.

Table 1

Parameters were used during the scanning X-ray diffractometer

X-ray generator	Cu Kα radiation
Angle range	(5–70°) 2θ
Wavelength	1.54178 Å
Working power	1.8 kW
Working voltage	45 kV
Working current	40 Ma

Note: The true value for standard NBS 28 is +9.64 + −0.06.

2.4 Reflected light microscope analysis

To examine ore minerals, a Carl Zeiss reflected light microscope was used, equipped with a Carl Zeiss Micro Imaging GmbH 37081 digital camera. This setup enabled detailed analysis of mineral assemblages and textural relationships within the samples.

2.5 Analysis of oxygen-stable isotopes

Analysis of oxygen-stable isotopes was conducted at ALS Arabia, Dammam, Saudi Arabia, using powdered quartz samples (5–20 mg per sample) to produce reproducible δ¹⁸O values reported in permille (‰) relative to Vienna Standard Mean Ocean Water (VSMOW).

For verification of the precision and repeatability of oxygen isotope analysis, a standard reference material, NBS-28 (National Bureau of Standards’ quartz standard), was analyzed along with unknown quartz samples. The δ¹⁸O value of NBS-28 calculated was 9.60 ± 0.06‰ that is in extremely close agreement with the recommended international standard value of 9.64 ± 0.06‰. This such a great level of concordance confirms the precision of our analytical method. The consistency of the certified and measured values certifies the reliability and stability of the procedures of stable isotope analysis used in this study. Such certification adds confidence to the obtained δ¹⁸O values for Abu Khusheiba quartz veins, which can be well interpreted in terms of hydrothermal fluid sources.

The oxygen isotope composition (δ¹⁸O) calculated for Abu Khusheiba quartz samples is presented in Table 2.

Table 2

Oxygen isotope data

Sample ID	δ¹⁸O‰ vs VSMOW
Vm1	10.8
Vm3	16.4
Vm5	12.5
Vm6	11.9
NBS28 (standard ID)	9.6
St. dev.	0.4

The precision of measurements was 0.4‰. Oxygen was extracted following the thermal fluorination method described by Clayton and Mayeda in 1963, with oxygen transformed to CO₂ and measured on a dual-inlet mass spectrometer. For calculating δ¹⁸O values of hydrothermal fluid, calibrated δ¹⁸O values of minerals (say, quartz) were back-calculated by the respective mineral–water fractionation equation on an estimated temperature of formation. The calculated δ¹⁸O values of the fluid may then be applied for the reconstruction of the ore-forming fluid’s oxygen isotope composition.

3 Results

3.1 Mineralogy

3.1.1 Primary minerals

The Aheimir Volcanic Suite is characterized by quartz vein hosting agglomerates and rhyolites. Wadi Abu Khusheiba’s gold mineralization is connected to a brecciated vein that is banded and rich in silica, often observed as disseminated aggregates within vugs and open spaces. Mineralization tends to be localized within geological structures and displays numerous distinctive features.

During field investigations, a significant vein associated with the NNW-trending shear zone, dipping towards the northeast, was identified. The most protuberant structural element in the research area is the NNE–SSW-trending Wadi Araba Fault [23].

The gold-bearing vein constitutes a linear zone extending up to 700 m in length. The width of the mineralized zone varies between 0.4 and 10 m, tapering off in the southern portion due to faulting and the presence of dense dykes in the vicinity [24].

The results of both petrographic and XRD analyses of the examined rock samples indicate that quartz is the most prevalent mineral, occurring primarily as both a primary and replacement mineral across all samples. It shows up as anhedral to subhedral crystal formations and as irregular, fine-grained, microcrystalline aggregates and cryptocrystalline grains. Alkali feldspar, predominantly orthoclase, ranks as the second main mineral in all the studied vein rocks (Figure 3).

Figure 3

Polarized light photomicrographs (XPL) depict the primary minerals found in the host rock vein samples. (a) Mosaic and cryptocrystalline quartz, (b) orthoclase, (c) aplite fragments with cryptocrystalline quartz, and (d) opaque minerals. Abbreviations: Aplt frg = aplite fragment, op = Opaque, orth = orthoclase, cryp = cryptocrystalline, Qz = Quartz (After Mosleh et al. [25], Figure 4).

The vein rock sample sections show a brecciated facies, which is made up of rock pieces, particularly a lot of aplite fragments. A cryptocrystalline substance, most likely devitrified volcanic glass with a quartz feldspathic composition and extensively saturated with fine opaque minerals, holds these fragments together. Under a polarized microscope, dark brown veins and fissures packed with opaque minerals and iron oxides were seen in the vein rock samples, and they were determined to be accessory minerals. Pyrite and chalcopyrite emerge as the main sulfides observed within the quartz/silica vein (Figure 3).

Mineragraphic analysis conducted using Carl Zeiss reflected light microscope designates that the polished sections predominantly contain metallic minerals such as pyrite, chalcopyrite, gold, and iron oxides. Gold is observed as finely disseminated granular grains within a quartzose gangue, presenting in micron-scale dimensions across the examined samples. This native gold exhibits a yellow hue under natural light when viewed at a microscopic scale. In contrast, within the aplitic granite fragments, pyrite is widely distributed, usually discovered in vugs and open voids, while goethite may have formed either wholly or partially from pyrite. Additionally, micronic granules of chalcopyrite are interspersed, some of which exhibit complete alteration (Figure 4).

Figure 4

Reflected light photomicrographs depicting the composition of ore minerals. Abbreviations: Gd = Gold, py = pyrite, cpy = chalcopyrite.

The X-ray diffraction results of the studied samples revealed that quartz predominates as the major mineral phase, with orthoclase existing as a minor mineral. Traces of chlorite, hematite, sericite, calcite, and adularia were also detected. These findings were corroborated by thin sections of the samples, which contain quartz, orthoclase, and sericite minerals (Figure 5). The major element oxide results of the rock-hosting gold vein, particularly for the main oxides – SiO₂ (74.7–83.4%), Al₂O₃ (7.0–13.3 wt%), K₂O (5.3–8.8 wt%), Fe₂O₃ (0.5–3.5 wt%), Na₂O (0.10–1.1 wt%), and CaO (0.11–1.2 wt%) – corroborate the findings from petrographic analysis and XRD.

$Figure 5 Diffract graphs of selected representative samples. Abbreviations: Qz: Quartz, Orth: orthoclase, Cal: calcite, Chl: Chlorite, Ser: Sericite, Hem: hematite, Adu: Adularia.$

Figure 5

Diffract graphs of selected representative samples. Abbreviations: Qz: Quartz, Orth: orthoclase, Cal: calcite, Chl: Chlorite, Ser: Sericite, Hem: hematite, Adu: Adularia.

3.1.2 Alteration minerals

Quartz vein in the study area is commonly related to the alteration process, which has been identified through field observations and confirmed by petrographic examination and XRD analysis of altered rock samples. Common hydrothermal minerals found in different alteration zones include quartz, adularia, sericite, hematite, chlorite, and calcite.

Quartz is a primary mineral found in the Steward rock veins but can also take place as a replacement, typically in the form of cryptocrystalline quartz [26]. Most quartz replaced the groundmass and appeared as fine anhedral interlocking grains, and sometimes formed as micro- to cryptocrystalline crystals (Figure 6a).

Figure 6

Polarized light photomicrographs (XPL) showing the alteration minerals of the rock chip samples: (a) altered quartz as cryptocrystalline (cryp), (b) adularia and sericite, and (c) and (d) dark vein (microcracks) with hematite and goethite iron oxides.

Adularia, a variety of orthoclase, acts as a secondary mineral resulting from the alteration of K-feldspar. Adularia forms distinctive rhombohedral crystals (Figure 6b). Plagioclase minerals (andesine and albite), which have been altered to sericite, are often associated with fine crystalline quartz (Figure 6b). Sulfide minerals, such as pyrite and chalcopyrite, are changed entirely or in part to goethite. Hematite formed as dissemination throughout the quartz vein sample or as veinlets interstitially within the matrix with fine grains or along microcracks (Figure 6c and d).

Field evidence showed that the wall rocks exhibited sericite, which often appears as a silvery or pale yellow-colored mineral, while hematite shows reddish-brown color. Iron oxides, specifically in the form of goethite and hematite, are notable features in nearly all the samples when viewed under a reflected microscope (Figure 4). The alteration of pyrite and chalcopyrite is the main source of goethite.

3.1.3 Vein textures

A variety of vein textures were observed in mineralization veins, and texture categories are identified by factors for example grain size and quartz shape. Quartz textures are classified into three groups: textures formed during the first deposition of the phase (primary), textures associated with recrystallization, and textures associated with the replacement of initially precipitated material. Primary growth textures reflect the first open-space vein fill [27]. Some of these textures can be easily seen in hand specimens, others require microscopic examination, and yet others can only be seen under petrographic microscope.

The most prevalent quartz textures found in the Abu Khusheiba mineralization vein during fieldwork in the research region are crustiform, banded colloform, massive, vast formless quartz/silica, mosaic, and comb textures (Figure 7).

Figure 7

Polarized light photomicrographs (XPL) showing quartz vein textures. (a) Comb texture and (b) mosaic texture.

Quartz with mosaic texture is the most prevalent mineral texture seen under microscope, and aggregates of crystalline to microcrystalline quartz crystals with interpenetrating grain boundaries give this texture its distinctive appearance [28], which is only distinguished under crossed polars.

Crustiform and banded textures mostly occur in quartz veins that bear gold and the primary growth textures of mineralized veins. These textures consist of successive, narrow (up to a few millimeters), subparallel bands that can be identified by variations in texture, mineral proportions, and/or color; typically, banding develops symmetrically from both walls of a fissure [29].

Colloform is a primary growth texture that refers to a condition in which a mineral or mineral aggregates exhibit mixed spherical, botryoidal, reniform, and mammillary shapes on its exterior [30]. Colloform texture is characterized by distinctive spherical shapes and continuous banding. The formation of these rounded structures is thought to result from processes involving a silica precursor. One proposed mechanism is the precipitation of silica gel in open spaces [31], surface tension, a fluid feature induced by intermolecular forces close to the surface, tends to restructure all non-spherical surfaces into a spherical, lowest free energy configuration is thought to be the process’ governing component, the second process is the crystallization of silica gel to separate contaminants, the main prerequisite for this process is a relatively slow rate of impurity diffusion compared to the rate of crystal development, which often happens in viscous silica gel with impurities [32].

Comb texture is also considered primary growth texture, where geometrical selection must effectively proceed, geometrical selection is a type of competition for space between adjacent crystals, which results in the growth of only those crystals where the direction of maximum rate of growth is perpendicular to the growth surface, and this requires relatively slow changing conditions in an open space during crystal growth [33].

3.2 Stable isotope of oxygen

Stable isotope of oxygen analyses were conducted on four representative distinct samples collected from Abu Khusheiba quartz vein.

The isotopic makeup of the ore-forming fluids throughout the mineralization process does not directly represent the δ¹⁸O values of hydrothermal quartz alone. Rather, the temperature-dependent fractionation equation between quartz and water must be used to convert these data to δ¹⁸O_fluid [34]. The empirical formula may be used to calculate the fractionation of oxygen isotopes in water and quartz:

δ 18 O fluid = δ 18 O quartz − a quartz − water,

where the factor of fractionation, α _quartz – water, is temperature dependent. Homogenization temperatures in the Abu Khusheiba area vary from 200 to 280°C, according to earlier microthermometry investigations of fluid inclusions [35]. Based on these temperature estimations, the hydrothermal fluids’ computed δ¹⁸O values should fall between +5.8 and +7.9‰. This is in line with a magmatic origin that has been slightly impacted by meteors.

With the presence of potassic alteration and stable mineral assemblages suggestive of a magmatic-hydrothermal environment, these computed δ¹⁸O_fluid values offer a more realistic depiction of the hydrothermal system and validate that the gold-bearing fluids at Abu Khusheiba were predominantly magmatic.

The selection of these samples ensured representation across all veins. The findings exhibited a variation in the range of 10.8–16.4‰, with an average of 12.9‰. The δ¹⁸O‰ values for the quartz vein are provided in Table 2.

4 Discussion

4.1 Mineralogy

4.1.1 Hydrothermal alteration processes and fluid-rock interaction

Chlorite, sericite, and hematite are among the alteration assemblages found in the Abu Khusheiba region that show hydrothermal fluid contact with the host rocks at low-sulfidation epithermal conditions. Potassic alteration and the connection of quartz and adularia point to a stable hydrothermal system connected to a source of magmatic fluid.

4.2 Textural signs of the evolution of hydrothermal fluids

Multi-stage fluid development is reflected in the banded, colloform, and comb-like vein textures seen in quartz. While comb textures show fast quartz crystallization from supersaturated hydrothermal fluids, crustiform textures reveal episodic fluid inflow. These textural characteristics align with patterns of fluid development found in other epithermal gold deposits.

4.3 Isotopic limitations on sources of hydrothermal fluids

The fundamental magmatic-hydrothermal origin of quartz is indicated by its δ¹⁸O values, which vary from 10.8 to 16.4‰. A magmatic-dominated hydrothermal system with little participation of meteoric water is suggested by the δ¹⁸O values of hydrothermal quartz (10.8–16.4‰) and the computed δ¹⁸O_fluid values (5.8–7.9‰). Nonetheless, the very small range of δ¹⁸O readings suggests a stable hydrothermal regime with little variation in temperature and fluid supply. The fast isotopic exchange between the ore fluids and the surrounding steward rocks, on the other hand, usually results in greater δ¹⁸O fluctuations in deposits that undergo considerable meteoric water input or episodic boiling episodes [46]. Abu Khusheiba’s absence of severe δ¹⁸O depletion indicates that the magmatic source kept the hydrothermal fluids buffered, with only slight mixing with shallow meteoric water. This aligns with low-sulfidation epithermal deposits that are structurally regulated, where fluid evolution takes place in a comparatively closed environment with only limited meteoric water effect [47]. By combining the isotopic studies of sulfur (δ³⁴S) and hydrogen (δD), it would be possible to more accurately differentiate between meteoric and magmatic contributions and provide further restrictions on fluid development.

The δ¹⁸O_fluid values were determined to be +5.8 to +7.9‰ using a fractionation equation for quartz-water systems at projected mineralization temperatures (200–280°C), indicating a mostly magmatic source with a small meteoric effect. Table 3 summarizes the differences between the Abu Khusheiba gold deposit and comparable deposits in other regions in terms of δ¹⁸O_SMOW values, salinity, and ore-forming fluid sources.

Table 3

δ¹⁸O_SMOW data, salinity, and ore-forming fluid sources from the Abu Khusheiba gold deposit and other region

Researcher	Area	Range values of salinity (wt% NaCl equiv)	Range of values of δ¹⁸O_SMOW	Source of ore-forming fluids
Author	Abu Khusheiba. South Jordan	1.5–7 wt% (Al-Hwaiti et al. [6])	10.8–16.4‰	Magmatic
Rakhimov et al. [36]	Khudolaz Area, Southern Urals	8–12 wt%	16.1–18.2‰	Magmatic
Liu et al. [37]	Jiaodong Peninsula, Eastern China	0.35–10.4 wt%	9.7–15.1‰	Magmatic
Hammond et al. [38]	Morila Mine, Mali, West Africa	12–16 wt%	14.3–15.8‰	Magmatic origin
Barbosa [39]	Vetas, Antander, Colombia	1.2–18.6 wt%	11.2–15.7‰	Magmatic waters dominant
Lv et al. [40]	Jiaodong Peninsula, China	0.18–17.00 wt%	6.8–9.3‰	Magmatic
		1.23–13.26 wt%
		28.59–32.87 wt%
Lemarchand et al. [41]	South Armorican, France	0–0.5 wt%	Down to −2‰	Meteoric
Ünal-İmer et al. [42]	Çanakkale, NW Turkey (Kartaldağ)	0–1.7 wt%	δ¹⁸O_quartz: 7.93–8.95‰ and δ¹⁸O_H₂O: −7.95 to 1.49‰	Meteoric
Ünal-İmer et al. [42]	Çanakkale, NW Turkey (Madendağ)	0–1.7 wt%	δ¹⁸O_quartz: 9.55–18.19‰ and δ¹⁸O_H₂O: −2.97 to 5.54‰	Mixing of magmatic and meteoric
Li et al. [43]	Fujian Province, southeast China	0.4–2.6 wt%	−5.7 and −3.8‰	Mixing of magmatic and meteoric
Carrillo-Rousa et al. [44]	El Sauce district, central-northern Chile	1.6–6.9 wt%	3–10‰	Mixing of magmatic and meteoric
Tuakia et al. [45]	Salu Bulo, Sulawesi, Indonesia	3.0–8.5 wt%	+5.8 and +7.6‰	Mixing of magmatic and meteoric

Fluid inclusion and isotopic analyses have confirmed magmatic contributions with limited meteoric interaction in the Jinji gold deposit (Jiangnan Orogen, China) [48] and the Longkou-Tudui gold deposit (Jiaodong Peninsula, China) [47], exhibiting similar isotopic trends. The Abu Khusheiba deposit’s categorization as a structurally regulated low-sulfidation epithermal deposit is supported by the consistent δ¹⁸O readings, which indicate a stable hydrothermal system with little fluid mixing.

5 Conclusion

Based on the alteration mineral assemblage (quartz, adularia, sericite, hematite, chlorite, and calcite), and the observed wall-rock alterations, which consist of silicic, potassic, and propylitic alterations, it is evident that these minerals have undergone an alteration due to interactions with near-neutral pH fluids. This alteration is crucial for distinguishing low-sulfidation epithermal system types.

Different textural of quartz can be instrumental in identifying the nature and origin of veins and associated mineral systems. The quartz in the veins of Abu Khusheiba was formed as banded colloform, crustiform, mosaic, and comb textures, which indicate characteristics of low-sulfidation epithermal systems. Additionally, through the analysis of stable oxygen isotopes the sources of hydrothermal fluids have been determined in the research area. The δ¹⁸O‰ values of the quartz veins in Abu Khusheiba fall within a relatively narrow range of 10.8–16.4‰, and these δ¹⁸O‰ values and low standard deviation of 0.4‰ suggest that the quartz veins likely formed under similar conditions or originated from a similar source. The δ¹⁸O values of the quartz veins in the research area are relatively high, suggesting that the quartz crystallized from fluids with a significant contribution from a magmatic origin. This study marks the first reporting of δ¹⁸O‰ isotope values for quartz veins in this area.

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Acknowledgment

Special thanks are due to Eng. Wafa’a Bakheet, a member of the Board of Commissioners of the Energy and Minerals Regulatory Commission, for her logistic support in the fieldwork. We are deeply indebted to the technical staff of the Laboratories of Faculty of Archaeology and Anthropology, Yarmouk University, for their kind help.

Funding information: Authors state no funding involved.
Author contributions: M.A.M. and M.H.R. designed the study and supervised field data collection. J.H.A.A. and A.H.A.S. conducted laboratory analyses and interpreted mineralogical data. M.H.A.T. performed statistical analysis and contributed to data interpretation. M.A.M. collaborated with all co-authors to organize the manuscript. For the author sequence, the writers used the SDC technique, meaning that the sequence reflects the declining importance of each author’s contribution.
Conflict of interest: Authors state no conflict of interest.
Data availability statement: Data corroborating the results of this investigation can be obtained upon request.

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Received: 2024-10-20

Revised: 2025-04-08

Accepted: 2025-04-21

Published Online: 2025-05-28

This work is licensed under the Creative Commons Attribution 4.0 International License.

Articles in the same Issue

https://doi.org/10.1515/geo-2025-0814

Keywords for this article

oxygen isotope; magmatic; hydrothermal alteration; quartz textures; epithermal gold

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