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X Qiang - One of the best experts on this subject based on the ideXlab platform.
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227-206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic-Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpao-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguao Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin\\\'s oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shao orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 x 1023 to 5 X 1024 N m (equivalent elastic thickness of c. 43-54 km). The orogenic load system initially (c. 227-220 Ma) advanced rapidly (>15 mmyr-1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5mm yr-1 during the sedimentation of the upper two tectonostratigraphic units (c. 220-206 Ma).
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227–206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic–Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpan-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguan Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin's oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shan orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 × 1023 to 5 × 1024 N m (equivalent elastic thickness of c. 43–54 km). The orogenic load system initially (c. 227–220 Ma) advanced rapidly (>15 mm yr−1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5 mm yr−1 during the sedimentation of the upper two tectonostratigraphic units (c. 220–206 Ma).
Philip A Allen - One of the best experts on this subject based on the ideXlab platform.
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the qs problem sediment volumetric balance of proximal Foreland Basin systems
2013Co-Authors: Philip A Allen, John J Armitage, Andrew Carter, Robert A Duller, Nikolas A Michael, Hugh Sinclair, Amy L Whitchurch, Alexander C WhittakerAbstract:Although the stratigraphy of sedimentary Basins depends on the balance between the magnitude and grain-size characteristics of the sediment supply (Qs) and the spatial distribution of tectonic subsidence generating accommodation σ(x), Qs is problematical to measure in present-day sediment routing systems and formidably difficult to predict in their ancient counterparts. This challenge was tackled by treating the sediment discharge from the outlet of mountain catchments as the result of incision by a drainage network with a bulk diffusivity based on the length over which the mean annual rainfall is concentrated. The size, relief and slope of palaeo-catchments acting as feeders for sediment routing systems are used to run simulations of sediment discharge and bulk diffusivity for a range of annual precipitation values. A wide range of observable geological phenomena can be used to converge on the most likely solutions for Qs, including depositional volumes in the Basin, and bedrock thermochronology and detrital cosmogenic nuclide dating to constrain catchment erosion rates. Modelled sediment discharges can be checked with estimates derived from global regressions. The sediment efflux of mountain catchments serves as a boundary condition for down-system sediment transport and deposition. Variations in the volumetric ratio of sediment supply to available accommodation, Qs/σ(x), determines patterns of transverse versus longitudinal (axial) sediment dispersal. The volumetric ratio may change as a result of variations in climatic parameters, tectonic uplift rate and catchment expansion. An abrupt climate change to higher precipitation values promotes higher Qs/σ(x), but transient landscape response causes a return to values close to the baseline, generating a distinctive down-system extension of a gravel ‘spike’. Catchment expansion has a similar, but more prolonged, effect on gravel progradation. In contrast, a change in tectonic forcing, such as an increase in slip rate on a border fault, causes little change in Qs/σ(x), because increased subsidence compensates for the increased sediment supply. Studies of mid Eocene–Oligocene sediment routing systems in the south-central Pyrenees allow the discrimination of different types of proximal wedge-top sedimentary systems on the basis of the volumetric ratio of Qs to accommodation σ(x): (i) small, steep, local fan systems in tectonically ponded, underfilled Basins, supplied by low sediment discharges; (ii) tectonically guided, long-range, axial systems fed by large sediment discharges from widely spaced palaeovalleys; and (iii) large, shallow-sloping transverse megafans burying underlying defunct or active tectonic structures, supplied by high to very high sediment discharges. Understanding the role of variations in Qs helps to explain the syntectonic evolution of proximal Foreland Basin systems. The Oligocene–Miocene North Alpine Foreland Basin, Switzerland, is qualitatively identified as a high-Qs example, the Miocene–Recent northern Apennines of Italy as a low-Qs example and the Eocene-Oligocene southern Pyrenees of Spain as intermediate in character.
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227-206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic-Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpao-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguao Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin\\\'s oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shao orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 x 1023 to 5 X 1024 N m (equivalent elastic thickness of c. 43-54 km). The orogenic load system initially (c. 227-220 Ma) advanced rapidly (>15 mmyr-1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5mm yr-1 during the sedimentation of the upper two tectonostratigraphic units (c. 220-206 Ma).
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227–206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic–Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpan-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguan Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin's oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shan orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 × 1023 to 5 × 1024 N m (equivalent elastic thickness of c. 43–54 km). The orogenic load system initially (c. 227–220 Ma) advanced rapidly (>15 mm yr−1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5 mm yr−1 during the sedimentation of the upper two tectonostratigraphic units (c. 220–206 Ma).
L Yong - One of the best experts on this subject based on the ideXlab platform.
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227-206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic-Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpao-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguao Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin\\\'s oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shao orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 x 1023 to 5 X 1024 N m (equivalent elastic thickness of c. 43-54 km). The orogenic load system initially (c. 227-220 Ma) advanced rapidly (>15 mmyr-1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5mm yr-1 during the sedimentation of the upper two tectonostratigraphic units (c. 220-206 Ma).
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evolution of the longmen shan Foreland Basin western sichuan china during the late triassic indosinian orogeny
2003Co-Authors: L Yong, Philip A Allen, Alexander L Densmore, X QiangAbstract:The Longmen Shan Foreland Basin developed as a flexural foredeep during the Late Triassic Indosinian orogeny, spanning the time period c. 227–206 Ma. The Basin fill can be divided into three tectonostratigraphic units overlying a basal megasequence boundary, and is superimposed on the Palaeozoic–Middle Triassic (Anisian) carbonate-dominated margin of the South China Block. The remains of the load system responsible for flexure of the South China Foreland can be seen in the Songpan-Ganzi Fold Belt and Longmen Shan Thrust Belt. Early in its history the Longmen Shan Foreland Basin extended well beyond its present northwestern boundary along the trace of the Pengguan Fault, to at least the palinspastically restored position of the Beichuan Fault. The basal boundary of the Foreland Basin megasequence is a good candidate for a flexural forebulge unconformity, passing from conformity close to the present trace of the Beichuan Fault to a karstified surface towards the southeast. The overlying tectonostratigraphic unit shows establishment and drowning of a distal margin carbonate ramp and sponge build-up, deepening into offshore marine muds, followed by progradation of marginal marine siliciclastics, collectively reminiscent of the Alpine underfilled trinity of Sinclair (1997). Tectonostratigraphic unit 2 is marked by the severing of the Basin's oceanic connection, a major lake flooding and the gradual establishment of major deltaic-paralic systems that prograded from the eroding Longmen Shan orogen. The third tectonostratigraphic unit is typified by coarse, proximal conglomerates, commonly truncating underlying rocks, which fine upwards into lacustrine shales. The Foreland Basin stratigraphy has been further investigated using a simple analytical model based on the deflection by supracrustal loads of a continuous elastic plate overlying a fluid substratum. Load configurations have been partly informed by field geology and constrained by maximum elevations and topographic profiles of present-day mountain belts. The closest match between model predictions and stratigraphic observations is for a relatively rigid plate with flexural rigidity on the order of 5 × 1023 to 5 × 1024 N m (equivalent elastic thickness of c. 43–54 km). The orogenic load system initially (c. 227–220 Ma) advanced rapidly (>15 mm yr−1) towards the South China Block in the Carnian, associated with the rapid closure of the Songpan-Ganzi ocean, before slowing to < 5 mm yr−1 during the sedimentation of the upper two tectonostratigraphic units (c. 220–206 Ma).
George E Gehrels - One of the best experts on this subject based on the ideXlab platform.
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detrital zircon geochronology of cordilleran retroarc Foreland Basin strata western north america
2013Co-Authors: Andrew K Laskowski, Peter G Decelles, George E GehrelsAbstract:[1] We present a compilation of 8717 U-Pb analyses from 95 detrital zircon samples of Jurassic-Eocene North American Cordillera Foreland Basin strata. Of these samples, 30 are new and previously unpublished. Variation in detrital zircon age spectra between samples records erosion or recycling of basement and cover rocks within the Cordilleran orogenic wedge. Each sample can be classified into one of six major provenance groups, whose age spectra suggest derivation from (1) Mesozoic eolianites of the western United States, (2) Paleozoic passive margin strata of the western United States, (3) Paleozoic passive margin strata of western Canada, (4) the Mogollon Highlands, (5) the Cordilleran magmatic arc, or (6) Yavapai-Mazatzal Province crystalline basement rocks. Referencing these provenance interpretations to their location and stratigraphic deposition age produces a detailed spatial and temporal record of sediment dispersal within the Foreland Basin system. Late Jurassic provenance is dominated by recycling of Mesozoic eolianites from sources in the Sevier thrust belt. Cretaceous-Eocene provenance is dominated by recycling of the passive margin, with increasing complexity upsection. We interpret that this provenance transition records a Basin-wide unroofing sequence. A composite age-probability plot of 1539 young (<250 Ma) detrital zircons reveals at least four age-abundance peaks that we interpret to represent periodic high-flux magmatism in the Cordilleran arc.
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cenozoic Foreland Basin system in the central andes of northwestern argentina implications for andean geodynamics and modes of deformation
2011Co-Authors: Peter G Decelles, Brian K Horton, Barbara Carrapa, George E GehrelsAbstract:[1] Cenozoic strata in the central Andes of northwestern Argentina record the development and migration of a regional Foreland Basin system analogous to the modern Chaco-Parana alluvial plain. Paleocene-lower Eocene fluvial and lacustrine deposits are overlain by middle-upper Eocene hypermature paleosols or an erosional disconformity representing 10–15 Myr. This ‘supersol/disconformity’ zone is traceable over a 200,000 km2 area in the Andean thrust belt, and is overlain by 2–6 km of upward coarsening, eastward thinning, upper Eocene through lower Miocene fluvial and eolian deposits. Middle Miocene-Pliocene fluvial, lacustrine, and alluvial fan deposits occupy local depocenters with contractional growth structures. Paleocurrent and petrographic data demonstrate westerly provenance of quartzolithic and feldspatholithic sediments. Detrital zircon ages from Cenozoic sandstones cluster at 470–491, 522–544, 555–994, and 1024–1096 Ma. Proterozoic-Mesozoic clastic and igneous rocks in the Puna and Cordillera Oriental yield similar age clusters, and served as sources of the zircons in the Cenozoic deposits. Arc-derived zircons become prominent in Oligo-Miocene deposits and provide new chronostratigraphic constraints. Sediment accumulation rate increased from ∼20 m/Myr during Paleocene-Eocene time to 200–600 m/Myr during the middle to late Miocene. The new data suggest that a flexural Foreland Basin formed during Paleocene time and migrated at least 600 km eastward at an unsteady pace dictated by periods of abrupt eastward propagation of the orogenic strain front. Despite differences in deformation style between Bolivia and northwestern Argentina, lithosphere in these two regions flexed similarly in response to eastward encroachment of a comparable orogenic load beginning during late Paleocene time.
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application of Foreland Basin detrital zircon geochronology to the reconstruction of the southern and central appalachian orogen
2010Co-Authors: Hyunmee Park, David L Barbeau, Alan Rickenbaker, Denise Bachmannkrug, George E GehrelsAbstract:Abstract We report the U‐Pb age distribution of detrital zircons collected from central and southern Appalachian Foreland Basin strata, which record changes of sediment provenance in response to the different phases of the Appalachian orogeny. Taconic clastic wedges have predominantly ca. 1080–1180 and ca. 1300–1500 Ma zircons, whereas Acadian clastic wedges contain abundant Paleozoic zircons and minor populations of 550–700 and 1900–2200 Ma zircons consistent with a Gondwanan affinity. Alleghanian clastic wedges contain large populations of ca. 980–1080 Ma and ca. 2700 Ma and older Archean zircons and fewer Paleozoic zircons than occur in the Acadian clastic wedges. The abundance of Paleozoic detrital zircons in Acadian clastic wedges indicates that the Acadian hinterland consisted of recycled material and Taconic‐aged plutons, which provided significant detritus to the Acadian Foreland Basin. The appearance of Pan‐African/Brasiliano‐ and Eburnean/Trans‐Amazonian‐aged zircons in Acadian clastic wedges su...
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detrital zircon geochronology of the eastern magallanes Foreland Basin implications for eocene kinematics of the northern scotia arc and drake passage
2009Co-Authors: David L Barbeau, Eduardo B Olivero, Nicholas L Swansonhysell, Khandaker M Zahid, Kendra E Murray, George E GehrelsAbstract:Abstract U/Pb detrital-zircon geochronology of eleven sandstones collected from Cretaceous through Oligocene strata of the eastern Magallanes Foreland Basin of southernmost Argentina records a dramatic provenance shift near the end of the middle Eocene at ca. 39 Ma. From the Late Cretaceous through most of the middle Eocene, detrital zircons reaching the Foreland Basin were dominantly contributed from ≤ 140 Ma sources, most likely derived from the Patagonian–Fuegian magmatic arc. In contrast, detrital-zircon populations of sampled upper Eocene and Oligocene strata are dominated by 150–190 Ma and pre-Mesozoic grains presumably derived from ignimbrites and granitoids associated with the break-up of Gondwana and from metasedimentary rocks of the Cordillera Darwin metamorphic complex, respectively. Exposures of these units occur in the hinterland of the Fuegian Andes thrust belt and inboard of the Patagonian–Fuegian batholith, suggesting that middle to late Eocene shortening in the rear of the Fuegian orogenic wedge structurally dammed batholith-derived sediment from reaching the Foreland Basin while contributing Jurassic and pre-Mesozoic detritus from hinterland thrust sheets. The timing of this interpreted deformation is in agreement with (1) independent structural, stratigraphic, and thermochronometric evidence of middle Paleogene deformation in the Fuegian Andes, and (2) marine Nd isotope ratio data that reveal initial penetration of Pacific water through the Drake Passage, thereby suggesting a possible link between the kinematics of the Fuegian Andes, the opening of Drake Passage, and if related, the Oi-1 glaciation of Antarctica.
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jurassic onset of Foreland Basin deposition in northwestern montana usa implications for along strike synchroneity of cordilleran orogenic activity
2009Co-Authors: Facundo Fuentes, Peter G Decelles, George E GehrelsAbstract:Stratigraphic, provenance, and subsidence analyses suggest that by the Middle to Late Jurassic a Foreland Basin system was active in northwestern Montana (United States). U-Pb ages of detrital zircons and detrital modes of sandstones indicate provenance from accreted terranes and deformed miogeoclinal rocks to the west. Subsidence commenced ca. 170 Ma and followed a sigmoidal pattern characteristic of Foreland Basin systems. Thin Jurassic deposits of the Ellis Group and Morrison Formation accumulated in a backbulge depozone. A regional unconformity and/or paleosol zone separates the Morrison from Early Cretaceous foredeep deposits of the Kootenai Formation. The model presented here is consistent with regional deformation events registered in hinterland regions, and challenges previous interpretations of a strongly diachronous onset of Cordilleran Foreland Basin deposition from northwestern Montana to southern Canada.
Brian K Horton - One of the best experts on this subject based on the ideXlab platform.
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sediment provenance in contractional orogens the detrital zircon record from modern rivers in the andean fold thrust belt and Foreland Basin of western argentina
2017Co-Authors: Tomas N Capaldi, Brian K Horton, Daniel F Stockli, Ryan N Mckenzie, Margaret OdlumAbstract:Abstract This study analyzes detrital zircon U–Pb age populations from Andean rivers to assess whether active synorogenic sedimentation accurately records proportional contributions from varied bedrock source units across different drainage areas. Samples of modern river sand were collected from west-central Argentina (28–33°S), where the Andes are characterized by active uplift and deposition in diverse contractional provinces, including (1) hinterland, (2) wedge-top, (3) proximal Foreland, and (4) distal broken Foreland Basin settings. Potential controls on sediment provenance were evaluated by comparing river U–Pb age distributions with predicted age spectra generated by a sediment mixing model weighted by relative catchment exposure (outcrop) areas for different source units. Several statistical measures (similarity, likeness, and cross-correlation) are employed to compare how well the area-weighted model predicts modern river age populations. (1) Hinterland Basin provenance is influenced by local relief generated along thrust-bounded ranges and high zircon fertility of exposed crystalline basement. (2) Wedge-top (piggyback) Basin provenance is controlled by variable lithologic durability among thrust-belt bedrock sources and recycled Basin sediments. (3) Proximal Foreland (foredeep) Basin provenance of rivers and fluvial megafans accurately reflect regional bedrock distributions, with limited effects of zircon fertility and lithologic durability in large (>20,000 km 2 ) second-order drainage systems. (4) In distal broken segments of the Foreland Basin, regional provenance signatures from thrust-belt and hinterland areas are diluted by local contributions from Foreland basement-cored uplifts.
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neogene shortening and exhumation of the zagros fold thrust belt and Foreland Basin in the kurdistan region of northern iraq
2017Co-Authors: Renas I Koshnaw, Brian K Horton, Daniel F Stockli, Douglas E Barber, Mazin Y Tamaragha, Jerome KendallAbstract:Abstract The Zagros fold-thrust belt in the Kurdistan region of Iraq encroached southward toward a rapidly subsiding Neogene Foreland Basin and was later partitioned by out-of-sequence shortening focused along the Mountain Front Flexure (MFF), as defined by new low-temperature thermochronologic, stratigraphic, and provenance results. Apatite (U-Th)/He ages document rapid deformation advance from the Main Zagros Fault to southern frontal structures (Kirkuk, Shakal, and Qamar thrusts) at ~ 10–8 Ma, followed by potential basement-involved out-of-sequence development of the MFF (Qaradagh anticline) by ~ 5 Ma. Distinct shifts in detrital zircon U-Pb provenance signatures for Neogene Foreland Basin fill provide evidence for drainage reorganization during fold-thrust belt advance. U-Pb age spectra and petrologic data from the Injana (Upper Fars) Formation indicate derivation from a variety of Eurasian, Pan-African, ophiolitic and Mesozoic-Cenozoic volcanic terranes, whereas the Mukdadiya (Lower Bakhtiari) and Bai-Hasan (Upper Bakhtiari) Formations show nearly exclusive derivation from the Paleogene Walash-Naopurdan volcanic complex near the Iraq-Iran border. Such a sharp cutoff in Eurasian, Pan-African, and ophiolitic sources is likely associated with drainage reorganization and tectonic development of the geomorphic barrier formed by the MFF. As a result of Zagros crustal shortening, thickening and loading, the Neogene Foreland Basin developed and accommodated an abrupt influx of fluvial clastic sediment that contains growth stratal evidence of synkinematic accumulation. The apparent out-of-sequence pattern of upper crustal shortening in the hinterland to Foreland zone of Iraqi Kurdistan suggests that structural inheritance and the effects of synorogenic erosion and accumulation are important factors influencing the irregular and episodic nature of orogenic growth in the Zagros.
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cenozoic sedimentation and exhumation of the Foreland Basin system preserved in the precordillera thrust belt 31 32 s southern central andes argentina
2014Co-Authors: Mariya Levina, Brian K Horton, Facundo Fuentes, Daniel F StockliAbstract:Andean retroarc compression associated with subduction and shallowing of the oceanic Nazca plate resulted in thin-skinned thrusting that partitioned and uplifted Cenozoic Foreland Basin fill in the Precordillera of west-central Argentina. Evolution of the central segment of the Precordillera fold-thrust belt is informed by new analyses of clastic nonmarine deposits now preserved in three intermontane regions between major east directed thrust faults. We focus on uppermost Oligocene-Miocene Basin fill in the axial to frontal Precordillera at 31–32°S along the Rio San Juan (Albarracin and Pachaco sections) and the flank of one of the leading thrust structures (Talacasto section). The three successions record hinterland construction of the Frontal Cordillera, regional arc volcanism, and initial exhumation of Precordillera thrust sheets. Provenance changes recorded by detrital zircon U-Pb age populations suggest that initial shortening in the Frontal Cordillera coincided with an early Miocene shift from eolian to fluvial accumulation in the adjacent Foreland Basin. Upward coarsening of fluvial deposits and increased proportions of Paleozoic clasts reflect cratonward (eastward) advance of deformation into the Precordillera and resultant structural fragmentation of the Foreland Basin into isolated intermontane segments. Apatite (U-Th)/He thermochronometry of Basin fill constrains to 12–9 Ma the most probable age of uplift-induced exhumation and cooling of Precordillera thrust sheets. This apparent pulse of exhumation is evident in each succession, suggestive of rapid, large-scale exhumation by synchronous thrusting above a single decollement linking major structures of the Precordillera.
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cenozoic Foreland Basin system in the central andes of northwestern argentina implications for andean geodynamics and modes of deformation
2011Co-Authors: Peter G Decelles, Brian K Horton, Barbara Carrapa, George E GehrelsAbstract:[1] Cenozoic strata in the central Andes of northwestern Argentina record the development and migration of a regional Foreland Basin system analogous to the modern Chaco-Parana alluvial plain. Paleocene-lower Eocene fluvial and lacustrine deposits are overlain by middle-upper Eocene hypermature paleosols or an erosional disconformity representing 10–15 Myr. This ‘supersol/disconformity’ zone is traceable over a 200,000 km2 area in the Andean thrust belt, and is overlain by 2–6 km of upward coarsening, eastward thinning, upper Eocene through lower Miocene fluvial and eolian deposits. Middle Miocene-Pliocene fluvial, lacustrine, and alluvial fan deposits occupy local depocenters with contractional growth structures. Paleocurrent and petrographic data demonstrate westerly provenance of quartzolithic and feldspatholithic sediments. Detrital zircon ages from Cenozoic sandstones cluster at 470–491, 522–544, 555–994, and 1024–1096 Ma. Proterozoic-Mesozoic clastic and igneous rocks in the Puna and Cordillera Oriental yield similar age clusters, and served as sources of the zircons in the Cenozoic deposits. Arc-derived zircons become prominent in Oligo-Miocene deposits and provide new chronostratigraphic constraints. Sediment accumulation rate increased from ∼20 m/Myr during Paleocene-Eocene time to 200–600 m/Myr during the middle to late Miocene. The new data suggest that a flexural Foreland Basin formed during Paleocene time and migrated at least 600 km eastward at an unsteady pace dictated by periods of abrupt eastward propagation of the orogenic strain front. Despite differences in deformation style between Bolivia and northwestern Argentina, lithosphere in these two regions flexed similarly in response to eastward encroachment of a comparable orogenic load beginning during late Paleocene time.
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evaluating Foreland Basin partitioning in the northern andes using cenozoic fill of the floresta Basin eastern cordillera colombia
2011Co-Authors: Joel E Saylor, Brian K Horton, Junsheng Nie, Jaime Corredor, Andres MoraAbstract:This paper addresses Foreland Basin fragmentation through integrated detrital zircon U–Pb geochronology, sandstone petrography, facies analysis and palaeocurrent measurements from a Mesozoic–Cenozoic clastic succession preserved in the northern Andean retroarc fold-thrust belt. Situated along the axis of the Eastern Cordillera of Colombia, the Floresta Basin first received sediment from the eastern craton (Guyana shield) in the Cretaceous–early Palaeocene and then from the western magmatic arc (Central Cordillera) starting in the mid-Palaeocene. The upper-crustal magmatic arc was replaced by a metamorphic basement source in the middle Eocene. This, in turn, was replaced by an upper-crustal fold-thrust belt source in the late Eocene which persisted until Oligocene truncation of the Cenozoic section by the eastward advancing thrust front. Sedimentary facies analysis indicates minimal changes in depositional environments from shallow marine to low-gradient fluvial and estuarine deposits. These same environments are recorded in coeval strata across the Eastern Cordillera. Throughout the Palaeogene, palaeocurrent and sediment provenance data point to a uniform western or southwestern sediment source. These data show that the Floresta Basin existed as part of a laterally extensive, unbroken Foreland Basin connected with the proximal western (Magdalena Valley) Basin from mid-Paleocene to late Eocene time when it was isolated by uplift of the western flank of the Eastern Cordillera. The Floresta Basin was also connected with the distal eastern (Llanos) Basin from the Cretaceous until its late Oligocene truncation by the advancing thrust front.