CENOZOIC BASIN INVERSION AS RECORDED IN THE GIRÓN FORMATION, NORTHERN ANDES OF COLOMBIA

The Yariguíes Anticlinorium, a regional structure located at the western flank of the Eastern Cordillera of Colombia, includes the thickest record of continental sedimentary rocks accumulated near to the Jurassic–Cretaceous boundary. The sedimentary rocks are lithoarenites and feldspathic arenites, grouped in the Girón Formation, and deposited in a Late Jurassic extensional basin interpreted in this work as a rift basin. We analysed the sedimentologic and compositional characteristics of two sections that accumulated in a complex rift system. We identified important thickness variations, from 3350-m in the type section to at least 525-m in a reference section in the Zapatoca area, as well as petrographic and lithofacies changes. This led us to confirm that the Girón Formation encompasses all the continental facies, whose source rock correspond mainly to the exhumed blocks of the Santander Massif during the Late Jurassic. The synrift successions were segmented by transverse structures and regional longitudinal faults of the rift-shoulder, as the Suárez Fault. The tectonic frame of the study area shows the relevance of the W-E compressional regimes, explaining the local kinematics as a heritage of the former configuration and tectonic inversion of the basins. However, clockwise rotation of the stress field was detected from the stress tensor analysis. The latest orientation of the stress tensors and shear joints are related to the effect of the transpressional Bucaramanga and Lebrija faults along the study area.


Introduction
The Jurassic stratigraphy has been a long-debated topic in the Colombian geological all the other similar aged successions, precluding valid regional correlations. However, these differences can also be seen as tools for reconstructing a plausible scenario in which all the data can be conciliated. This has been achieved for some Jurassic basins located in Colombia and Mexico. In the Guajira Peninsula of Colombia, the Jurassic sedimentary rocks of the Cosinas Group have been interpreted as the result of the infilling of one of multiple sub-basins created by Pangea's break-up (Nova et al., 2019). Units with similar characteristics to those of the Girón Formation are reported in Mexico for the Middle Jurassic (e.g. Todos Santos Formation, Huizachal Formation). They are interpreted also as the infilling of extensional basins (Michalzik, 1991;Godínez-Urban et al., 2011) located adjacent to the limit between Laurentia and Gondwana during Pangea's rupture, in the Middle-Late Jurassic (Martini and Ortega-Gutierrez, 2016;Nova et al., 2019). Despite this, only the magmatic evolution of the basins is considered in most North -Andean Jurassic tectonic models (Spikings et al., 2015;Zuluaga et al., 2015;Bustamante et al., 2016;Rodríguez et al., 2018;Zuluaga and López, 2019); therefore, they lack a description of the sedimentary environments and their variations. Other studies try to conciliate all the geological data into different plausible tectonic models but lack a detailed scenario of each of the involved units (e.g. Martini and Ortega-Gutierrez, 2016;Bayona et al., 2020).
We collected stratigraphic, sedimentologic and petrologic data, from two sections located along the same extensional structure, which was one of the multiple sub-basins developed during the Jurassic in the northern part of South America (i.e. Yariguíes Basin sensu Velandia, 2017), located in the current Yariguíes Range. This allows us to describe the basin characteristics and the possible along strike variations in structure and in the source area of the sedimentary rocks.
The geological mapping and measurement of joints and slickensides enable us to carry out an analysis of the structural geology to correlate stress tensors with the tectonic evolution since the initial inversion of the former basin. We also consider necessary to present the I N P R E S S deformational frame along the Yariguíes Anticlinorium, as the regional structure that involves other subordinate folds as the Los Cobardes Anticline.

Tectonics and regional geology
The Colombian Andes are tectonically controlled by the interaction between the oceanic Nazca and Caribbean Plates with the continental South American Plate (Cediel et al., 2003;Cortés et al., 2005), and additionally by the influence of the Chocó-Panamá Block on the western continental margin since the Miocene (Duque-Caro, 1990;Taboada et al., 2000;Montes et al., 2015). Different episodes of subduction and terrane accretion in this border have generated the three mountain chains that compose the Northern Andean Orogen, i.e.
Western Cordillera, Central Cordillera and Eastern Cordillera (Toussaint, 1995;Cooper et al., 1995;Cediel et al., 2003;Cortés et al., 2005). The geometry and composition of the orogen have been controlled, at least since the end of the Cretaceous, by the obliquity between convergent plates and their relative velocity, the allocthony/authocthony of accreted terranes, the reactivation of pre-existent anisotropies and by the buttress effect from the South American Plate and the Amazonian Craton interaction (Boinet et al., 1985;Mora et al., 2013;Jiménez et al., 2014;Mora et al., 2015, Velandia, 2017 Cambrian-Ordovician and Proterozoic metamorphic basement rocks that crop out in some localities associated with regional faults (Gómez-Tapias et al., 2015). Some igneous plutonic bodies of different ages (Paleozoic to Miocene) cut the metamorphic and sedimentary rocks (Mantilla et al., 2011, Leal-Mejía et al., 2019. The general trend of the Eastern Cordillera changes from SW-NE to SE-NW in an inflection area around the El Cocuy Range (Mora et al., 2015, Fig. 1). This inflection is attributed to the inherited structure from previous extensional tectonic phases (Jurassic-Cretaceous rift) and to the buttress effect exerted by the rigid South American Plate against the softer Eastern Cordillera orogen (Rossello et al., 2004;Tesón et al., 2013;Jiménez et al., 2014;. Servitá among other faults are some of these structures (Fig. 1). These faults, although highly debated, seem to have been originated or reactivated from a combined action of rifting and back-arc extension, since Pangea's spreading was starting and the Farallon Plate was subducting beneath the western margin of the South and North American plates (Pindell and Dewey, 1982;Toussaint, 1995;Sarmiento-Rojas et al., 2006;Bayona et al., 2006;Martini andOrtega-Gutierrez, 2016, Bayona et al., 2020 Graben, and the Guatiquía and Pisba grabens for the Cretaceous (Fabre, 1983;Mojica and Kammer, 1995;Cooper et al., 1995, Sarmiento-Rojas et al., 2006Clavijo et al., 2008;Mora et al., 2009;Tesón et al., 2013;Caballero et al., 2013;Velandia, 2017;Bayona et al., 2020). The Yariguíes Basin (Velandia, 2017) was one of the multiple depressions generated during the lithospheric stretching and extension, limited by former normal faults (the I N P R E S S Suárez, Bucaramanga, San Vicente, and La Salina faults) which controlled the distribution of the sedimentary deposits. These faults were part of a rift-shoulder and juxtaposed uplifted basement highs with subsided sub-basins. Some of these rift-shoulder structures were connected with other major faults as the Boyacá, Río Servitá or Soapaga faults, which also controlled the distribution of the accommodation space therefore developing the basins (Kammer and Sánchez, 2006;Velandia, 2017). In posterior thermal subsidence conditions during the Cretaceous, marine sequences were deposited across the maximum extension of the basin (Fabre, 1983;Cooper et al., 1995;Sarmiento-Rojas et al., 2006).
The onset of compressional deformation in the Eastern Cordillera was related to Maastrichtian-Paleocene inversion of former normal faults (the Suárez, Boyacá, and Río Servitá faults), associated to the basin closure and to the Eastern Cordillera orogen generation. An eastern advance of the deformation, with the highest orogenic pulses in the Oligocene, Miocene and Pliocene-Pleistocene is detected with thermochronology (Ross et al., 2009;Caballero et al., 2010;Horton et al., 2010;Parra et al., 2012;Bayona et al., 2013;Caballero et al., 2013;Mora et al., 2013;Mora et al., 2015). This deformation pattern is associated to an episodic accretion of terranes driven by subduction in the western continental border (e.g. Quebradagrande Arc, Arquía Complex, the basement of the Western Cordillera and the Chocó-Panama Block; Duque-Caro, 1990;Villagómez and Spikings, 2013).

Geology of the study area
The Yariguíes Anticlinorium is a divergent folded and faulted structure constituted by  (Julivert, 1958;Royero and Clavijo, 2001) (Fig. 1). The southern termination of the anticlinorium consists of a south-plunging symmetric fold named Los Cobardes Anticline, bounded by reverse faults (Pulido, 1979;Pulido et al., 1986). Besides Los Cobardes Anticline as the main and central structure, the anticlinorium is formed by several minor folds. Towards its western flank the folds are related to the reverse fault system with vergence to the west (Jiménez et al., 2016, Cetina et al., 2019; from this side to the axis of Los Cobardes Anticline other folds are shaped between the El Ramo and El Medio faults. To the eastern flank, the Zapatoca Syncline appears as a conspicuous fold in the hanging wall of the Suárez Fault, along which structural styles are related to thick-skinned tectonics, changing from higher or lower dip angles according to transversal compartmentalization (Flórez and Núñez, 2015). Recent tectonic activity was also reported for the Suárez Fault, mainly from geomorphological observations (Julivert, 1958;Díaz and Suárez, 1998;París et al., 2000;Diederix et al., 2008).
The core of the Yariguíes Anticlinorium is composed of a continental fluvial-alluvial sedimentary succession named Girón Group (sensu Cediel, 1968;Etayo-Serna, 1989) of Late Jurassic-Early Cretaceous age (Pons, 1982). The base of the Girón Group is the Girón Formation (Upper Jurassic) while the Los Santos Formation (Berriasian) constitutes the top (Cediel, 1968;Ward et al., 1973;Etayo-Serna and Rodriguez, 1985). The name Río Lebrija Formation has been proposed by Etayo- Serna (1989) and Clavijo and Camacho (1993) in exchange for the name Girón Formation to avoid the homonymy between the two stratigraphic hierarchies involved (i.e. Girón Group and Girón Formation), and also considering the geographical location of the best preserved and most complete succession on the Lebrija River. Formation (Ward et al., 1973;Royero and Clavijo, 2001) (Figs. 2 and 3), the angular unconformity with the Bocas Formation is faulted (Ward et al., 1973). The overlying Cretaceous marine succession of Valanginian to Maastrichtian age (Sarmiento et al., 2015) crops out in the flanks of the Yariguíes Anticlinorium, and in the core of some inner synclines (Figs. 2 and 3) (Ward et al., 1973;Guzmán, 1985, Cetina et al., 2019. conglomerates (Ward et al., 1973). In the southern central part of the Santander Massif, close to the Río Servitá Fault (Fig. 1), thicknesses of 700m had been reported (Ward et al., 1973). In the Zona de Mesas the Girón Formation has a maximum thickness of 50m and pinches out in an eastward direction until it disappears under the Los Santos Formation Ayala-Calvo et al., 2005), whereas, south of the study area, an upward fining succession of 704m was reported by Pulido (1979). Farther south, in the Floresta Massif ( Fig. 1), the Girón Formation varies in thickness from a few meters to ca. 500m, and develop upward coarsening successions in the proximity of interpreted ancestral normal faults (e.g. Soapaga Fault;Kammer and Sánchez, 2006;Méndez-Espinosa, 2017).
In all these outcrops the Girón Formation rests over different rock types, from Precambrian-Paleozoic metamorphic rocks, Triassic-Jurassic marine marginal siliclastic (Bocas Formation) to volcanoclastic and/or sedimentary rocks (Jordán Formation). After a future detailed stratigraphic study, the above exposed variations in thickness, lithofacies types and vertical profiles may support the usage of the Girón Group nomenclature to encompass the different sections.
The resulting map also took into account some data published in the maps of Royero and Vargas (1999), Diederix et al. (2008), Jiménez et al. (2016) and Cetina et al. (2019).
The stratigraphic analysis was focused on the Girón Formation, with its type locality in the gorge of the Lebrija River. We measured this section using a Jacob staff and considered the stratigraphic descriptions of Cediel (1968) to compare this succession with a stratigraphic section measured and described in the surroundings of Zapatoca (Fig. 2); we used sedimentological criteria by Campbell (1987) and Reineck and Singh (1973) and the facies associations and architectural analysis of Miall (2006).

I N P R E S S
Eleven sandstone samples were taken for petrographic analysis, five from the Zapatoca section and five from the Lebrija River section. One sample was obtained near Lebrija for comparison. A 400 point counting was made in each sample using the Gazzi-Dickinson methodology (Ingersoll et al., 1984), with the criteria given in Table 1.  (1987) and Doblas (1998), especially Riedel and PT-type structures.
The Win-Tensor software (Delvaux and Sperner, 2003) was used for the inversion of stress tensors. It deals with the four parameters defined by Angelier (1994): the three principal stress axes (σ1, σ2 and σ3) and the stress ratio R (σ2-σ3/σ1-σ3). Additionally, R' is also quantified (Delvaux et al., 1997) for consideration of the vertical stress axis: σ1 During processing, Win-Tensor allows the supervision of mechanical, kinematic and quality parameters. In this way, it was possible to separate low confidence data to better constrain the stress tensor. Every subset of data was first filtered until reaching improved counting values: α lower than 30° and the optimisation of function F5. For Delvaux and Sperner (2003) the quality factor for each tensor (QRt) depends mainly on the data amount (n), their level of confidence, and the percentage of used planes based on the total data per site, among others (Sperner and Zweigel, 2010), but in cases of few collected data, it is important to have different orientations of the planes.
Joints were analysed by grouping them according to the location of nearest measurement sites into the structural framework and by plotting data using Stereonet 9.2.3 software to obtain rose and pole diagrams.

Geological mapping
The geology of the northern part of the Yariguíes Anticlinorium is presented in Figure 2 (YR in Fig. 1)  all the folds. From the geological mapping, the Yariguíes Anticlinorium is recognized as the regional structure that involves other minor folds as the La Plazuela, El Ramo and Zapatoca synclines, and the Santa Lucía, Los Cobardes and Coscal anticlines (Fig. 3). The asymmetry of these latter two folds in cross section F-F´ (Fig. 3)

Lebrija Type section
The following description is based on the work of Cediel (1968). The succession of the Girón Formation in the Lebrija River type section has been divided in seven segments (A-G) according to their lithology and facies (Cediel, 1968

I N P R E S S
Segment E is different from the rest of the succession and is composed of fine grained sandstones and grey mudstones in beds no thicker than 70 cm, the sandstone beds have cross-stratification. There are more coal lenses than in the segment B, also there are assymetric ripples, dissecation cracks and root fossils that could indicate the presence of paleosoils (Cediel, 1968). The conglomeratic beds are less frequent than in the other segments.
Segment G represents the top of the succession and is composed of fine-medium grained sandstones, with abscence of interbedded mudstones. The bed thickness decreases upsection from very thick beds (>1 m) at the base to medium-thick beds (10-40 cm) at the top, this segment also shows a fining upward succession. The presence of conglomeratic beds is similar to that in segments A and C, but in this segment they increase up-section.
The main structures present are cross-stratification, tool marks at the base of the sandstones, and asymmetric ripples and desiccation cracks at the top of the succession.
Above this segment, there is continuity in the facies development between the Girón and Los Santos formations (Fig. 4B, C and D) (Cediel, 1968;Clavijo, 1985). which were easily controlled to follow bedding continuity.

Zapatoca Section
The 525 m thick succession of sedimentary rocks described in Zapatoca (Fig. 6) is incomplete because the base of the Girón Formation does not crop out. We infer a thickness of ca. 2 km considering a mean between a reported thickness of 1.2 km in the I N P R E S S southern tip of the anticlinorium (Pulido et al., 1986; although the base does not crop out there either) and 3.35 km reported here for the northern part of the structure (see cross sections E-E´, F-F´ in Fig. 3). The lower 350 m are predominantly sandy and consist of lenticular-bedded pebbly sandstones, interbedded with medium-to fine-grained sandstones (Fig. 6F). Fining-upward successions start with erosive bases, where a pebbly sandstone bed rests over a mudstone package; to the top, sandstone bodies of systematic upward decreasing grain size grade to purple mudstones, which are again cut by conglomeratic sandstones (Figs. 6C and D). Below the base of this 350 m succession, the rocks contain coarser clasts, reaching cobble sizes. Concave-upward cross stratification, trough-cross bedding and normal gradation are the most common structures in the sandstones (Fig. 6E), whereas the mudstones have parallel lamination. Towards the top, the sandstone beds are finer grained and thinner, and become scarce.
Concave-upward stratification is still common in the sandstones. Some isolated sandstone beds include climbing ripples. Green horizons and spots are common in the upper part of the succession, interbedded and affecting the mudstones. The whole succession shows a big fining-upward cycle with subordinated fining-upward successions (Fig. 6).

Petrology
The results of petrographic analysis are listed in Table 1. Five samples were taken from segments A, D and E in the type section of the Girón Formation (Fig. 5), one sample was collected near Lebrija locality that may likely corresponds to segment G, and four samples were collected, distributed along the whole succession of Zapatoca section (Fig. 6), which corresponds to the upper segment of the Girón Formation. The analysed samples of the Zapatoca section plot in the sublitharenite and arkose lithic fields, and the Lebrija River samples are arkose lithic and litharenites, whereas the Lebrija sample plots in the feldspathic litharenite field of the QFR diagram (Folk, 1968) (Fig. 7A). This classification remarks the importance of feldspar-lithic-rich sources. In the provenance QtFL triangle (Dickinson, 1985), one provenance field (recycled orogen) is obtained for the whole set ( Fig. 7B). In the QmFLt discrimination diagram (Dickinson, 1985), three fields (continental transitional, mixed and recycled quartzose) are common for both Zapatoca and Lebrija River samples (Fig. 7C). One Zapatoca sample plots in the dissected arc field and the Lebrija and one Lebrija River sample plot in the recycled transitional field (Fig. 7C).
Althought with dispersion, the LmLvLs diagram (Marsaglia and Ingersoll, 1992) separates some Lebrija River and Zapatoca samples, putting the Lebrija River samples closer to the Lv corner and relating them to a volcanic source, whereas Zapatoca samples plot closer the Ls corner (Fig. 7D). In the QmKP diagram (Dickinson, 1985) almost all the samples are grouped in the field related to the highest compositional maturity with sources in continental blocks (Fig. 7E).

Stress tensor analysis and interpretation
One stress tensor was obtained per each one of the 14 sites considered in this study (Figs. 8 and 9); only 73 of the total 103 measured fault planes were taken into account for the inversion method (71% of the data). The results are summarised in Table 2 and shown in the geological maps of the Lebrija River, Lebrija and Zapatoca sectors (Figs. 8 and 9).
The obtained stress tensors for the Lebrija River (Fig. 8)  also related to the regional stress tensor of the sinistral strike-slip Bucaramanga Fault (Velandia and Bermúdez, 2018;Velandia et al., 2020).
In the Zapatoca sector, several orientations of the stress tensors were obtained, implying that even local differences of the fault planes orientations can be related to changes in the stress field affecting the area (Fig. 9, Table 2). The interpreted latest stress field is related to the kinematics of the Bucaramanga Fault, since the drag of the western block induced a NW-SE tensor, as in sites 9 and 12 ( Fig. 9) under extensional and strike-slip regimes, respectively. Most of the folds and longitudinal reverse faults confirm a NWW-SEE stress tensor, as well as the transverse normal faults trending almost parallel to this tensor ( Fig.   9). Nevertheless, other normal faults trending near S-N are also observed. Such orientation can be associated to interpreted previous NE-SW stress tensors obtained for the other four I N P R E S S sites (sites 10, 11, 13 and 14 in Figure 9), whose stress regimes in strike-slip and extension explain transtensional and/or normal faults. The transverse normal faults are related to strike-slip faults as revealed by the planes projected to the lower hemisphere and stress tensors in beach balls, and even have been reactivated with such components under the NW-SE stress tensor (sites 12 and 9 in Figure 9, Table 2). Differences in the horizontal compressional axes (or Shmax) of this previous stress tensor indicate some clockwise rotation from NE-SW to NEE-SWW, perhaps in accordance with the local kinematics of the structures.  . Tensor and beachball distribution in the Zapatoca area. Angelier (1994) graphics are also plotted for a better fault visualisation. Square, triangle and circle represent σ1, σ2 and σ3, respectively. Legend and conventions as in the geologic map.

Joints
Considering the structural framework of the area and the location of sites with measured joints, it was possible to group data around the Lebrija River and Zapatoca areas. For the first sector, we analysed the data distributed into four areas bounded by faults (Fig. 10A). Meanwhile, data located between the Lebrija and Portugal faults maintain the previous trends of shear but show a W-E orientation as the main set. These transverse joints are also observed westward of the Portugal Fault, but in a tensile pattern with a NNE trend, which is almost parallel to this longitudinal fault.

Joints between the Bucaramanga and El
For the Zapatoca area, we have clustered the data into three areas: (i) between the Zapatoca and Suárez faults, (ii) Betulia and (iii) NW Zapatoca, between the El Ramo and Zapatoca faults (Fig. 10B). The first group shows the N trending longitudinal joints, but with high angles, which are consistent with tensile fractures parallel to the axial plane of the Coscal Anticline, interpreted as a drag fold of the Suárez Fault. This assumption rises since most of the measured joints of the group correspond to the closest site to the fault, whereas the data of the second set (Betulia) show a random distribution, but for the same reason can be representative of the whole fracture frame of the area. In contrast, the third group which includes the highest data population exhibits in a clear way the W-E trend that matches well with the abundant normal faults of the sector, disposed transverse to the reverse longitudinal faults.

Sedimentology and stratigraphy of the Girón Formation
The Girón Formation in the Rio Lebrija type section shows cyclicity in the facies evolution. The first six segments (A-F) show various cycles of deposition in a braided river system (segments A and C) and its floodplain (segments B, D and F); generating different depositional forms as sandy-gravelly bars, channel fill profiles, and levees and crevasse splays in the floodplain. Segment E represents a less energetic environment in which soils developed, probably a swamp as revealed by the presence of root fossils (Cediel, 1968). Figure 10. Distribution of joints measured in the two studied areas. Red dots represent measurement stations. Graphics present both cumulative directional data and pole density.

I N P R E S S
It is worth noting that the contact between the Girón Formation and the overlying Los Santos Formation is controversial. It has been pointed out as discordant by Ward et al. (1973), but detailed studies by Cediel (1968), Clavijo (1985) and Laverde and Clavijo (1985) have recognised this contact as a transitional one. Although the transition extends to almost 20 m, the lithological composition of both units is contrasting which allows the detection of a change from a unit with rocks composed primarily of feldspar and rock fragments (Girón Formation) to another whose quartz content is higher to almost unique (Los Santos Formation). Using this contact as an indicator of the top, a section of the Girón Formation was measured and described along the Zapatoca-Betulia-San Vicente de Chucurí road, in the Alto Tú y Yo (Figs. 2 and 6).
The thickness of 525-m described in the Zapatoca section right under the contact with Los Santos Formation, can be compared with the upper 1,050 m of the Girón Formation in the Lebrija River section (segment G by Cediel (1968) in Figure 5) (Fig. 11). This part of the Lebrija River section exhibits a sandy homogeneous succession with scarce mudstone inter-bedding; its facies architecture has been attributed to the action of braided rivers close to a mountain front (Cediel, 1968). Right on the top of this succession, a thick matrixsupported conglomerate, named previously as the Tambor Formation (Morales et al., 1958 in Ward et al., 1973) and better defined as the Tambor Member by Etayo- Serna (1989), is interpreted as a debris flow deposit related to an alluvial fan (Clavijo, 1985). None of these characteristics were observed in the Zapatoca section. There, based on the facies associations ( Fig. 6) characterized by the presence of fining upward facies sequences with architectural elements such as levees, crevasse splays and channel fill cycles, the succession was interpreted as generated by gravelly-sandy braided rivers in the lower part, which evolve to more sinuous and stable wandering streams up-section. The upward fining sequence in Zapatoca is the result of a progressive retreat of the clastic sources and widening of the valley, as shown by Gawthorpe and Leeder (2000) for extensional basins; in this sort of basins, well defined by bordering faults, high amounts of subsidence contributes to the establishment of axial drainage systems near the fault traces (Blair, 1988;Prosser, 1993) (Fig. 12). In contrast, The Girón Formation in the Lebrija River section reveals different stacking patterns, from retrogradational in the segments from A to E, to progradational and/or aggradational in the segments F to G (Figs. 5 and 11). The observed variations in the facies sequences in the two sections can be interpreted in two ways: (i) a normal fluvial spatial evolution caused by a southward decrease of the gradient or (ii) a spatial variation in environmental characteristics due to geographical barriers. The short distance between the two sections (~50 km) inhibits the first alternative as the more plausible. As a consequence, the presence of geographical barriers such as mountain ranges and/or depressions, which changed the characteristics of the sedimentary conditions along the strike of the basin is proposed as the principal factor controlling the depositional of sediments (e.g. Athmer and Luthi, 2011) (Fig. 12). In this sense, we propose a close proximity of the Lebrija River segment of the basin to the ancestral Bucaramanga Fault, and consider this structure as a dextral strike-slip fault (transtensional) as proposed by Kammer and Sánchez (2006), Velandia (2017), and Kammer et al., (2020).

I N P R E S S
The presence of releasing and restraining bends along the fault will promote the development of both the accommodation space and the source for a constant flow of clastic material (Fig. 12).
Barriers along the course of extensional basins have been observed both on analogue modelling (McClay et al., 2002) and on natural examples (Gawthorpe and Leeder, 2000;Athmer and Luthi, 2011), and are related to accommodation zones, relay ramps and/or transfer fault zones. The presence of along-strike variations in the sedimentary basin conditions could contribute to the heterogeneous character of the Girón Formation; that varies in thickness, composition and facies sequences, depending on the amount of subsidence and the rock type of the source area for each sub-basin, and also on the climate as a clue factor (Cediel, 1968, Ramos et al., 1986Gawthorpe and Leeder, 2000).
Transverse faulting and folding relative to the main regional longitudinal structures is the current expression of those ancient barriers. Transverse structures presented here (e.g. Quebraditas Fault, El Guayabo Fault, La Zarza Fault, Tablazo Fault, among other unnamed faults), and in previous research (e.g. Infantas High, Gómez et al., 2005;Río Negro Syncline, Kammer and Sánchez, 2006;Río Sogamoso Lineament, Ujueta, 2014) constitute some of the testimony of the ancient barriers.
The local nature of every Jurassic succession that crops out in the area, and along the Eastern Cordillera and the Santander Massif, is evident after having recognised the compartmentalised nature of the basin, generating facial and thickness changes along and across its strike (Julivert, 1958;Cediel, 1968;Pulido, 1979;Ward et al., 1973;Pinto et al., 2008) (Figs. 11 and 12). In this sense, the proposal of a type section is not definite because this section does not describe the characteristics of the whole basin, but only the local features of the succession where analysed (Fig. 11).
The Girón Formation is constituted by stratigraphically dissimilar units cropping out along and across the Eastern Cordillera; lateral facies and thickness changes between them would preclude any direct correlation, although characteristics as provenance, age, fossil content and paleosol horizons can be correlated. The described clastic succession near Zapatoca first known as "Girón layers" (Hettner, 1892in Julivert, 1968

Petrology, provenance and basin tectonics
The sedimentary rocks of the Girón Formation display compositions varying from lithic dominant to quartz-feldspar rich, with different provenance (Fig. 7). These variations can be the result of the unroofing of basement blocks, composed by a volcanic-sedimentary I N P R E S S carapace covering a metamorphic succession with some igneous intrusions (Garzanti, 2016). The erosion of these unroofing basement blocks could be responsible of the facies changes observed in the Giron Formación rocks.
The LmLvLs diagram shows a distinction between the Lebrija River and Zapatoca samples of the Girón Formation. There is a closer relationship between Lebrija River and a volcanic source, whereas the source area for Zapatoca sandstones included mainly a sedimentary source. Some basalts of the Jordán Formation are currently cropping out near the Lebrija River (Cediel, 1968;Ward et al., 1973;Ayala-Calvo et al., 2005;Alarcón and Rodríguez, 2019), and were probably exposed to erosion when the Girón Formation was deposited.
Although a vertical evolution was not detected in our samples, the previous scenario is the most plausible due to the presence of several recycled components coming from different sources. Cediel (1968) and Chacón (1981) (Nova et al., 2019); therefore, suggesting similar sources, at least lithologically, and a similar basin configuration in which segmented blocks and basins were exposed to local erosion and deposition regimes (Fig. 12).
Detrital U-Pb zircon data presented by Horton et al. (2010Horton et al. ( , 2015 (Ward et al., 1973;Van der Lelij et al., 2016a;Leal-Mejía et al., 2019) (Fig. 1). In this scenario, these blocks could have been I N P R E S S exhumed for the time of deposition of the Girón Formation, or previously, providing the major part of the sediment (Cediel, 1968).
Sources in southern latitudes (Floresta Massif) could have provided grains, as have been proposed for Jurassic basins at those latitudes (Kammer and Sánchez, 2006;Méndez-Espinosa, 2017). Part of the older grains could have travelled from farther eastern sources in the Amazonian Craton (Guyana Shield in Horton et al., 2010). Nevertheless, a detailed study regarding paleocurrent directions would be necessary to test these hypotheses in the study area, together with a paleomagnetic survey defining the vertical axis rotations and correcting paleocurrent with those rotations.

Structural geology
The regional structural geology of the Yariguíes Range shows the complexity of an anticlinorium as part of the fold and thrust belt, which is crossed not only by longitudinal faults, but transverse minor structures. This makes the area interesting for getting new structural data to refine crustal models, since considering the range as a single fold (Los Cobardes Anticline) for regional cross sections (e.g. Tesón et al., 2013) does not allow to describe the changes in dip angles of the faults, neither the other minor related folds that could define in detail the structural style of the region. The Yariguíes Anticlinorium as presented here offers a chance to redefine the inner and lateral structuration of the Cretaceous? -Cenozoic tectonic inversion of the Jurassic basin.
For discussion of the tectonic implications of the stress tensor results it is necessary to consider that with the exception of one locality, all the collected data in Zapatoca and Lebrija River areas were measured in rocks of the Girón Formation. Limitations of the results can be related to low amount of measured data in some sites, and some stress tensors are probably more associated to local kinematics.
The Shmax oriented NE-SW, can be related to the onset of compressional deformation in the Eastern Cordillera driven by the accretion of the Western Cordillera to the western continental border 75 -70 Ma ago (Bayona et al., 2013;Villagómez and Spikings, 2013;Mora et al., 2015). Although it is considered the oldest stress tensor among the obtained ones in the area Cetina et al., 2019), some works propose the existence I N P R E S S of previous deformational phases in the Eastern Cordillera during the Early and Late Cretaceous, and relate these compressive events to an east directed flat slab subduction (e.g. Guerrero, 2019). The few tensors in the zone show this event in local extensional (S8 in Figure 8 and S13 in Figure 9) and transtensional (S10 in Figure 9) regimes. The orientation of these stress tensors, as well as the transverse faults in the area, can be related to the reactivation of the transverse barriers of the former Jurassic -Cretaceous basin; since the associated transverse structures settle control as zones of anisotropy. Jiménez et al. The stress field seems to have rotated to a W-E orientation, which may have reactivated the former normal longitudinal faults (e.g. Suárez, Zapatoca, and Betulia faults) as reverse and transpressional (S5, S7 in Figure 8, S11 and S14 in Figure 9). This orientation of the stress tensors can be correlated with the post Early Eocene deformational events driven by the accretion of terranes to the western continental border and by the flattening of the subducted plate (e.g. Gómez et al., 2005, Parra et al., 2012Bayona et al., 2013;Guerrero, 2019). Finally, the NW-SE tensor is related to the drag that imposes the transpressional and sinistral kinematics of the Bucaramanga and Lebrija faults (S1, S2, S3, S4 and S6 in Figure 8), as regionally is explained by Velandia et al., (2020), which locally generates compression across the faults oriented perpendicular to this latest tensor.
The NW-SE tensor is described in the western flank of the Yariguíes Anticlinorium (Cetina et al., 2019) and toward the south of the Bucaramanga Fault (Velandia and Bermúdez, 2018), and can be associated to the Oligocene -Pliocene deformational and exhumational events that had been reported with thermochronology (van der Lelij et al., 2016b;Amaya et al., 2017;Velandia, 2017).
Along the Lebrija River, we observe the mechanical correlation of the stress tensors located between the Lebrija and Bucaramanga faults with the joints, which confirm simple shear of both type of kinematic indicators (slickensides and joints) (Figures 8, 9 and 10 is also possible to conclude the same correlation, although some data show local structural conditions.

Geological evolution
The data presented and discussed here allow us to hypothesise about the geological evolution of the region, from the Late Jurassic, the time when the sequence was deposited (Ward et al., 1973;Clavijo, 1985;Laverde and Clavijo, 1985), until the Miocene-Pliocene, the time when the last and major orogenic pulses occurred (Bayona et al., 2013;. During the Late Jurassic, the deposition of the Girón Formation occurred in extensional or transtensional basins with half-graben geometry (Yariguíes Basin as we hypothesize here).

This geometry is assumed by a comparison with the adjacent Middle Magdalena Valley
Basin (i.e. Tablazo-Magdalena Basin during the Cretaceous; Fabre, 1983) as revealed by the thickness variations and by seismic profiles (Rolón, 2004;Guerrero, 2019). The eastern and northeastern bounding faults separated the basin from the Santander Massif, one of the sediment sources. Inside the basin, normal faults had formed parallel and transverse to the basin, creating inner horst blocks that could generate local sediment sources and configured the sedimentary agents (e.g. changing river direction and creating local depocenters) (Figure 12). The Suárez, Zapatoca, El Ramo (N-S faults) and Tablazo, El Guayabo, among other faults (WNW to ESE transverse) correspond to this type of structures. Paleomagnetic data support basin compartmentalization, as different amounts of rotation have been reported for Jurassic rocks in blocks separated by faults (Ayala-Calvo et al., 2005). Farther north of the study area a regional graben structure may have developed, surrounded by the Santander Massif to the east and the San Lucas proto-Range to the west ; this geometry is supported by reported U-Pb ages in zircons of the Girón Formation close the the San Lucas Range (Horton et al., 2015), which reveal provenance ages of 190 -170 Ma age, also found in Jurassic plutonic rocks of the San Lucas Range (188.9 -155.6 Ma; Leal-Mejía et al., 2019;Bayona et al., 2020).
We recognise the Yariguíes Basin ( Figure 12) as part of one of the multiple regional extensional and/or transtensional basins located in the western equatorial part of Pangea (Machiques, Uribante or Cosinas basins, e.g., Sarmiento-Rojas et al., 2006;Nova et al., I N P R E S S 2019), and originated by rift-related extension (Maze, 1984;Martini and Ortega-Gutierrez, 2016;Nova et al., 2019;Bayona et al., 2020). The ancient location and orientation of these basins is uncertain due to probable block translation and rotation (Maze, 1984;Bayona et al., 2006).
After Cretaceous predominantly marine accumulation, some of the normal faults bounding and/or inside the basin, started an inversion process of the former basin during the Paleocene (Julivert, 1958;Julivert, 1970;Mora et al., 2009;Parra et al. 2012;Bayona et al., 2013, Restrepo-Moreno et al., 2019 or since latest Cretaceous (Parra et al., 2012;Caballero et al., 2013;Bayona, 2018), with major pulses at the Eocene, Oligocene-Miocene and finally in the Pliocene-Pleistocene . These orogenic pulses were the consequence of stress fields generated at the western continental border, as different terrains were being accreted and probably the subducting plate was shallowing (Kennan and Pindell, 2009;Guerrero, 2019), which produced an asynchronic and systematic block uplifting from W to E in the nascent Eastern Cordillera. Similar frames have been proposed for other orogenic chains (e.g. Eastern Sierra Madre, Mexico).
The origination and/or reactivation of the deformational structures, is related in the case of the EC, to the clockwise evolving stress tensors , Cetina et al., 2019.

Conclusions
The Yariguíes Anticlinorium is a regional structure between the Eastern Cordillera and the