Multianalytical provenance analysis of Eastern Ross Sea LGM till sediments (Antarctica): Petrography, geochronology, and thermochronology detrital data

In order to reveal provenance of detrital sediments supplied by West Antarctic Ice Sheet (WAIS), 19 glaciomarine cores of Last Glacial Maximum age were analyzed from Eastern Ross Sea and Sulzberger Bay. Analytical techniques included petrographic analysis of gravel-sized clasts, geochronology (zircon U-Pb: Zrn-UPb) and thermochronology (apatite fission track: AFT) of sand-sized fractions. Petrographic analysis revealed a similarity with the lithologies presently exposed in western Marie Byrd Land (MBL), with major roles played by low-grade metamorphic rocks and granitoids. Furthermore Zrn-UPb and AFT data allowed to identify the ages of formation and cooling of sedimentary source area, consisting of Cambrian-Precambrian basement (i.e., Swanson Formation in western MBL) which underwent at least two episodes of magma intrusion, migmatization and cooling during Devonian-Carboniferous and Cretaceous-Paleocene times. Scarcity of volcanic clasts in the region of Ross Sea along the front of West Antarctica Ice Streams in association with the occurrence of AFT Oligocene-Pliocene dates suggests a localized tectonic exhumation of portions of MBL, as already documented for the opposite side of West Antarctic Rift System in the Transantarctic Mountains. Furthermore, a Zrn-UPb and AFT population of Late Triassic-Jurassic age indicates the presence of unexposed rocks that formed or metamorphosed at that time in the sedimentary source area, which could be identified in McAyeal Ice Stream and Bindschadler Ice Stream catchment areas

Multiple exhumation episodes during the Cenozoic Tibetan Plateau build-up

<Table 1 Apatite fission-track peak-fitting data and the summary of shape analysis Table S1. Summary of the main morphotectonic events across the NE Tibetan Plateau. Table S2. Apatite fission-track analytical data. Table S3. Existed bedrock apatite fission-track data from the studied regions. Table S4. Summary of the paleoelevation results from the Himalayan-Tibetan orogen. The Table of measurement details of AFT data (including Dpar, track length, shape) and Table of Paleocurrent data are also presented in this dataset

Continental accretion and incremental deformation in the thermochronologic evolution of the Lesser Caucasus

Apatite fission-track analysis and thermochronologic statistical modeling of Precambrian\u2013Oligocene plutonic and metamorphic rocks from the Lesser Caucasus resolve two discrete cooling episodes. Cooling occurred during incremental crustal shortening due to obduction and continental accretion along the margins of the northern branch of the Neotethys. (1) The thermochronometric record of a Late Cretaceous (Turonian\u2013Maastrichtian) cooling/exhumation event, coeval to widespread ophiolite obduction, is still present only in a relatively small area of the upper plate of the Amasia-Sevan-Akera (ASA) suture zone, i.e. the suture marking the final closure of the northern Neotethys during the Paleogene. Such area has not been affected by significant later exhumation. (2) Rapid cooling/exhumation occurred in the Early-Middle Miocene in both the lower and upper plates of the ASA suture zone, obscuring previous thermochronologic signatures over most of the study area. Miocene contractional reactivation of the ASA suture zone occurred contemporaneously with the main phase of shortening and exhumation along the Bitlis suture zone marking the closure of the southern branch of the Neotethys and the ensuing Arabia-Eurasia collision. Miocene collisional stress from the Bitlis suture zone was transmitted northward across the Anatolian hinterland, which was left relatively undeformed, and focused along preexisting structural discontinuities such as the eastern Pontides and the ASA suture zone

Thermochronology of the Miocene Arabia-Eurasia collision zone of southeastern Turkey

The Bitlis-Piitiirge collision zone of SE Turkey is the area of maximum indentation along the &gt; 2400-km-long Assyrian-Zagros suture between Arabia and Eurasia. The integration of (1) fission-track analyses on apatites, (ii) (U-Th)/He analyses on zircons, (iii) field observations on stratigraphic and structural relationships, and (iv) preexisting U-Pb and Ar-Ar age determinations on zircons, amphiboles, and micas provides for the first time an overall picture of the thermochronometric evolution of this collisional orogen. The data set points to ubiquitous latest Cretaceous metamorphism of a passive margin sedimentary sequence and its igneous basement not only along the suture zone but across the entire width of the Anatolia-Tauride block north of the suture. During the early Paleogene the basement complex of the Bitlis and Piitiirge massifs along the suture was rapidly exhumed due to extensional tectonics in a back-arc setting and eventually overlain by Eocene shallow-marine sediments. The entire Oligocene is characterized by a rather flat thermochronometric evolution in the Bitlis orogenic wedge, contrary to the widely held belief that this epoch marked the inception of the Arabia-Eurasia collision and was characterized by widespread deformation. Deposition of a thick Oligocene sedimentary succession in the Mu-Hinis basin occurred in a retroarc foreland setting unrelated to continental collision. During the Middle Miocene, the Bitlis-Piitiirge orogenic wedge underwent a significant and discrete phase of rapid growth by both frontal accretion, as shown by cooling/exhumation of the foreland deposits on both sides of the orogenic prism, and underplating, as shown by cooling/exhumation of the central metamorphic core of the orogenic wedge. We conclude that continental collision started in the mid-Miocene, as also shown by coeval thick syntectonic clastic wedges deposited in flexural basins along the Arabian plate northern margin and contractional reactivation of a number of preexisting structures in the European foreland

New detrital petrographic and thermochronologic constraints on the Late Cretaceous-Neogene erosional history of the equatorial margin of Brazil: Implications for the surface evolution of a complex rift margin

The equatorial margin of Brazil is an example of a rift margin with a complex landscape, dominated by an escarpment perpendicular to the continental margin, which testifies to an equally complex rift and post-rift surface and tectonic evolution. This has been the focus of a long debate on the driving mechanism for post-rift tectonics and on the amount of exhumation. This study contributes to this debate with new petrographic and thermochronologic data on 152 samples from three basins, Para-Maranhao, Barreirinhas and Ceara, on the offshore continental platform. Our detrital record goes back to the rift time at ca. 100 Ma ago and outlines three major evolutionary phases of a changing landscape: a rift phase, with the erosion of a moderate rift escarpment, a Late Cretaceous-Palaeogene post-rift phase of major drainage reorganization and significant vertical erosion and a Late Oligocene-to-Recent post-rift phase of moderate vertical erosion and river headwater migration. We estimate that along the equatorial margin of Brazil, over a large onshore area, exhumation since the Late Cretaceous has totalled locally up to 2-2.5 km and since the late Oligocene did not exceed 1 km

The role of slab geometry in the exhumation of cordilleran-type orogens and their forelands: Insights from northern Patagonia

In cordilleran-type orogens, subduction geometry exerts a fundamental control on the tectonic behavior of the overriding plate. An integrated low-temperature, large thermochronological data set is used in this study to investigate the burial and exhumation history of the overriding plate in northern Patagonia (40°–45°S). Thermal inverse modeling allowed us to establish that a ~2.5–4-km-thick section originally overlaid the Jurassic–Lower Cretaceous successions deposited in half-graben systems that are presently exposed in the foreland. Removal of the sedimentary cover started in the late Early Cretaceous. This was coeval with an increase of the convergence rate and a switch to a westward absolute motion of the South American Plate that was accompanied by shallowing of the subducting slab. Unroofing was probably further enhanced by Late Cretaceous to early Paleogene opening of a slab window beneath the overriding plate. Following a tectonically quiescent period, renewed exhumation occurred in the orogen during relatively fast Neogene plate convergence. However, even the highly sensitive apatite (U-Th)/He thermochronometer does not record any coeval cooling in the foreland. The comparison between Late Cretaceous and Neogene exhumation patterns provides clear evidence of the fundamental role played by inter-plate coupling associated with shallow slab configurations in controlling plate-scale deformation. Our results, besides highlighting for the first time how the whole northern Patagonia foreland was affected by an exhumation of several kilometers since the Late Cretaceous, provide unrivalled evidence of the link between deep geodynamic processes affecting the slab and the modes and timing of unroofing of different sectors of the overriding plate.Fil: Genge, Marie C.. Università di Padova; Italia. Centre National de la Recherche Scientifique; Francia. Université de Lille; Francia. Université du Littoral; FranciaFil: Zattin, Massimiliano. Università di Padova; ItaliaFil: Savignano, Elisa. Università di Padova; ItaliaFil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Confluencia; Argentina. Universidad Nacional de Río Negro. Sede Alto Valle. Instituto de Investigaciones en Paleobiología y Geología; Argentina. Universidad Nacional del Comahue; ArgentinaFil: Gautheron, Cécile. Université Paris Sud; Francia. Centre D'etudes de Saclay; Francia. Centre National de la Recherche Scientifique; FranciaFil: Ramos, Victor Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Mazzoli, Stefano. Università degli Studi di Camerino; Itali

Preliminary Integrated Chronostratigraphy of the AND-2A Core, ANDRILL Southern McMurdo Sound Project, Antarctica

We use all available chronostratigraphic constraints – biostratigraphy, magnetostratigraphy, radioisotopic dates, strontium-isotope stratigraphy, and correlation of compositional and physical properties to well-dated global or regional records – to construct a preliminary age model for ANDRILL SMS Project’s AND-2A drillcore (77°45.488’S, 165°16.605’E, 383.57 m water depth). These diverse chronostratigraphic constraints are consistent with each other and are distributed throughout the 1138.54 m-thick section, resulting in a well-constrained age model. The sedimentary succession comprises a thick early and middle Miocene section below 224.82 mbsf and a condensed middle/late Miocene to Recent section above this. The youngest sediments are Brunhes age (<0.781 Ma), as confirmed by a radioisotopic age of 0.691±0.049 Ma at 10.23 mbsf and the occurrence of sediments that have normal magnetic polarity down to ~31.1 mbsf, which is interpreted to be the Brunhes/Matuyama reversal (0.781 Ma). The upper section is punctuated by disconformities resulting from both discontinuous deposition and periods of extensive erosion typical of sedimentary environments at the margin of a dynamic ice sheet. Additional breaks in the section may be due to the influence of tectonic processes. The age model incorporates several major hiatuses but their precise depths are still somewhat uncertain, as there are a large number of erosional surfaces identified within the stratigraphic section. One or more hiatuses, which represent a total 7 to 8 million years of time missing from the sedimentary record, occur between about 50 mbsf and the base of Lithostratigraphic Unit (LSU) 3 at 122.86 mbsf. Similarly, between about 145 mbsf and the base of LSU 4 at 224.82 mbsf, one or more hiatuses occur on which another 2 to 3 million years of the sedimentary record is missing. Support for the presence of these hiatuses comes from a diatom assemblage that constrains the age of the core from 44 to 50 mbsf to 2.06-2.84 Ma, two radioisotopic dates (11.4 Ma) and a Sr‑isotope date (11.7 Ma) that indicate the interval from 127 to 145 mbsf was deposited between 11.4 and 11.7 Ma, and three diatom occurrence datums from between 225.38 and 278.55 mbsf that constrain the age of this upper part of Lithostratigraphic Unit (LSU) 5 to 14.29 - 15.89 Ma. Below the boundary between LSU 5 and 6 sedimentation was relatively continuous and rapid and the age model is well-constrained by 9 diatom datums, seven 40Ar-39Ar dates, one Sr-isotope date, and 19 magnetozones. Even so, short hiatuses (less than a few hundred thousand years) undoubtedly occur but are beyond the resolution of current chronostratigraphic age constraints. Diatom first and last occurrence datums provide particularly good age control from the top of LSU 6 down to 771.5 mbsf (in LSU 10), where the First Occurrence (FO) of Thalassiosira praefraga (18.85 Ma) is observed. The diatom datum ages are supported by radioisotopic dates of 17.30±0.31 Ma at 640.14 mbsf (in LSU 9) and 18.15±0.35 and 17.93±0.40 Ma for samples from 709.15 and 709.18 mbsf (in LSU 10), respectively, and 18.71±0.33 Ma for a sample from 831.67 mbsf (in LSU 11). The sediments from 783.69 mbsf to the base of the hole comprise two thick normal polarity magnetozones that bound a thinner reversed polarity magnetozone (958.59 - 985.64 mbsf). This polarity sequence most likely encompasses Chrons C5En, C5Er, and C6n (18.056 - 19.772 Ma or slightly older given uncertainties in this section of the geomagnetic polarity timescale), but could be also be Chrons C6n, C6r, and C6An.1n (18.748 - 20.213 Ma). Either polarity sequence is compatible with the 40Ar–39Ar age of 20.01±0.35 Ma obtained from single-grain analyses of alkali feldspar from a tephra sample from a depth of 1093.02 mbsf, although the younger interpretation allows a better fit with chronostratigraphic data up-core. Given this age model, the mean sedimentation rate is about 18 cm/k.y. from the top of LSU 6 to the base of the hole.Published221-2202.2. Laboratorio di paleomagnetismoN/A or not JCRreserve

From cylindrical to non‐cylindrical foreland basin: Pliocene–Pleistocene evolution of the Po Plain–Northern Adriatic basin (Italy)

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Reconstrucción de la evolución tectónica del Cerro Domuyo y del extremo norte de la cordillera del viento (36° - 37°s) a partir de la integración de datos geofísicos, estructurales, geocronológicos, y modelos termo-numéricos

El Cerro Domuyo es considerado uno de los centros ígneos del Plio-Pleistoceno más voluminosos de los Andes del Sur, y alberga uno de los campos geotérmicos de alta entalpía más grandes del mundo con una importante actividad actual. Su estructura ha sido caracterizada como un amplio anticlinal, con un eje N-S que inclina suavemente hacia el norte, desarrollado durante la orogenia andina y deformado en el Mioceno medio-Plioceno durante el emplazamiento del Complejo Volcánico Domuyo (CVD) (Llambías et al. 1978). El CVD está compuesto por un stock porfídico de composición granítica-diorítica, interpretado como la sección superior de una cámara magmática Miocena-Pliocena media, fuertemente erosionada y parcialmente expuesta, alimentada a través de un sistema de fracturas preexistentes y complementada por una espesa secuencia de rocas volcánicas y volcaniclásticas (Llambías et al. 1978; Miranda et al. 2006).La integración de un análisis estructural detallado con datos geofísicos preexistentes sugiere que el arreglo estructural del área ha sido controlado por la reactivación de estructuras de basamento (Galetto et al. 2018). La estructura principal inferida a lo largo del flanco occidental del cerro Domuyo es la Falla Manchana Covunco (FMC), caracterizada como una falla normal local, con vergencia occidental y rumbo N-S (Galetto et al. 2018). La FMC es una estructura ciega, cubierta por la secuencia volcánica Plio-Cuaternaria, que ejerce un control de primer orden sobre la dinámica del campo geotérmico de Domuyo (Galetto et al. 2018). Un conjunto de fallas de basamento de orientación ∼E-O la intersecta y controla la ubicación de las principales manifestaciones geotérmicas. El modelado termo-numérico de datos geocronológicos de U-Pb en circones magmáticos, junto con datos de trazas de fisión y (U-Th-Sm)/He en apatitas y circones del flanco occidental del cerro Domuyo, revela dos episodios de enfriamiento rápido durante el Albiano-Campaniano (∼110-75 Ma) y el Eoceno (∼55-35 Ma), que pueden ser vinculados con períodos de exhumación controlados por una tectónica de tipo compresiva (Galetto et al. 2021). El primer evento impulsó el enfriamiento-exhumación del basamento con el levantamiento de un amplio anticlinal de orientación N-S, mientras que el segundo es responsable de la inversión de la FMC y la deformación de la secuencia sedimentaria mesozoica. Nuevos datos termocronológicos provenientes del extremo norte de la Cordillera del Viento sugieren que el patrón de enfriamiento identificado en el área de Domuyo podría tener una impronta regional, extendiéndose en el ámbito de la Faja Plegada y Corrida de Chos Malal.Fil: Galetto, Antonella Tamara. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Estudios Andinos "Don Pablo Groeber". Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Estudios Andinos "Don Pablo Groeber"; ArgentinaFil: Garcia, Victor Hugo. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Zattin, Massimiliano. Università di Padova; ItaliaFil: Georgieva, Victoria. Universidad Austral de Chile; ChileFil: Bechis, Florencia. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio. Universidad Nacional de Río Negro. Instituto de Investigaciones en Diversidad Cultural y Procesos de Cambio; ArgentinaFil: Sobel, Edward R.. Universitat Potsdam; AlemaniaFil: Glodny, Johannes. GFZ German Research Centre for Geosciences; AlemaniaFil: Caselli, Alberto Tomás. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Patagonia Norte. Instituto de Investigación en Paleobiología y Geología; ArgentinaFil: Bordese, Sofia. LA - Te Andes S.A. Laboratorio de Termocronología de Los Andes; ArgentinaFil: Arzadún, Guadalupe. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. LA - Te Andes S.A. Laboratorio de Termocronología de Los Andes; ArgentinaFil: Becchio, Raul Alberto. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaXVIII Reunión de TectónicaSan LuisArgentinaAsociación Geológica ArgentinaUniversidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y NaturalesComisión de Tectónica de la Asociación Geológica Argentin