scholarly journals Detrital zircon U-Pb geochronology of modern Andean rivers in Ecuador: Fingerprinting tectonic provinces and assessing downstream propagation of provenance signals

Geosphere ◽  
2019 ◽  
Vol 15 (6) ◽  
pp. 1943-1957 ◽  
Author(s):  
Lily J. Jackson ◽  
Brian K. Horton ◽  
Cristian Vallejo
Keyword(s):  
Detrital Zircon ◽  
Foreland Basin ◽  
High Elevation ◽  
Tectonic Deformation ◽  
Thrust Belt ◽  
Environmental Signals ◽  
Magmatic Arc ◽  
Metasedimentary Rocks ◽  
Unconsolidated Sands ◽  
Source Regions

Abstract Recognizing detrital contributions from sediment source regions is fundamental to provenance studies of active and ancient orogenic settings. Detrital zircon U-Pb geochronology of unconsolidated sands from modern rivers that have source catchments with contrasting bedrock signatures provides insight into the fidelity of U-Pb age signatures in discriminating tectonic provenance and downstream propagation of environmental signals. We present 1705 new detrital zircon U-Pb ages for 15 samples of unconsolidated river sands from 12 modern rivers over a large spatial extent of Ecuador (∼1°N–5°S and ∼79°–77°W). Results show distinctive U-Pb age distributions with characteristic zircon age populations for various tectonic provinces along the Andean convergent margin, including the forearc, magmatic arc, and internal (hinterland) and external (foreland) segments of the fold-thrust belt. (1) Forearc and magmatic arc (Western Cordillera) river sands are characterized by Neogene–Quaternary age populations from magmatic sources. (2) Rivers in the hinterland (Eastern Cordillera) segment of the Andean fold-thrust belt have substantial populations of Proterozoic and Paleozoic ages, representing upper Paleozoic–Mesozoic sedimentary and metasedimentary rocks of ultimate cratonic origin. (3) River sands in the frontal fold-thrust belt (Subandean Zone to Oriente Basin) show distinctive bimodal Jurassic age populations, a secondary Triassic population, and subordinate Early Cretaceous ages representative of Mesozoic plutonic and metamorphic bedrock. Detrital zircon U-Pb results from a single regional watershed (Rio Pastaza) spanning the magmatic arc to foreland basin show drastic downstream variations, including the downstream loss of magmatic arc and hinterland signatures and abrupt introduction and dominance of selected sources within the fold-thrust belt. Disproportionate contributions from Mesozoic crystalline metamorphic rocks, which form high-elevation, high-relief areas subject to focused precipitation and active tectonic deformation, are likely the product of focused erosion and high volumes of local sediment input from the frontal fold-thrust belt, leading to dilution of upstream signatures from the hinterland and magmatic arc.

scholarly journals Timing and provenance of Paleoproterozoic supracrustal rocks in the central Thelon tectonic zone, Canada: implications for the tectonic evolution of western Laurentia from ca. 2.1 to 1.9 Ga

2021 ◽  
pp. 1-18
Author(s):  
W.J. Davis ◽  
M. Sanborn-Barrie ◽  
R.G. Berman ◽  
S. Pehrsson
Keyword(s):  
Detrital Zircon ◽  
Foreland Basin ◽  
Tectonic Zone ◽  
Zircon Age ◽  
Slave Craton ◽  
Magmatic Arc ◽  
Tectonic Model ◽  
Metasedimentary Rocks ◽  
Clastic Rocks ◽  
Slave Province

Depositional ages and provenance of metasedimentary rocks provide constraints on the architecture of the interface between the Slave and Rae cratons and processes related to the Thelon Orogen. Clastic rocks analysed from the central Thelon tectonic zone are Paleoproterozoic in age and not remnants of the Archean Yellowknife Supergroup (Slave Province), as originally considered. Two assemblages are recognized. An older clastic assemblage deposited after 2.09 Ga contains detrital zircon age modes of 2.3 and 2.17 Ga, with subordinate Neoarchean and Paleoarchean detritus. Its deposition is interpreted to predate Thelon magmatic activity given that (1) it lacks ca. 2.01–1.97 Ga detritus of Thelon magmatic origin, and (2) correlative clastic rocks occur as inclusions in Thelon plutons and contain ca. 2.0 Ga metamorphic monazite. This assemblage is correlative with both the Mary Frances and Rutledge River groups, establishing a >800 km long basin at ca. 2.1 Ga that received detritus from the western Rae and (or) Buffalo Head terrane(s). Separation from the Slave craton at this time is consistent with the absence of any Slave-affinity detritus. A younger assemblage deposited after 1.95 Ga and prior to 1.91 Ga contains mainly 2.02–1.95 Ga detrital zircon, age modes comparable with adjacent Thelon convergent-margin plutonic rocks. The younger assemblage records deposition of the uplifted and eroded Thelon magmatic arc in an intermontane or foreland basin setting during the later stages of post-collisional convergence. These U–Pb zircon data support a tectonic model for western Laurentia that reconciles differences between the Thelon and Taltson magmatic zones involving ca. 2.1 Ga rifting, ca. 2.01–1.97 Ga convergence, followed by <1.95 Ga thrust-driven exhumation.

Sediment provenance in contractional orogens: The detrital zircon record from modern rivers in the Andean fold-thrust belt and foreland basin of western Argentina

2017 ◽  
Vol 479 ◽  
pp. 83-97 ◽  
Author(s):  
Tomas N. Capaldi ◽  
Brian K. Horton ◽  
N. Ryan McKenzie ◽  
Daniel F. Stockli ◽  
Margaret L. Odlum
Keyword(s):  
Detrital Zircon ◽  
Foreland Basin ◽  
Sediment Provenance ◽  
Thrust Belt

scholarly journals Tectonic influence on axial-transverse sediment routing in the Denver Basin

2022 ◽  
Author(s):  
Glenn R. Sharman ◽  
Daniel F. Stockli ◽  
Peter Flaig ◽  
Robert G. Raynolds ◽  
Marieke Dechesne ◽  
...  
Keyword(s):  
Late Cretaceous ◽  
Detrital Zircon ◽  
Foreland Basin ◽  
The Other ◽  
Front Range ◽  
Denver Basin ◽  
Dispersal Patterns ◽  
Magmatic Arc ◽  
Sedimentary Sequences ◽  
Basin Fill

ABSTRACT Detrital zircon U-Pb and (U-Th)/He ages from latest Cretaceous–Eocene strata of the Denver Basin provide novel insights into evolving sediment sourcing, recycling, and dispersal patterns during deposition in an intracontinental foreland basin. In total, 2464 U-Pb and 78 (U-Th)/He analyses of detrital zircons from 21 sandstone samples are presented from outcrop and drill core in the proximal and distal portions of the Denver Basin. Upper Cretaceous samples that predate uplift of the southern Front Range during the Laramide orogeny (Pierre Shale, Fox Hills Sandstone, and Laramie Formation) contain prominent Late Cretaceous (84–77 Ma), Jurassic (169–163 Ma), and Proterozoic (1.69–1.68 Ga) U-Pb ages, along with less abundant Paleozoic through Archean zircon grain ages. These grain ages are consistent with sources in the western U.S. Cordillera, including the Mesozoic Cordilleran magmatic arc and Yavapai-Mazatzal basement, with lesser contributions of Grenville and Appalachian zircon recycled from older sedimentary sequences. Mesozoic zircon (U-Th)/He ages confirm Cordilleran sources and/or recycling from the Sevier orogenic hinterland. Five of the 11 samples from syn-Laramide basin fill (latest Cretaceous–Paleocene D1 Sequence) and all five samples from the overlying Eocene D2 Sequence are dominated by 1.1–1.05 Ga zircon ages that are interpreted to reflect local derivation from the ca. 1.1 Ga Pikes Peak batholith. Corresponding late Mesoproterozoic to early Neoproterozoic zircon (U-Th)/He ages are consistent with local sourcing from the southern Front Range that underwent limited Mesozoic–Cenozoic unroofing. The other six samples from the D1 Sequence yielded detrital zircon U-Pb ages similar to pre-Laramide units, with major U-Pb age peaks at ca. 1.7 and 1.4 Ga but lacking the 1.1 Ga age peak found in the other syn-Laramide samples. One of these samples yielded abundant Mesozoic and Paleozoic (U-Th)/He ages, including prominent Early and Late Cretaceous peaks. We propose that fill of the Denver Basin represents the interplay between locally derived sediment delivered by transverse drainages that emanated from the southern Front Range and a previously unrecognized, possibly extraregional, axial-fluvial system. Transverse alluvial-fluvial fans, preserved in proximal basin fill, record progressive unroofing of southern Front Range basement during D1 and D2 Sequence deposition. Deposits of the upper and lower D1 Sequence across the basin were derived from these fans that emanated from the southern Front Range. However, the finer-grained, middle portion of the D1 Sequence that spans the Cretaceous-Paleogene boundary was deposited by both transverse (proximal basin fill) and axial (distal basin fill) fluvial systems that exhibit contrasting provenance signatures. Although both tectonic and climatic controls likely influenced the stratigraphic development of the Denver Basin, the migration of locally derived fans toward and then away from the thrust front suggests that uplift of the southern Front Range may have peaked at approximately the Cretaceous-Paleogene boundary.

scholarly journals Reconciling Spatial and Temporal Patterns of Cenozoic Shortening, Exhumation, and Subsidence in the Southern Bolivian Andes

2021 ◽  
Vol 9 ◽  
Author(s):  
Nicholas D. Perez ◽  
Ryan B. Anderson ◽  
Brian K. Horton ◽  
Bailey A. Ohlson ◽  
Amanda Z. Calle
Keyword(s):  
Sediment Accumulation ◽  
Foreland Basin ◽  
High Elevation ◽  
Thrust Belt ◽  
Spatial And Temporal Patterns ◽  
Eastern Cordillera ◽  
Sediment Volume ◽  
Bolivian Andes ◽  
Climate Shifts ◽  
Flexural Modeling

The Bolivian Andes are an archetypal convergent margin orogen with a paired fold-thrust belt and foreland basin. Existing chronostratigraphic constraints highlight a discrepancy between unroofing of the Eastern Cordillera and Interandean Zone fold-thrust systems since 40 Ma and the onset of rapid sediment accumulation in the Subandean Chaco foreland after 11 Ma, previously attributed to Miocene climate shifts. New results from magnetostratigraphic, backstripping, erosional volumetric calculations, and flexural modeling efforts are integrated with existing structural and thermochronologic datasets to investigate the linkages between shortening, exhumation, and subsidence. Magnetostratigraphic and backstripping results determine tectonic subsidence in the Chaco foreland basin, which informs flexural models that evaluate topographic load and lithospheric parameters. These models show that Chaco foreland subsidence is consistent with a range of loading scenarios. Eroded volumes from the fold-thrust belt were sufficient to fill the Chaco foreland basin, further supporting the linkage between sediment source and sink. Erosional beveling of the Eastern Cordillera, local intermontane sediment accumulation after 30–25 Ma, and regional development of the high-elevation San Juan del Oro geomorphic surface from 25 to 10 Ma suggest that the western Eastern Cordillera did not store the large sediment volume expected from erosion of the fold-thrust belt, which arrived in the Subandean Zone after 11 Ma. Eocene to middle Miocene foreland basin accumulation was likely focused between the Eastern Cordillera and Interandean Zone, and has been almost completely recycled into the modern Subandean foreland basin. The delay between initial fold-thrust belt exhumation (early Cenozoic) and rapid Subandean subsidence (late Cenozoic) highlights the interplay between protracted shortening, underthrusting, and foreland basin recycling. Only with sufficient crustal shortening, accommodated by eastward advance of the fold-thrust belt and attendant underthrusting of Brazilian Shield lithosphere beneath the Subandes, did the Subandean zone enter proximal foreland basin deposystems after ca. 11 Ma. Prior to the late Miocene, the precursor flexural basin was situated westward and not wide enough to incorporate the distal Subandean Zone. These results highlight the interplay between a range of crustal and surface processes linked to tectonics and Miocene climate shifts on the evolution of the southern Bolivian Andes.

scholarly journals Detrital zircon provenance record of the Zagros mountain building from the Neotethys obduction to the Arabia-Eurasia collision, NW Zagros fold-thrust belt, Kurdistan region of Iraq

2021 ◽  
Author(s):  
Renas I. Koshnaw ◽  
Fritz Schlunegger ◽  
Daniel F. Stockli
Keyword(s):  
Detrital Zircon ◽  
Upper Cretaceous ◽  
Foreland Basin ◽  
Source Area ◽  
Late Eocene ◽  
Thrust Belt ◽  
Kurdistan Region ◽  
Angular Unconformity ◽  
Tectonic Processes ◽  
Provenance Data

Abstract. Recognition of new angular unconformity and synthesizing of new detrital zircon U-Pb and (U-Th)/He provenance records, including zircon (U-Th)/(He-Pb) double dating, from the NW Zagros elucidate the basin dynamics of the foreland wedge-top and intermontane units, as well as the tectonic processes in the source terranes in response to different geodynamic phases. In this contribution, we present field observations and detrital zircon provenance data from hinterland basins to reconstruct the basin dynamics and the underlying tectonic controls in the NW Zagros in the Kurdistan region of Iraq. Results reveal that the deposition of the suture zone units of the Red Beds Series (RBS; Suwais Group, Govanda Formation, Merga Group) occurred in an intermontane basin on top of folded Upper Cretaceous units with an angular unconformity. The RBS provenance data point at the Paleogene Walash-Naopurdan-Kamyaran (WNK) arc-related complex as a source area and show substantial decrease of magmatism by ~ 36 Ma, as reflected by the youngest ages peaks. New detrital zircon provenance data from the hinterland wedge-top units of the proto-Zagros foreland basin (the Tanjero, Kolosh, and Gercus Formations) exhibit exclusive derivation from the Upper Cretaceous Neotethys ophiolitic terranes, different from the provenance of the older Lower Cretaceous and Paleozoic units that are dominated by the Paleozoic and Neoproterozoic age spectra. These shifts in provenance between different tectonostratigraphic units argue for sediment route reversal from E to W in response to ophiolite obduction, arrival of the WNK complex and commencement of the continental collision during the late Eocene, followed by deposition of the RBS in the hinterland of the proto-Zagros fold-thrust belt, and paleodrainage connection with the post-collisional Neogene foreland basin.

scholarly journals Revised Timing of Cenozoic Atlantic Incursions and Changing Hinterland Sediment Sources during Southern Patagonian Orogenesis

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
pp. 1-18 ◽  
Author(s):  
Julie C. Fosdick ◽  
R. A. VanderLeest ◽  
J. E. Bostelmann ◽  
J. S. Leonard ◽  
R. Ugalde ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Atlantic Coast ◽  
Foreland Basin ◽  
Late Eocene ◽  
Coarse Grained ◽  
Plate Convergence ◽  
Metasedimentary Rocks ◽  
Sediment Routing ◽  
Thrust Sheets ◽  
Major Shift

Abstract New detrital zircon U-Pb geochronology data from the Cenozoic Magallanes-Austral Basin in Argentina and Chile ~51° S establish a revised chronostratigraphy of Paleocene-Miocene foreland synorogenic strata and document the rise and subsequent isolation of hinterland sources in the Patagonian Andes from the continental margin. The upsection loss of zircons derived from the hinterland Paleozoic and Late Jurassic sources between ca. 60 and 44 Ma documents a major shift in sediment routing due to Paleogene orogenesis in the greater Patagonian-Fuegian Andes. Changes in the proportion of grains from hinterland thrust sheets, comprised of Jurassic volcanics and Paleozoic metasedimentary rocks, provide a trackable signal of long-term shifts in orogenic drainage divide and topographic isolation due to widening of the retroarc fold-thrust belt. The youngest detrital zircon U-Pb ages confirm timing of Maastrichtian-Eocene strata but require substantial age revisions for part of the overlying Cenozoic basinfill during the late Eocene and Oligocene. The upper Río Turbio Formation, previously mapped as middle to late Eocene in the published literature, records a newly recognized latest Eocene-Oligocene (37-27 Ma) marine incursion along the basin margin. We suggest that these deposits could be genetically linked to the distally placed units along the Atlantic coast, including the El Huemul Formation and the younger San Julián Formation, via an eastward deepening within the foreland basin system that culminated in a basin-wide Oligocene marine incursion in the Southern Andes. The overlying Río Guillermo Formation records onset of tectonically generated coarse-grained detritus ca. 24.3 Ma and a transition to the first fully nonmarine conditions on the proximal Patagonian platform since Late Cretaceous time, perhaps signaling a Cordilleran-scale upper plate response to increased plate convergence and tectonic plate reorganization.

The middle Cretaceous (110−94 Ma) evolution of Tangza Basin in the western Tibetan Plateau and implications for initial topographic growth of northern Lhasa

2020 ◽  
Author(s):  
Xu Han ◽  
Jin-Gen Dai ◽  
Jie Lin ◽  
Shi-Ying Xu ◽  
Bo-Rong Liu ◽  
...  
Keyword(s):  
Tibetan Plateau ◽  
Early Cretaceous ◽  
Volcanic Rocks ◽  
Foreland Basin ◽  
High Elevation ◽  
Alluvial Fan ◽  
Magmatic Arc ◽  
Clastic Rocks ◽  
Western Tibetan Plateau ◽  
Spinel Composition

Reconstruction of Cretaceous geological evolution of Tibetan Plateau growth is critical for assessing the effect of India-Asia collision on the formation of its high elevation. However, Cretaceous topographic evolution and geodynamic mechanism in northern Lhasa remain ambiguous. Here we present results from sedimentology, zircon U-Pb ages, and detrital Cr-spinel composition of the Tangza Formation in the western part of northern Lhasa. Sedimentary lithofacies document that orbitolinid foraminifera−limestone beds were deposited in a shallow-marine setting, while clastic rocks accumulated in an alluvial fan during the middle Cretaceous. Zircon U-Pb ages of interbedded volcanic rocks place a robust constraint on the initiation of clastic rock deposition at ca. 106 Ma. Sandstones are enriched lithic fragments with abundant volcanic grains. U-Pb ages of detrital zircon display a prominent age population at 101−130 Ma with a 120 Ma peak. These data indicate that the clastic rocks were mainly derived from northern Lhasa, including an Early Cretaceous magmatic arc. Sedimentary and provenance characteristics are most consistent with deposition in a local foreland basin. The activation of south-vergent local thrusting may be responsible for loading of the Tangza foreland basin. This thrust faulting may be associated with crustal shortening induced by the continuous convergence of Lhasa and Qiangtang since collision initiated during the Early Cretaceous. The initial uplift of western and central parts of northern Lhasa and eastern Gangdese arc occurred at ca. 106 Ma, while the widespread uplift of northern and central Lhasa probably initiated at ca. 92 Ma. The mid−Late Cretaceous uplift in Lhasa was significantly earlier than the early Cenozoic India-Asia collision.

scholarly journals Zircon (U-Th)/(He-Pb) double-dating constraints on the interplay between thrust deformation and foreland basin architecture, Sevier foreland basin, Utah

Geosphere ◽  
2021 ◽  
Author(s):  
E.J. Pujols ◽  
D.F. Stockli
Keyword(s):  
Foreland Basin ◽  
Sediment Supply ◽  
Sediment Provenance ◽  
Thrust Belt ◽  
Lower Paleozoic ◽  
Magmatic Arc ◽  
Book Cliffs ◽  
Time Estimates ◽  
Stratal Architecture ◽  
Cordilleran Foreland

The Cretaceous Cordilleran foreland basin strata exposed in the Book Cliffs of eastern Utah and western Colorado have motivated important concepts linking thrust belt deformation and foreland basin evolution largely on the basis of sequence stratigraphy, stratal architecture, and sediment provenance evolution. However, these methods and approaches generally cannot provide critical insights into the temporal or causal linkages between foreland basin architecture and thrust belt deformation. This is in part due to discrepancies in age resolution and lack of evidence with which to directly couple sediment supply and basin-fill evolution to thrust belt unroofing. New detrital zircon (DZ) geothermochronometric data from Upper Cretaceous proximal to distal foreland basin strata in the Book Cliffs provide new quantitative insights into sediment origin and dispersal in relation to thrust belt deformation and exhu­mation. Detailed DZ U-Pb and (U-Th)/He double dating reveals that the Book Cliffs foredeep detritus was mainly delivered by transverse routing systems from two major sources: (1) Neoproterozoic and Lower Paleozoic strata from the central Utah Sevier thrust belt, and (2) Permian–Jurassic and synorogenic Cretaceous strata recycled from the frontal part of the thrust belt. A dramatic increase in Sierran magmatic arc and Yavapai-Mazatzal DZ U-Pb ages, as well as Paleozoic DZ He ages, in the deeper marine portions of the foreland basin points to axial fluvial and littoral sediment input from the Sierran magmatic arc and Mogollon highland sources. Both transverse and axial transport sys­tems acted contemporaneously during eastward propagation of the Late Cretaceous thrust belt. DZ He depositional lag time estimates reveal three distinct exhumation pulses in the Sevier thrust belt in the Cenomanian and Campanian. The exhumation pulses correlate with shifts in sediment prove­nance, dispersal style, and progradation rates in the foreland basin. These new data support conceptual models that temporally and causally link accelerated exhumation and unroofing in the thrust belt to increases in sediment supply and rapid clastic progradation in the foreland basin.

scholarly journals Mesoproterozoic−Early Cretaceous provenance and paleogeographic evolution of the Northern Rocky Mountains: Insights from the detrital zircon record of the Bridger Range, Montana, USA

2020 ◽  
Author(s):  
Chance B. Ronemus ◽  
Devon A. Orme ◽  
Saré Campbell ◽  
Sophie R. Black ◽  
John Cook
Keyword(s):  
Early Cretaceous ◽  
Detrital Zircon ◽  
Foreland Basin ◽  
Mountain Range ◽  
Thrust Belt ◽  
Sediment Sources ◽  
Middle Cambrian ◽  
Sediment Dispersal ◽  
Northern Rocky Mountains ◽  
Basin System

The Bridger Range of southwest Montana, USA, preserves one of the most temporally extensive sedimentary sections in North America, with strata ranging from Mesoproterozoic to Cretaceous in age. This study presents new detrital zircon geochronologic data from eight samples collected across this mountain range. Multidimensional scaling and non-negative matrix factorization statistical analyses are used to quantitatively unmix potential sediment sources from these and 54 samples compiled from previous studies on regional correlative strata. We interpret these sources based on reference data from preserved strata with detrital zircon signatures likely representative of ancient sediment sources. We link these sources to their sinks along sediment dispersal pathways interpreted using available paleogeographic constraints. Our results show that Mesoproterozoic strata in southwest Montana contain detritus derived from the nearby craton exposed along the southern margin of the fault-bounded Helena Embayment. Middle Cambrian strata were dominated by the recycling of local sources eroded during the development of the Great Unconformity. In Devonian−Pennsylvanian time, provenance in southwest Montana shifted to more distal sources along the northeastern to southeastern margins of Laurentia, but more western basins received detritus from outboard sources along a tectonically complicated margin. By the Late Jurassic, provenance in the developing retroarc foreland basin system was dominated by Cordilleran magmatic arcs and fold-thrust belt sources to the west. Eastward propagation of the fold-thrust belt caused recycling of Paleozoic and Jurassic detritus into the foreland basin to dominate by the Early Cretaceous.

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