Comparison between thermal models across the Middle Magdalena Valley, Eastern Cordillera, and Eastern Llanos basins in Colombia

2.1.1 MMVB

It is located between the Central and Eastern Cordilleras (Figure 1) and bound by the Espíritu Santo Fault systems (north), Bucaramanga–Santa Marta (northeast), Bituima and La Salina (southeast), the Girardot folded belt (south), and Neogene sediments over the Serranía de San Lucas and the Central Cordillera (west). Its sedimentary cover ranges from the Jurassic to the present. The tectonic evolution of the MMV began with the formation of a supra-continental graben in the Jurassic, with normal faults and tectonic subsidence, allowing the deposition of continental sediments (Bocas, Jordan, Girón, and Los Santos Formations). At the beginning of the Cretaceous, a regime of extensional tectonics caused normal faults and a transgression until the Tertiary (Lisama Formation). During this phase, intermediate and basic intrusions, pyroclastic intercalations, and dacite porphyry formation occurred, extending until the Paleocene [38].

The main fold in the MMVB is the De Armas Syncline with an SSW-NNE orientation, which is considered a tight and asymmetric structure; while its western flank has dips between 18° and 30° to the northwest; the eastern flank mainly has dips from 40° to 60° to the southeast. The area is intersected by various fault systems, among which the most notable are Espiritu Santo, Santa Marta–Bucaramanga, and La Salina Faults. The Espíritu Santo is a strike-slip fault with N30E orientation and with an extension of 90 km long, and the main lineation is affected by a tertiary erosion surface [39]. The Santa Marta–Bucaramanga Fault, which is 550 km long, is a system constituted by two strike-slip faults with left-lateral movement; its orientation is N20W [40,41]. The La Salina Fault is considered a reverse fault system with a dextral strike-slip component, causing subsidence in the NE part of the MMV and serving as a boundary for the basin [38].

2.1.2 Eastern Cordillera Basin

The Eastern Cordillera Basin is located between the MMV and Eastern Llanos Basins (Figure 1), bound by the Guaicáramo Fault to the east and the Bituima and La Salina Fault systems to the west. It extends from the Quetame Massif in the south to the Perijá Range in the north, composed of rocks ranging from Proterozoic to Cenozoic ages. It has sporadic igneous bodies in the northeast and southwest. Since the Eocene, the basin has undergone folding and fracturing, shaping its current geomorphology. It is characterized by folds and faults along the eastern belt, influencing the stratigraphic arrangement. Of these folds, the most important are the following: Arcabuco Anticline composed of Jurassic sedimentary rocks, including the Palermo, Montebel, and Russia Formations [42], controlled by the Boyacá Fault. The Los Cobardes Anticline constituted of Jurassic sedimentary rocks [43] is bound to the east by the Zapatoca Fault and to the west by the El Ramo Fault [44]. The Farallones Anticline, composed of Paleozoic units [36], seems to be influenced by the ancestral Guatiquía Graben, with its formation particularly affected by the inversion of the Servitá Fault. The axis of this fold is parallel to both the Servitá Fault and the San Juanito Fault. Consequently, its origin could be attributed either entirely to inversion or to an extensional rollover that was subsequently enhanced by contraction [35]. The Guavio Anticline was formed by overlapping Miocene–Pliocene fault-bend folds and inversion of the Guaicáramo normal fault [45]. This anticline involves Carbonera, Barco, Los Cuervos, and Mirador geological formations [36]. The San Antonio Anticline with an extent that does not exceed 20 km is located at the Soapaga Block. This anticline that involves rocks of the Guadalupe Formation is considered a symmetrical narrow fold, with an axis oriented NNE-SSW, truncated both to the north and south by minor faults, and located to the east of the Betéitiva Syncline. The latter is located on the footwall of the Soapaga Fault, preserving a thick sequence of tertiary sediments [46]. The main faults in this area are the Soapaga Fault and the Boyacá Fault. The Soapaga Fault is a regional reverse fault trending NNE-SSW, forming the eastern edge of the Floresta Massif. In contrast, the Boyacá Fault is a structure trending NNE-SSE, forming the western edge of the Floresta Massif. However, apparently both faults are related to the horse-tail termination of the Bucaramanga Fault [42,46,47,48,49]. For the study of Velandia and Bermúdez [50], these faults are captured by the southern termination of the Santa Marta–Bucaramanga Fault.

2.1.3 Eastern Llanos Basin

The Eastern Llanos Basin is located between the Eastern Cordillera Basin to the west, bound by the Guaicáramo Fault System, and the Guayana Shield to the east (Figure 1). To the north, it borders the Barinas Basin and to the south with the Macarena Range and the Vaupés Arch (VA). This basin comprises rocks ranging from Proterozoic to Holocene ages. The tectonic evolution begins from the Paleozoic with the occurrence of marine deposits and normal faults. During the Mesozoic, continued opening with Jurassic–Triassic deposits in the Arauca Graben and marine sediments due to sea-level rise, which marked the beginning of a transpressive regime by subduction of the oceanic crust, leading to the uplift of the Central Cordillera and movements in the Cusiana–Tamara Fault [51]. In the Cenozoic, compressive forces uplifted the Central Cordillera, forming the mega-forearc basin, fragmenting it, and causing inversion in the Eastern Cordillera Basin and flexural subsidence in the Eastern Llanos Basin with continental sediment deposits. The Eastern Cordillera Basin is considered a sediment source for the Eastern Llanos Basin at the end of the Paleogene [52]. The Eastern Llanos Basin presents fold and fault structures primarily developed by Andean cycle tectonics.

Some representative structures of the Eastern Llanos Basin are the following: the Nunchía Syncline is an elongated structure trending N20°E with inclined flanks of 10–15°, affected by the Yopal or Pajarito Fault to the east and the Guaicáramo Fault to the west [52]. The Pajarito Fault is a regional reverse fault whose average direction is N25°E, with a fault plane to the west. The Monterralo Anticline is one of the most developed folds in terms of amplitude and structural relief, with an NE-SW trending axis, southeast-verging asymmetry, and a double plunge [53]. The most important faults for the sector studied are the following: Guaicáramo Fault is a thrust faults’ system forming the border of the Eastern Cordillera, have a general orientation of N40°E dipping into the NW in a compressive stress regime, and is affected by morphodynamic processes. The Yopal Fault is a reverse fault that bounds the foothills with the plain; its fault plane is sub-vertical, slightly inclined to the west, and cut by small strike-slip faults. This lineament affects the alluvial fans at the edge of the cordillera. For the Eastern Llanos Basin, the geological units encompass Paleocene (Los Cuervos), the Eocene Mirador, Eocene to Miocene Carbonera Formations, the Miocene León Formation, and the Miocene to Pliocene Guayabo Formation.

2.2.1 MMVB

The MMVB is filled with Mesozoic and Cenozoic successions that range from 2 to 10 km in thickness. The sequence encompasses both marine and nonmarine deposits and overlies a Proterozoic-to-lower Paleozoic basement [54]. Overlying the sparse Jurassic syn-rift deposits, the Mesozoic sequence primarily consists of sandstones, limestones, and mudstones, which reflect a widespread marine transgression. This period was later followed by a marine retreat, leading to the deposition of nonmarine strata during the Cenozoic era [55].

A regional unconformity [38,55,56,57,58] separates the MMVB into two distinct sequences. The lower sequence is made up of deformed and eroded rocks from the Paleocene and older periods, with its thickness increasing toward the east, reaching up to 2,500 m at the border with the Eastern Cordillera. Above this, the overlying sequence consists of relatively undeformed units, ranging from the Middle Eocene to the Neogene, which rest unconformably on the lower sequence.

The stratigraphic subdivision of the MMVB includes, from the oldest to the youngest, the Umir, Lisama, La Paz, Esmeraldas, Mugrosa, and Colorado Formations, followed by the Real Group and the Mesa Formation. Additional minor unconformities are likely caused by tectonic deformation related to the evolution of the Central and Eastern Cordilleras [38,57,59,60]. The La Paz, Esmeraldas, Mugrosa, and Colorado Formations were deposited in a fluvio-alluvial environment. The fluvial sequences are the most extensive deposits, consisting of coarse detrital sediments forming channel belts interlayered with fine-grained floodplain and overbank sediments [38,57,61,62]. Locally, thin lacustrine floodplain sequences have also been reported. The La Paz Formation was mainly deposited by a braided fluvial system, the Esmeraldas and Mugrosa Formations by meandering streams, and the Colorado Formation by a mix of meandering and braided fluvial systems.

2.2.2 Eastern Cordillera Basin

This basin presents a stratigraphic sequence that spans from the Paleozoic to the Cenozoic. During the Paleozoic, the Eastern Cordillera Basin was dominated by sediments of marine origin [63]. The crystalline basement is overlain by coarse-grained, nonmarine deposits, typically composed of sandstone and conglomerate, along with associated volcaniclastic materials, dating from the Middle/Late Jurassic to Early Cretaceous (Girón Group). The Lower Cretaceous marine sequence, consisting mainly of clastic facies with subordinate carbonate layers, directly overlies isolated Jurassic deposits or crystalline basement (Tibasosa Formation) [42,64]. Further up in the sequence, an Upper Cretaceous to Cenozoic clastic series records the shift from marine to nonmarine deposition, along with rapid accumulation during the period of Andean shortening and thermal subsidence [65,66]. Extended sandstone facies of Campanian, Maastrichtian, and Early Paleocene age (Guadalupe Group and Guaduas Formation) are distributed across the Eastern Cordillera and its margins [63]. The Maastrichtian to lower Paleocene Guadalupe Group and Guaduas Formation are part of a regionally extensive sandy interval that marks the final marine to nonmarine transition in the region. In the axial Eastern Cordillera, these sandstones are overlain by a mixed assemblage of fluvial and lacustrine sandstone, mudstone, and subordinate conglomerate, comprising the Paleocene Socha (Bogotá) Formation, the lower to middle Eocene Picacho (Regadera) Formation, and the upper Eocene to Oligocene Concentración (Usme) Formation. The absence of Miocene and younger deposits is thought to reflect a history of non-deposition during the Andean uplift, rather than deposition, followed by subsequent erosional removal [63].

2.2.3 Eastern Llanos Basin

Four tectonic events are recorded in the Nunchia Syncline area, controlling deposition and sedimentary environments: “pre-rift,” “syn-rift,” “post-rift,” and positive tectonic inversion. In the “pre-rift” deposits, quartz arenites with intercalations of Paleozoic shales from the Farallones Formation are found [67]. The “syn-rift” deposits are represented by the Macanal, Las Juntas, and Fómeque Formations. These formations are mainly composed of gray shales and siltstones, quartz arenites with shale intercalations, and shales with intercalations of biomicrites and biosparites [67,68]. Locally, these rocks are intruded by metamorphosed basic rocks in the Pajarito area [69].

The “post-rift” sequence begins in the Albian and extends to the Maastrichtian, where the Une, Chipaque, Guadalupe, and Guaduas Formations were deposited [66]. The Une Formation consists of gray quartz arenites with intercalations of coarse sand and thin layers of shales [70]. Stratigraphically ascending, mudstones and siltstones with sporadic lenses of fine sand with glauconite, bioturbation, and phosphatic remains are found in the so-called Chipaque Formation [68]. Overlying this formation is the Guadalupe Formation, composed of fine-grained phosphatic quartz arenites interbedded with mudstones, shales, and cherts. The last formation in the sequence is the Guaduas Formation, which consists of gray mudstones with coal layers and fine-grained quartz arenites. This formation shows erosion towards the east of the foreland basin [68,71].

Shallow marine to continental sediments during the Cenozoic indicate the shallowness of the basin and the record of the uplift of the Eastern Cordillera [72]. A basin inversion begins with systems migrating the north and east during the Paleocene (Barco and Los Cuervos Formations), west during the Middle Eocene (Mirador Formation), east during the Oligocene (lower part of the Carbonera Formation), and east during the Miocene (Guayabo Formation) [73].

4.1.1 MMVB (De Armas Syncline zone)

According to Sánchez et al. [78], the De Armas Syncline is part of the “hanging wall” zone of the La Salina Fault, characterized by the presence of gentler folds and minimal surface expression of significant faults (Figure 4). This zone has three deformation stages: the first from 45 to 30 Ma, the second from 18 to 12 Ma, and the third from 12 to 3 Ma. To contrast the interpretation of the mentioned study with petroleum system modeling, the Armas-1 pseudo-well was modeled, covering units from the Jurassic to the Lower Cretaceous.

Figure 4

Structural section with the location of the Armas-1 pseudo-well in the De Armas Syncline, at the MMVB. Source: Modified from Sánchez et al. [78]. In this figure: OS, AS, CA and VS are Opón Syncline, Armas Syncline, Cobardes Anticline, and Vélez Syncline, respectively. FT: Frontal thrust, UT: Upper backthrust, LT: Lower backthrust and LSF: La Salina Fault.

As a result of the thermal model applied for calibration, a current heat flow of 60 mW/m² was obtained (Figure 5a). Additionally, a vitrinite reflectance (%Ro) of 42% and a temperature of 162°C at the final depth were recorded (Figure 5b and c).

Figure 5

Results of calibration of the thermal model for the Armas-1 pseudo-well: (a) temperature and heat flow versus depth (m), (b) vitrinite %Ro versus depth (m), and (c) temperature versus depth (m).

The subsidence model for the study area shows sedimentation rates ranging between 1,870 and 11,070 m associated with temperatures oscillating between 25 and 234°C. The highest sedimentation rate related to a greater heating phase is observed during the Miocene, followed by a cooling phase starting at 6 Ma (Figure 6a and b). The relationship between the burial history (Figure 6a), thermal maturity (Figure 6b), and transformation rate (Figure 6c) shows a temperature increase from the Lower Cretaceous. The onset of oil window is highlighted from the Upper Cretaceous, reaching high temperatures with vitrinite reflectance (%Ro) values exceeding 2% (Figure 6c). In contrast to thermal maturity, transformation rates of 100% can be seen, describing facies in this zone that are completely depleted due to high thermal maturity (Figure 6d).

Figure 6

Relationships between (a) burial history, (b) thermal maturity, (c) vitrinite %Ro, and (d) hydrocarbon transformation rate (%) across the Armas-1 pseudo-well, for the MMVB.

4.1.2 Eastern Cordillera Basin (Soapaga Fault zone)

According to the UPTC – ANH (2021) study, the area is characterized by synclinal and anticlinal structures with NE-trending axes cut by reverse faults located to the east of the Soapaga Fault. The most important structures in this sector are associated with the Betéitiva Syncline and the San Antonio Anticline. To contrast the interpretation of the aforementioned study with petroleum system modeling, the Bolívar-P1 pseudo-well was modeled, covering units from 110 Ma (Tibasosa Formation) to the Neogene (Picacho Formation; Figure 7).

Figure 7

Seismic interpretation with the location of the Bolívar-P1 pseudo-well in the Soapaga Fault zone, axial zone of the Eastern Cordillera Basin.

As a result of the thermal model applied for calibration, a current heat flow history of 62 mW/m² was obtained (Figure 8a). Additionally, a vitrinite reflectance (%Ro) of 1.3 and a temperature of 127°C at the final depth were recorded (Figure 8b and c).

Figure 8

Results of the calibration of the thermal model for the Bolívar-P1 pseudo-well: (a) temperature and heat flow versus depth (m). (b) Vitrinite %Ro versus depth (m), and (c) temperature versus depth (m).

The subsidence model for the study area shows sedimentation rates ranging between 202 and 4,192 m and temperatures oscillating between 12 and 127°C. The highest sedimentation rate is observed during the Neogene (Figure 9a and b). The relationship between the burial history, thermal maturity, and transformation rate shows a temperature increase from the Paleocene. The onset of the oil window is evident from the Eocene for the Tibasosa Formation and from the Oligocene for the Chipaque Formation (Figure 9c). In contrast to thermal maturity, transformation rates of 90% for the Tibasosa Formation and 61% for the Chipaque Formation are observed, describing facies in this zone with the capacity to generate HCs (Figure 9d).

Figure 9

Relationships between (a) burial history, (b) thermal maturity, (c) vitrinite %Ro, and (d) hydrocarbon transformation rate (%) across the Bolívar-P1 pseudo-well.

4.1.3 Eastern Llanos Basin (Nunchía Syncline zone)

The Nunchía Syncline corresponds to the foothill area located between the Guaicáramo Fault and the Yopal Fault (Figure 10) [37]. According to the geological evolution model, two deformation stages were defined for this area: the first from the Late Eocene to the Early Miocene (approximately 35–21 Ma) and the second from the Pliocene to the present (approximately 5–0 Ma). To contrast the interpretation of that study with petroleum system modeling, the Nunchía-1 pseudo-well was modeled, covering units from 110 Ma (Las Juntas Formation) to the present.

Figure 10

Structural section of the Nunchía Syncline with the location of the Nunchía-1 pseudo-well in the foothill area. Codes: FF-G1-A11-30, FF-G1-28-58 and FF-G1-28-56 correspond with AFT samples taken from [37].

As a result of the thermal model applied for calibration, a current heat flow history of 50 mW/m² was obtained (Figure 11a). Additionally, a vitrinite reflectance (%Ro) of 1.5 and a temperature of 152°C at the final depth were recorded (Figure 11b and c).

Figure 11

Results of calibration of the thermal model for the Nunchía-1 pseudo-well: (a) temperature and heat flow versus depth (m), (b) vitrinite %Ro versus depth (m), and (c) temperature versus depth (m).

The subsidence model for the study area shows sedimentation rates ranging between 172 and 7,312 m and temperatures oscillating between 16 and 160°C. The highest sedimentation rate is observed during the Miocene with the deposition of the Guayabo Formation (Figure 12a and b). The relationship between the burial history, thermal maturity, and transformation rate shows a temperature increase from the Oligocene. From the Miocene, the organic generating facies enter the oil window until the Pliocene when the Fómeque Formation enters the gas window (Figure 12c). In contrast to thermal maturity, transformation rates of 60% for the Gachetá Formation and 90% for the Fómeque Formation are observed, indicating the presence of facies with the capacity to generate HCs in this area (Figure 12d).

Figure 12

Relationships between the (a) burial history, (b) thermal maturity, (c) vitrinite %Ro, and (d) hydrocarbon transformation rate (%) across the Nunchía-1 pseudo-well.

4.2.1 Inverse modeling in HeFTy and QTQt

4.2.1.1 MMVB (De Armas Syncline zone)

Figure 13a and b shows the HeFTy model for the samples from the Umir and Lisama Formations. The models presented a good, combined fit (GOF of 1 and 0.99). The AFTs are short (<13 μm) and describe a unimodal distribution, suggesting a single heating event and a significant residence time in the partial annealing zone (PAZ for apatite, which is between 80 and 120°C), likely causing a partial reset of the samples. The thermal history reconstruction for the Umir Formation began 80 Ma ago with its deposition, followed by a heating event that reached its maximum depth point at 15 Ma, recording temperatures of 150°C. From 15 Ma, a cooling phase is noted with temperature attenuation in the time range from 10 to 5 Ma until a possible cooling event is noted from 4 Ma to the present (Figure 13a). The thermal history reconstruction for the Lisama Formation shows a deposition age beginning 51 Ma ago, consistent with the ranges of ages observed by other authors [61,82]. Subsequently, a continuous subsidence event occurs until 39 Ma, noting its maximum burial point and reaching a temperature of 73°C. From 9 Ma, a cooling phase begins, intensifying from 5 Ma and continuing to the present (Figure 13b).

Figure 13

Thermal history model using (a and b) HeFTy and (c and d) QTQt for the Umir and Lisama Formations, respectively.

Figure 13c and d represents the QTQt model for the same samples, considering three constraints (black outlined rectangles). The first rectangle on the left represents the age and temperature during sample deposition, while the other two on the right represent cooling events related to exhumation pulses mentioned in the literature [80]. The modeling of the Lisama Formation (Figure 13c) indicates a heating process that began approximately 65 Ma ago, reaching its maximum depth at 50 Ma with temperatures up to 98°C. Subsequently, a cooling event is noted, reaching a temperature of 54°C between 60 and 34 Ma. Since then, a very slow heating phase is observed, followed by a considerable cooling rate since 3 Ma. For the thermal history of the Umir Formation sample (Figure 13d) analogical to the previous case, we considered three constraints (“black rectangles”). Before the age of deposition, the thermal history is not very clear. A heating process that started 80 Ma ago reached its maximum depth point at 37 Ma, recording temperatures around 170°C. Then, at 32 Ma, a cooling phase is noted. From this point, the cooling process decelerated significantly between 25 and 2 Ma, keeping the rocks at temperatures between 90 and 95°C. From 2 Ma, the cooling phase accelerated again until the present-day temperature is reached.

4.2.1.2 Eastern Cordillera Basin (Soapaga Fault zone)

Figure 14a and b shows the HeFTy model for Lower Socha and Une Formations. The models show a good, combined fit (GOF of 1 and 0.95). The AFTs are short (13 μm), while the Lower Socha Formation sample shows a bimodal distribution (Figure 14a). The Une Formation sample (Figure 14b) shows a unimodal distribution indicating a possible burial event. The thermal history reconstruction for the Lower Socha Formation indicates a cooling episode from 72 Ma before deposition at ∼53 Ma. From there, the formation is buried, reaching its maximum burial point at 28 Ma, recording temperatures of 95°C near the oil window. From there, a cooling phase continues to the present (Figure 14a). The thermal history reconstruction for the Une Formation suggests a thermal history that began 190 Ma ago with a continuous cooling event, followed by deposition between 112 and 104 Ma and heating from 95 Ma, reaching its maximum burial point at 45 Ma, recording a temperature of 216°C, followed by a cooling phase between 45 and 28 Ma, reaching a temperature of 60°C. From there, the cooling rate decreases until it increases again from 6 Ma to the present (Figure 14b).

Figure 14

Thermal history model using (a and b) HeFTy and (c and d) QTQt for the Lower Socha and Une Formations, respectively.

Figure 14c and d represents the model for the Lower Socha and Une Formations. As in the previous cases, the three black rectangles represent user-imposed conditions. The thermal history for the Lower Socha Formation sample (Figure 14c) suggests an initial subsidence event 56 Ma ago, reaching its maximum burial point at 26 Ma, recording a temperature of 80°C. From approximately 22 Ma, the area enters a cooling phase, possibly associated with a slow exhumation event until the present. The model suggests a rapid cooling event between 170 and 110 Ma before the deposition of the Une Formation (Figure 14d). Subsequently, from 110 to 39 Ma, it reaches its maximum heating point, recording a temperature of 200°C. From 39 to 28 Ma, a cooling phase begins, possibly associated with an exhumation event, reaching a temperature of 50°C in a time range of 28 to 25 Ma. From this point, the inflection is interpreted as a very short pulse of heating or quietude between 50 and 60°C. From 4 Ma, a significant cooling event occurs.

4.2.1.3 Eastern Llanos Basin (Nunchía Syncline)

Figure 15a and b represents the HeFTy model for the samples from the Los Cuervos Formation in the western and eastern zones of the Guaicáramo Fault. The models have a good, combined fit (GOF of 0.97 and 0.99). The AFTs are short (between 12 and 13 μm), suggesting that the formation spent some time in the partial annealing zone. The AFT distribution to the west of the fault (Figure 15a) describes an approximately unimodal distribution. The east of the fault (Figure 15b) describes a bimodal distribution, suggesting the possibility of multiple heating/cooling events. For the western zone, the model shows pre-depositional cooling at 65 Ma, followed by deposition between 61 and 55 Ma, with burial heating reaching its maximum burial point at 36 Ma, recording temperatures close to 104°C. From 32 Ma, a cooling phase is noted until 24 Ma, with a temperature record of 62°C. At 22 Ma, a minor heating phase is noted, suggesting a new minor burial event, until 8 Ma, followed by a cooling phase to the present (Figure 15a). The thermal history of the Los Cuervos Formation in the eastern zone begins with a pre-depositional history where the rock cools between 80 and 56 Ma. From there, a heating stage occurs until 38 Ma, where the maximum heating point is reached with maximum temperature values close to 110°C. From 35 to 28 Ma, rapid cooling occurs, reaching a temperature of 70°C. A heating phase is then observed from 28 to 12 Ma, reaching a temperature of 120°C. From 10 Ma to the present, a cooling phase is observed (Figure 15b).

Figure 15

Thermal history model using (a and b) HeFTy and (c and d) QTQt for the Los Cuervos Formation: samples AM-02 and MP-85 (Mora et al., [35]).

Figure 15c and d represents a model for the Los Cuervos Formation samples in the east and west zones of the Guaicáramo Fault, respectively. The thermal history of the sample located to the west of the fault suggests an initial heating event from 50 to 42 Ma, recording a temperature of 70°C, which decreases slightly between 42 and 40 Ma. From 40 Ma, the heating phase resumes, reaching a temperature of 100°C at 29 Ma. From this point, the area is affected by short periods of heating/cooling until reaching 6 Ma when a rapid cooling phase occurs. The thermal history for the sample located to the east of the fault suggests an initial heating event possibly caused by sediment deposition from 58 Ma, reaching 36 Ma with a temperature of approximately 100°C. From 36 to 26 Ma, a cooling phase is evidenced. From 28 Ma, a new heating phase begins, reaching temperatures of up to 125°C at 16 Ma. From 15 Ma to approximately 10 Ma, a cooling phase occurs, followed by heating of the sample to temperatures between 70 and 90°C from 10 to 6 Ma. Subsequently, from 5 Ma to the present, the sample cools rapidly.

5.1.1 MMVB (De Armas Syncline)

The behavior of the thermal histories on both sides of the La Salina Fault is completely asynchronous. The comparison between the models allows corroborating the occurrence of the three exhumation events described in the study of Sánchez et al. [78]. The first event is recorded at ∼40 Ma, denoting a cooling phase in the basin with subsequent stability to temperature. The second event is recorded between 18 and 10 Ma, and the third event at ∼5 Ma reflects the reactivation of the cooling phase. While the inverse models indicate for the Lisama Formation a maximum heating phase between 48 and 40 Ma with temperatures from 80 to 100°C (Figure 13b and c). At the maximum temperature reached (100°C), the oil window would be reached, which could explain why the Lisama Formation with a thickness of 1,225 m is one of the main stratigraphic reservoirs in the MMVB with a smaller extension compared to the La Paz and Mugrosa Formations [83]. This coincides with the results obtained by Moreno et al. [84], who suggest for the Lisama Formation a residence between 40 and 18 Ma closer to 80°C. Combining vitrinite reflectance data, apatite fission-track, detrital U/Pb in zircon, sedimentary petrography, and thermal modelling, these authors suggest the onset of deformation in the De Armas Syncline during Early Oligocene. The 1D traditional modeling indicates a short cooling process during the Eocene for Esmeralda Formation which could coincide with the non-deposition of upper Esmeraldas reported by Moreno et al. [84], then a burial process occurs between 40 and 18 Ma with temperatures below 80°C. A short cooling event is reached at ∼18 Ma, then between 12 and 5 Ma a burial process reaching maximum temperatures of up to 110°C is observed with a maximum heating phase at 5 Ma (Figure 6b). The 1D traditional model suggests a cooling event for the Miocene Real Formation, which is compatible with the onset of deformation during the Early Miocene reported by Moreno et al. [84]. The temperature values reflected in the inverse models suggest that for that time scale, the Umir Formation was in the final oil phase to the early gas phase (Figure 13a and d), while the deeper units recorded in the basin, such as Paja, Tablazo, and Simití, could be overmature.

5.1.2 Eastern Cordillera Basin (Soapaga Fault zone)

The comparison between the models allows corroborating the occurrence of a first exhumation event to the west of the Soapaga Fault at 40 Ma (Figure 14b and d). This is consistent with the results obtained by Ramirez-Arias et al. [37], who suggest a cooling age in the hanging wall of the Soapaga Fault (Floresta Massif) of 36.1 ± 3.7 Ma (Late Eocene). These authors indicate that this age could be the result of higher heating rates during the burial. To the east of the fault, two exhumation events are denoted, the first at 28 Ma and the second at 4 Ma (Figures 9b and 14a and c). The thermal history of the Une Formation in the basin begins approximately at 100 Ma with a continuous subsidence process until reaching its maximum burial point at 40 Ma, recording temperatures closer to 210°C. This last is consistent with fluid inclusion temperatures for the Une Formation, which indicate that the trapped fluid reaches temperatures greater than 235°C [85]. For the Une Formation, the thermal model reaches a maximum temperature of 160°C [86]. In order to explain this difference in temperature, these authors highlight the role of the regional hydrothermal circulation for increasing these temperatures to values greater than 200°C. The study of Toro et al. [86] indicates that the Albian Une Formation enters the oil windows at 20 Ma. This temperature value suggests that for that geological time scale, the deeper units with generating potential could reach the HC transformation phase. The footwall of the Soapaga Fault is a well-established HC province where Late Cretaceous and Tertiary reservoirs are preserved. The Soapaga Thrust has played a crucial role in regional structural control, influencing the distribution of HCs in the area. It has facilitated the exhumation of earlier kitchen areas into their hanging walls, creating connections between reservoirs and source rocks [87]. According to the vitrinite reflectance value determined by Pedraza-Fracica [88], Early Cretaceous sediments reached a depth of 9,000 m and a temperature of 200°C at maximum burial. Late Cretaceous sediments reached a depth of 7,000 m and 160°C, Paleocene sediments at 4,600 m and 125°C, Eocene sediments at 2,300 m and 88°C, Oligocene sediments at 1,600 m and 52°C, and Miocene sediments at 700 m and 24°C. These estimates are based on theoretical models of geothermal gradients and thermal profiles related to fluid flow in active geothermal systems.

5.1.3 Eastern Llanos Basin (Nunchía Syncline)

For the Llanos foothill Basin, we observed significant differences in terms of exhumation between the hanging-wall and the footwall blocks of the Guaicáramo Fault. These differences have been reported by Ramirez-Arias et al. [37] who suggest Late Miocene exhumation (8.9 ± 2.5 Ma) for the hanging wall of Guaicáramo Fault and Late Miocene to Early Pliocene (4.2 ± 1.8 Ma) for the footwall block, or Nunchía Syncline. Also, Mora et al. [35] detected two different cooling events: (1) Middle Miocene and (2) Oligocene to Early Miocene. The comparison between the thermal models denotes a first exhumation event in the time range of 35–22 Ma (Figure 15a and c) for the Monterralo Anticline located at the hanging wall of the Guaicáramo Fault. Then, a heating process between 22 and 10 Ma is observed for the Monterralo Anticline. From 10 Ma to the present, the cooling rate is increased. The QTQt model behavior to both sides of the Guaicáramo Fault exhibits different patterns. For the eastern zone, corresponding to the Nunchía Syncline area (foothill zone), the model suggests (1) a heating episode between 60 and 35 Ma, reaching temperatures closer to 100°C, (2) a cooling episode from 35 to 25 Ma, (3) heating from 25 to 15 Ma, (4) a phase of cooling from 15 to 10 Ma, (5) a heating episode from 10 to 5 Ma, and (6) a cooling episode from 5 Ma to the present. In contrast, for the western zone (Monterralo Anticline), the thermal history suggests heating between 50 and 42 Ma, from 40 to 6 Ma a long residence above 90°C, then a phase of cooling from 6 Ma to the present. The 1D traditional model reflects from Paleocene to Eocene Formations a long residence at temperatures closer to 70°C, then from Oligocene (34 Ma) to Pliocene, the foothill zone was in a subsidence event due to the deposition of Oligocene and Miocene stratigraphic units (Figure 11b). This heating relationship suggests that while an exhumation event occurred in the hinterland zone, a subsidence event occurred in the foothill zone (Figure 15a and d). From 5 Ma, all models agree on an exhumation phase in both zones. Based on this information, it is considered that the models are complementary. The two almost successive heating episodes from 25 to 15 Ma (reaching 130°C) and from 10 to 5 Ma (reaching 100°C) indicate that during those times, the oil window was reached. This could explain the existence of large deposits of wet gas associated with HCs.