Facies architecture of the fluvial Missão Velha Formation (Late Jurassic–Early Cretaceous), Araripe Basin, Northeast Brazil: paleogeographic and tectonic implications

Abstract Sedimentological analysis of the Missão Velha Formation (Araripe Basin, northeast Brazil) is the aim of this paper through detailed facies analysis, architectural elements, depositional systems and paleocurrent data. The main facies recognized were: (i) coarse-grained conglomeratic sandstones, locally pebbly conglomerates, with abundant silicified fossil trunks and several large-to-medium trough cross-stratifications and predominantly lenticular geometry; (ii) lenticular coarse-to-medium sandstones with some granules, abundant silicified fossil wood, and large-to-medium trough cross-stratifications, cut-and fill features and mud drapes on the foresets of cross-strata, (iii) poorly sorted medium-grained sandstones with sparse pebbles and with horizontal stratification, (iv) fine to very fine silty sandstones, laminated, interlayered with (v) decimetric muddy layers with horizontal lamination and climbing-ripple cross-lamination. Nine architectural elements were recognized: CH: Channels, GB: Gravel bars and bed forms, SB: Sand bars and bedforms, SB (p): sand bedform with planar cross-stratification, OF: Overbank flow, DA: Downstream-accretion macroforms, LS: Laminated sandsheet, LA: Lateral-accretion macroforms and FF: Floodplain fines. The lithofacies types and facies associations were interpreted as having been generated by alluvial systems characterized by (i) high energy perennial braided river systems and (ii) ephemeral river systems. Aeolian sand dunes and sand sheets generated by the reworking of braided alluvial deposits can also occur. The paleocurrent measurements show a main dispersion pattern to S, SE and SW, and another to NE/E. These features imply a paleodrainage flowing into the basins of the Recôncavo-Tucano-Jatobá.

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Characterizing heterogeneity in a glaciofluvial deposit using architectural elements, Limehouse, Ontario, Canada

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2013-0020 ◽

2013 ◽

Vol 50 (9) ◽

pp. 911-929 ◽

Cited By ~ 9

Author(s):

J.M. Slomka ◽

C.H. Eyles

Keyword(s):

Late Quaternary ◽

Coarse Grained ◽

Paleoenvironmental Reconstruction ◽

Braided River ◽

Delta Front ◽

Element Analysis ◽

Alluvial Deposits ◽

Fine Grained ◽

Architectural Elements ◽

Facies Associations

Major hydrocarbon and groundwater reservoirs are commonly hosted within coarse-grained alluvial deposits that contain a high degree of sedimentary heterogeneity. This paper presents a detailed characterization of the sedimentary heterogeneity of fluvial–deltaic deposits using architectural element analysis (AEA). Sedimentological data collected from outcrop faces exposing Late Quaternary glaciofluvial deposits in southern Ontario, Canada, is recorded in 31 sedimentary logs. These logs are used to identify nine different facies types, including gravel facies (Gm, Gp, Gt), sand facies (Sr, Sp, St, Ss), and fine-grained facies (Fl and Fd). Variations in facies associations and geometries are defined by five architectural elements (AEs): sand complex (SC), gravel sheet (GS), fine-grained sheet (FS), gravel foreset body (GFB), and concave fill (CF) elements. The spatial arrangement of bounding surfaces (first- to fifth-order) and AEs allows the classification of six EAs, which, in this study, are defined as the largest-scale architectural subunits that allow for architectural-based mapping over a large area. EAs delineated in this study are sandy braided-river (EA1), delta-front (EA2), gravelly braided-river to delta-top (EA3), delta-front to lacustrine (EA4), braided-river to deltaic (EA5), and sand-dominated fluvial (EA6). AEA is utilized here to capture three levels of heterogeneity, which allow detailed reservoir characterization based on geometric objects and can be readily used for computer-based modelling. Outcrop analogue studies such as this one provide insight to the geometries of more deeply buried coarse-grained deposits that form potential reservoirs and enhance paleoenvironmental reconstruction of subsurface alluvial deposits in Canada and elsewhere.

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Badenian (middle Miocene) continental paleoenvironment in the Novohrad–Nógrád Basin (Central Paratethys): a volcano-sedimentary record from the Páris-patak Valley in Hungary

Földtani Közlöny ◽

10.23928/foldt.kozl.2021.151.2.159 ◽

2021 ◽

Vol 151 (2) ◽

pp. 159

Author(s):

Emese M. Bordy ◽

Orsolya Sztanó

Keyword(s):

Grain Size ◽

Middle Miocene ◽

River System ◽

High Energy ◽

Volcanic Field ◽

Bedload Transport ◽

Coarse Grained ◽

Facies Association ◽

Cross Bedding ◽

Facies Associations

Two levels of volcaniclastics, comprising conglomerates, sandstones and mudstones, are interbedded with upper middle Miocene (upper Badenian) andesite pyroclastics near the Hungarian-Slovakian border in the distal region of the Central Slovakian Neogene Volcanic Field. Based on the field sedimentological investigations, the facies of the volcaniclastics (e.g., lateral and vertical grain size changes, sedimentary structures, textures, clast composition), their geometry and field relationships are documented herein with the aim of reconstructing the depositional environment. The silica-cemented volcaniclastics are mostly andesite clasts with only ~ 5% being granitoid, quarzitic, and tuff clasts as well as charred fossil wood fragments. The coarse-grained facies association includes crudely stratified, tabular or lenticular, clast-supported pebble-cobble conglomerates with erosive basal surfaces, b-axis imbrication, alternating with sets of cross-bedding. The fine-grained facies association comprises cross-bedded pebbly to medium-grained sandstone and lenses of tuffaceous clayey siltstone with rare horizontal lamination and water-escape structures. Rip-up mudstone clasts, with diametre up to 1 m, are present in both facies associations, revealing the co-existence of abandoned silty palaeo-channel plugs. Facies associations are arranged in several 0.5-4-m-thick, fining-upwards successions that likely formed in shallow channels as downstream- to laterally accreting longitudinal bars, extensive gravel sheets and bars that migrated in peak flow during floods. Palaeocurrent indicators (i.e., clast imbrication, direction of planar cross-bedding, orientation of petrified wood logs) show bedload transport by traction currents, initially towards ~S, and later towards ~W. Intermittently debris flows also occurred. Cross-bedded sandstones formed as in-channel transverse bars during medium/low discharge. Variation of grain size shows frequent discharge fluctuations during permanently wet conditions in the late Badenian. The 4-5-m-deep, low-sinuosity channels were part of a high-energy, gravel-bed braided-river system on the south-eastern foothills of the Lysec palaeo-volcano. Here, pyroclastics were reworked and redeposited as volcaniclastics during inter-eruption, high-discharge episodes.

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Characterization of a glacial paleo-outburst flood using high-resolution 3-D seismic data: Bjørnelva River Valley, SW Barents Sea

Journal of Glaciology ◽

10.1017/jog.2020.115 ◽

2021 ◽

pp. 1-17

Author(s):

B. Bellwald ◽

S. Planke ◽

S. Polteau ◽

N. Lebedeva-Ivanova ◽

J.I. Faleide ◽

...

Keyword(s):

Seismic Data ◽

Barents Sea ◽

Ice Sheets ◽

River System ◽

High Energy ◽

River Valley ◽

Coarse Grained ◽

Early Pleistocene ◽

Braided River ◽

River Systems

Abstract Proglacial braided river systems discharge large volumes of meltwater from ice sheets and transport coarse-grained sediments from the glaciated areas to the oceans. Here, we test the hypothesis if high-energy hydrological events can leave distinctive signatures in the sedimentary record of braided river systems. We characterize the morphology and infer a mode of formation of a 25 km long and 1–3 km wide Early Pleistocene incised valley recently imaged in 3-D seismic data in the Hoop area, SW Barents Sea. The fluvial system, named Bjørnelva River Valley, carved 20 m deep channels into Lower Cretaceous bedrock at a glacial paleo-surface and deposited 28 channel bars along a paleo-slope gradient of ~0.64 m km−1. The landform morphologies and position relative to the paleo-surface support that Bjørnelva River Valley was formed in the proglacial domain of the Barents Sea Ice Sheet. Based on valley width and valley depth, we suggest that Bjørnelva River Valley represents a braided river system fed by violent outburst floods from a glacial lake, with estimated outburst discharges of ~160 000 m3 s−1. The morphological configuration of Bjørnelva River Valley can inform geohazard assessments in areas at risk of outburst flooding today and is an analogue for landscapes evolving in areas currently covered by the Greenland and Antarctic ice sheets.

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Episodic Sedimentary Evolution of an Alluvial Fan (Huangshui Catchment, NE Tibetan Plateau)

Quaternary ◽

10.3390/quat1020016 ◽

2018 ◽

Vol 1 (2) ◽

pp. 16 ◽

Cited By ~ 3

Author(s):

Linman Gao ◽

Xianyan Wang ◽

Shuangwen Yi ◽

Jef Vandenberghe ◽

Martin Gibling ◽

...

Keyword(s):

Tibetan Plateau ◽

High Energy ◽

Alluvial Fan ◽

Low Energy ◽

Coarse Grained ◽

Tectonic Activity ◽

Last Interglacial ◽

Climate Conditions ◽

Facies Associations ◽

Semi Arid

Alluvial-fan successions record changes in hydrological processes and environments that may reflect tectonic activity, climate conditions and changes, intrinsic geomorphic changes, or combinations of these factors. Here, we focus on the evolution of a stream-dominated fan in a tectonic depression of the Xining basin of China, laid down under a semi-arid climate in the northeastern Tibetan Plateau (NETP). The fan succession is composed of three facies associations, from bottom to top: (1) matrix to clast-supported, poorly sorted, planar cross-stratified to crudely stratified sheets of coarse-grained sediments; (2) horizontal laminated sand, laminated layers of reddish fine silt and yellow coarse silt with stacked mounds of sand; and (3) clay-rich deposits with incipient paleosols. The succession shows rapid sediment aggradation from high-energy to low-energy alluvial fans and finally to a floodplain. The dating results using optically stimulated luminescence (OSL) method show that a gravelly, high-energy fan was deposited during MIS 6, after which a low-energy fan, mainly composed of sand and silt, was deposited and finally covered by flood loam during the MIS 6–5 transition and the warmer last interglacial. Stacked sand mounds are interpreted from their sediment structure and grain-size distribution as shrub-coppice dunes in low-energy fan deposits. They may be considered as a response to the interaction of alluvial and aeolian processes in a semi-arid environment.

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Stratigraphy and palaeoenvironments of the Red Crag and Norwich Crag formations between Aldeburgh and Sizewell, Suffolk, England

Philosophical Transactions of the Royal Society of London Series B Biological Sciences ◽

10.1098/rstb.1988.0125 ◽

1988 ◽

Vol 322 (1210) ◽

pp. 221-272 ◽

Cited By ~ 25

Keyword(s):

Amino Acid ◽

High Energy ◽

Coarse Grained ◽

Core Material ◽

Stage System ◽

Pollen And Spores ◽

Shallow Marine Sediments ◽

Amino Acid Chronology ◽

Tectonic Origin ◽

Borehole Core

This study uses a variety of criteria to examine short-range correlation within the Crag deposits in order to assess the validity of longer-range correlations within the British Pleistocene stage system. To this end, six rotary cored boreholes spaced at 0.5-1.0 km intervals were drilled along a north-south-aligned traverse between Aldeburgh and Sizewell, Suffolk. These show that the thick Red/Norwich Crag sequence is confined to a deep, sharply bounded basin, which is of probable erosional rather than tectonic origin. The undisturbed borehole core material enabled an assessment of the limits of stratigraphic resolution within these dominantly high-energy, shallow marine sediments to be made. Subdivision of the sequence was done on the basis of lithostratigraphical and biostratigraphical (foraminifera, pollen and spores, dinoflagellate cysts, and molluscs) criteria; chronostratigraphical methods (palaeomagnetism and amino acid chronology) were also applied. The various subdivisions indicated by each of these disciplines were in large part consistent, demonstrating that valid stratigraphic units had been identified. Only amino acid chronology did not indicate any obvious subdivision of the sequence. Three lithostratigraphical units were recognized within the thick Crag sequence. The lowest unit (AS-Lith 1) consists of coarse shelly sands interbedded with thinly laminated muds and fine sands. The middle unit (AS-Lith 2) consists of fine- to coarse-grained shelly sands arranged in two coarsening-upwards cycles. Units AS-Lith 1 and AS-Lith 2 are correlated on a lithostratigraphical basis with the Red Crag Formation of the adjacent Aldeburgh-Orford area to the south and are named the Sizewell Member and the Thorpeness Member respectively. The uppermost unit (AS-Lith 3) comprises fine- to medium-grained, well-sorted sands; it correlates with the Chillesford Sand Member of the Norwich Crag Formation of the adjacent Aldeburgh-Orford area. The Sizewell Member of the Red Crag Formation is normally magnetized and palaeontologically distinctive. The pollen, foraminifera and dinoflagellate assemblages firmly establish it as Pre-Ludhamian in age, and probably equivalent to an interval within the Reuverian C to Praetiglian Stages of the Netherlands. The Thorpeness Member of the Red Crag Formation is less easy to place within the British Pleistocene stage system. It is reverse magnetized, at least in part, and foraminifera assemblages suggest possible correlation with the Ludhamian Stage. No identifiable pollen or dinoflagellate assemblages were obtained. The Chillesford Sand Member of the Norwich Crag Formation is largely unfossiliferous but the borehole material has yielded a single pollen spectrum that suggests correlation with the Bramertonian Stage.

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Microstructural Transitions during Powder Metallurgical Processing of Solute Stabilized Nanostructured Tungsten Alloys

Metals ◽

10.3390/met12010159 ◽

2022 ◽

Vol 12 (1) ◽

pp. 159

Author(s):

Nicholas Olynik ◽

Bin Cheng ◽

David J. Sprouster ◽

Chad M. Parish ◽

Jason R. Trelewicz

Keyword(s):

Extreme Environments ◽

High Energy ◽

Grain Structure ◽

Coarse Grained ◽

Ultrafine Grain ◽

Grain Boundary Engineering ◽

Carbon Impurities ◽

Grain Structures ◽

Metallurgical Processing ◽

Size Population

Exploiting grain boundary engineering in the design of alloys for extreme environments provides a promising pathway for enhancing performance relative to coarse-grained counterparts. Due to its attractive properties as a plasma facing material for fusion devices, tungsten presents an opportunity to exploit this approach in addressing the significant materials challenges imposed by the fusion environment. Here, we employ a ternary alloy design approach for stabilizing W against recrystallization and grain growth while simultaneously enhancing its manufacturability through powder metallurgical processing. Mechanical alloying and grain refinement in W-10 at.% Ti-(10,20) at.% Cr alloys are accomplished through high-energy ball milling with transitions in the microstructure mapped as a function of milling time. We demonstrate the multi-modal nature of the resulting nanocrystalline grain structure and its stability up to 1300 °C with the coarser grain size population correlated to transitions in crystallographic texture that result from the preferred slip systems in BCC W. Field-assisted sintering is employed to consolidate the alloy powders into bulk samples, which, due to the deliberately designed compositional features, are shown to retain ultrafine grain structures despite the presence of minor carbides formed during sintering due to carbon impurities in the ball-milled powders.

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Plio-Quaternary history of the Turkish coastal zone of the Enez-Evros Delta: NE Aegean Sea

Mediterranean Marine Science ◽

10.12681/mms.269 ◽

2001 ◽

Vol 2 (2) ◽

pp. 95 ◽

Cited By ~ 8

Author(s):

B. ALPAR

Keyword(s):

Late Pleistocene ◽

Sand Dunes ◽

Aegean Sea ◽

Interglacial Period ◽

Shelf Area ◽

Sea Level Changes ◽

Seismic Profiles ◽

Alluvial Deposits ◽

History Of ◽

Quaternary History

The Enez-Evros Delta, NE Aegean Sea, is located in one the most important wetlands in the world with its sandy offshore islands, abandoned channel mouths, sand-dunes, shoals, marshlands, saline lagoons and saltpans. It comprises very well developed sedimentary units and a prodelta lying on an older submarine delta. The present day elevations of the middle-late Pleistocene marine terraces indicate a regional tectonic uplift in the area. Due to lack of geophysical and bore hole data and partly due to its strategic position, the structural and stratigraphic features of the submarine extension of the delta are not known in detail. In this paper, Plio-Quaternary history of this delta and its submarine part on the Turkish shelf was explored by using high-resolution shallow reflection seismic profiles. The delta is formed by the alluvial deposits of the Enez-Evros River and shaped by their interaction with the sea. It takes place in front of a large and protected ancient bay which was filled rapidly over millennia. The sediments in the plateau off the river are principally pro-deltaic with muddy areas near the river mouths changing to muddy sand further out. The sea-level changes in Plio-Quaternary were characterised by three different seismic stratigraphic units on the folded Miocene limestone basement. In the late Pleistocene, the shelf area over an Upper Miocene basement was flooded during the Riss-Würm interglacial period, exposed in the Würm glacial stage, and flooded once again during the Holocene transgression.

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Eocene-Oligocene sedimentation in the external areas of the Moldavide Basin (Marginal Folds Nappe, Eastern Carpathians, Romania): sedimentological, paleontological and petrographic approaches

Geologica Carpathica ◽

10.2478/v10096-009-0029-9 ◽

2009 ◽

Vol 60 (5) ◽

pp. 397-417 ◽

Cited By ~ 14

Author(s):

Crina Miclăuş ◽

Francesco Loiacono ◽

Diego Puglisi ◽

Dorin Baciu

Keyword(s):

Source Area ◽

Late Eocene ◽

Low Rank ◽

Coarse Grained ◽

Facies Association ◽

Compositional Uniformity ◽

Eastern Carpathians ◽

Extensional Tectonic ◽

Facies Associations ◽

Depositional Systems

Eocene-Oligocene sedimentation in the external areas of the Moldavide Basin (Marginal Folds Nappe, Eastern Carpathians, Romania): sedimentological, paleontological and petrographic approachesThe Marginal Folds Nappe is one of the most external tectonic units of the Moldavide Nappe System (Eastern Carpathians), formed by Cretaceous to Tertiary flysch and molasse deposits, piled up during the Miocene closure of the East Carpathian Flysch basin, cropping out in several tectonic half-windows, the Bistriţa half-window being one of them. The deposits of this tectonic unit were accumulated in anoxic-oxic-anoxic conditions, in a forebulge depozone (sensuDeCelles & Giles 1996), and consist of a pelitic background sporadically interrupted by coarse-grained events. During the Late Eocene the sedimentation registered a transition from calcareous (Doamna Limestones) to pelitic (Bisericani Beds) grading to Globigerina Marls at the Eocene-Oligocene boundary, and upward during the Oligocene in deposits rich in organic matter (Lower Menilites, Bituminous Marls, Lower and Upper Dysodilic Shales) with coarsegrained interlayers. Seven facies associations were recognized, and interpreted as depositional systems of shallow to deeper water on a ramp-type margin. Two mixed depositional systems of turbidite-like facies association separated by a thick pelitic interval (Bituminous Marls) have been recognized. They were supplied by a "green schists" source area of Central Dobrogea type. The petrography of the sandstone beds shows an excellent compositional uniformity (quartzarenite-like rocks), probably representing a first cycle detritus derived from low rank metamorphic sources, connected with the forebulge relief developed on such a basement. The sedimentation was controlled mainly by different subsidence of blocks created by extensional tectonic affecting the ramp-type margin of the forebulge depozone.

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The late Miocene eolian record at the eastern margin of the Puna Plateau, NW Argentina: Evidence of upper-tropospheric paleocirculation

Journal of Sedimentary Research ◽

10.2110/jsr.2021.018 ◽

2022 ◽

Vol 92 (1) ◽

pp. 32-49

Author(s):

Jonathan Ledesma ◽

Cecilia E. Del Papa ◽

Patricio Payrola

Keyword(s):

Atmospheric Circulation ◽

Late Miocene ◽

Amazon Basin ◽

Coarse Grained ◽

Small Scale ◽

Provenance Analysis ◽

Humid Climate ◽

Upper Troposphere ◽

Facies Associations ◽

Puna Plateau

Abstract The Puna–Altiplano Plateau of the Central Andes is the second-highest plateau in the world (after Tibet), with a mean elevation of 4000 m.a.s.l. and an arid to hyperarid climate. Uplift of the Puna–Altiplano Plateau has affected lower-level atmospheric circulation, acting as a barrier to humid easterly winds from the Amazon basin and favoring an across-strike precipitation gradient resulting in a humid climate towards the east of the plateau and an arid to hyperarid climate in the orogen's interior. In the modern climate, the Bolivian High anticyclone regulates upper troposphere circulation, but little is known about the high-altitude tropospheric circulation of the past. This work focuses on the eolian record of the San Antonio de los Cobres basin along the eastern border of the Puna Plateau, NW Argentina, with the aim of analyzing its origin and thus elucidating the late Miocene winds. The eolian deposits are constrained by 7.8 Ma (K/Ar and U/Pb) and 6.4 Ma (U/Pb) ignimbrites at the nearly basal and upper contacts, respectively. Based on stratigraphic, sedimentological, and provenance analysis of the eolian units, we have identified three main facies associations (FAs): FA1) cross-stratified sandstones with large- to small-scale tabular, planar cross-bedding and with trough cross-stratification; FA2) sandstones with planar to low-angle stratification associated with thinly laminated ripple sandstone strata; FA3) medium- to coarse-grained massive sandstones associated with pebbly to bouldery, matrix-supported conglomerates and clast-supported conglomerates. The lateral and vertical facies assemblages indicate a dune field confined to topographic depressions dominated by transverse dunes with straight and sinuous crestlines that laterally grade into sandsheets associated with ephemeral streams. Paleoflows, lithotypes, and grain-size determinations indicate a persistent north-northwest provenance and wind velocities of 24–38 km/h (with maximum velocities of 55–75 km/h). The results of our analysis coupled with data from previous studies indicates that, for at least the last ca. 8 Myr, the winds have been blowing constantly from the north-northwest with an intensity similar to the present. This implies that the paleo-atmospheric circulation had a similar pattern to the present-day one. Therefore, we conclude that the upper-troposphere circulation in the Puna Plateau of NW Argentina was already regulated by the Bolivian High anticyclone during the Miocene, generating constant north-northwesterly winds.

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Tectonic and geomorphic controls on the lacustrine deposits of the Neogene Vinchina basin, northwestern Argentina

Journal of Sedimentary Research ◽

10.2110/jsr.2020.13 ◽

2020 ◽

Vol 90 (2) ◽

pp. 250-267 ◽

Cited By ~ 1

Author(s):

Sergio A. Marenssi ◽

Carlos O. Limarino ◽

Laura J. Schencman ◽

Patricia L. Ciccioli

Keyword(s):

Water Depth ◽

Drainage Basin ◽

Low Frequency ◽

Sedimentary Facies ◽

Coarse Grained ◽

Lacustrine Deposits ◽

Facies Associations ◽

Order Of Magnitude ◽

Fluvial Sedimentation ◽

The Individual

ABSTRACT Two episodes of lacustrine sedimentation, separated by an erosional surface and fluvial sedimentation, took place in the southern part of the broken foreland Vinchina basin (NW Argentina) between 11 and 5 Ma. The lacustrine deposits, 768 and 740 meters thick, are recorded in the upper part of the Vinchina Formation (“Vinchina lake”) and the lower part of the Toro Formation (“Toro Negro lake”) respectively. According to sedimentological features, four sedimentary facies associations (FAs) are recognized in the lacustrine deposits: 1) thinly laminated mudstones facies association (FA 1), 2) coarsening- and thickening-upward muddy to sandy cycles (FA 2), 3) medium- to coarse-grained sandstones (FA 3), and 4) mudstones, sandstones, and oolitic limestones (FA 4). Altogether, these facies correspond to ephemeral, shallow, lacustrine systems including saline mudflats. The total thickness of each lacustrine interval, the thickness of the individual cycles and their lithology, and the overall aggradational facies arrangement suggest that both lakes developed during underfilled stages of the basin. The coarsening-upward cycles can be regarded as lacustrine parasequences representing cyclic episodes of expansion and contraction of the lake, but unlike marine parasequences these cycles do not correlate to water depth. The development of lacustrine conditions and continuous base-level rise, together with the coeval southward-directed paleoflow indicators, suggest axial drainages and that the basin was externally closed (endorheic) at that time. The large thicknesses of each lacustrine interval also points to high accommodation in the southern part of the Vinchina basin during these times. Lake filling cycles are one order of magnitude thicker than lake depth, so we postulate that subsidence (tectonic) and rise of the spill point (geomorphology) increased accommodation but not water depth. Thus, unlike marine parasequences, the analyzed coarsening-upward cycles do not correlate to water depth, but rather they are controlled by more complex basinal accommodation processes. We hypothesize that the coeval uplift of the Umango and Espinal basement block to the south, coupled with the initial doming of the Sierra de Los Colorados to the east, may have generated the damming of the southward-directed drainage and a zone of maximum accommodation, then controlling the location of the two lakes and the preservation of their thick sedimentary records. Therefore, localized accommodation was enhanced by a combination of tectonic subsidence and topographic growth. The two lacustrine intervals and the intervening fluvial deposits record changing contributions from axial to transverse drainages and different cycles of closed and open conditions in the basin. A low-frequency, closed to open and back to closed (axial to transverse and return to axial drainage) basin evolution, is envisaged by the development of the two lakes (closed stages) and the erosional surface followed by the interval of fluvial sedimentation that separates them (open stage). In addition, several high-frequency lake fluctuations (expansion–contraction) are represented by the coarsening-upward cycles within each lacustrine interval. The thick lacustrine intervals and their intermediate incision surfaces record cyclic filling and re-excavation stages and localized episodes of increased subsidence in the Vinchina basin, which seem to be a common feature of tectonically active broken foreland basins.

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