TY - JOUR A1 - Terbishalieva, Baiansuluu A1 - Timmerman, Martin Jan A1 - Mikolaichuk, Alexander A1 - Altenberger, Uwe A1 - Slama, Jiri A1 - Schleicher, Anja Maria A1 - Sudo, Masafumi A1 - Sobel, Edward A1 - Cichy, Sarah Bettina T1 - Calc-alkaline volcanic rocks and zircon ages of the late Tonian BT - Early Cryogenian arc-related Big Naryn Complex in the Eastern Djetim-Too Range, Middle Tianshan block, Kyrgyzstan JF - International journal of earth sciences N2 - The Big Naryn Complex (BNC) in the East Djetim-Too Range of the Kyrgyz Middle Tianshan block is a tectonized, at least 2 km thick sequence of predominantly felsic to intermediate volcanic rocks intruded by porphyric rhyolite sills. It overlies a basement of metamorphic rocks and is overlain by late Neoproterozoic Djetim-Too Formation sediments; these also occur as tectonic intercalations in the BNC. The up to ca. 1100 m thick Lower Member is composed of predominantly rhyolites-to-dacites and minor basalts, while the at least 900 m thick pyroclastic Upper Member is dominated by rhyolitic-to-dacitic ignimbrites. Porphyric rhyolite sills are concentrated at the top of the Lower Member. A Lower Member rhyolite and a sill sample have LA-ICP-MS U-Pb zircon crystallization ages of 726.1 +/- 2.2 Ma and 720.3 +/- 6.5 Ma, respectively, showing that most of the magmatism occurred within a short time span in the late Tonian-early Cryogenian. Inherited zircons in the sill sample have Neoarchean (2.63, 2.64 Ga), Paleo- (2.33-1.81 Ga), Meso- (1.55 Ga), and Neoproterozoic (ca. 815 Ma) ages, and were derived from a heterogeneous Kuilyu Complex basement. A 1751 +/- 7 Ma Ar-40/Ar-39 age for amphibole from metagabbro is the age of cooling subsequent to Paleoproterozoic metamorphism of the Kuilyu Complex. The large amount of pyroclastic rocks, and their major and trace element compositions, the presence of Neoarchean to Neoproterozoic inherited zircons and a depositional basement of metamorphic rocks point to formation of the BNC in a continental magmatic arc setting. KW - Tianshan orogenic belt KW - Big Naryn complex KW - Tonian–Cryogenian KW - magmatic arc KW - calc-alkaline KW - Kuilyu complex Y1 - 2021 U6 - https://doi.org/10.1007/s00531-020-01956-z SN - 1437-3254 SN - 1437-3262 VL - 110 IS - 1 SP - 353 EP - 375 PB - Springer CY - New York ER - TY - JOUR A1 - Altenberger, Uwe A1 - Cisterna, Clara A1 - Günter, Christina A1 - Gutiérrez, Adolfo Antonio A1 - Rosales, J. T1 - Tectono-metamorphic evolution of the proto-Andean margin of Gondwana BT - Evidence of internal high-grade metamorphism along the northern portion of the Famatinian orogen, Sierra de Aconquija, Sierras Pampeanas Orientales, Argentina JF - Journal of South American earth sciences N2 - The present work gives a detailed analysis of the metamorphic and structural evolution of the back-arc portion of the Famatinian Orogen exposed in the southern Sierra de Aconquija (Cuesta de La Chilca segment) in the Sierras Pampeanas Orientales (Eastern Pampean Sierras). The Pampeanas Orientales include from north to south the Aconquija, Ambato and Ancasti mountains. They are mainly composed of middle to high grade metasedimentary units and magmatic rocks. At the south end of the Sierra de Aconquija, along an east to west segment extending over nearly 10 km (Cuesta de La Chilca), large volumes of metasedimentary rocks crop out. The eastern metasediments were defined as members of the El Portezuelo Metamorphic-Igneous Complex (EPMIC) or Eastern block and the western ones relate to the Quebrada del Molle Metamorphic Complex (QMMC) or Western block. The two blocks are divided by the La Chilca Shear Zone, which is reactivated as the Rio Chanarito fault. The EPMIC, forming the hanging wall, is composed of schists, gneisses and rare amphibolites, calc- silicate schists, marbles and migmatites. The rocks underwent multiple episodes of deformation and a late high strain-rate episode with gradually increasing mylonitization to the west. Metamorphism progrades from a M-1 phase to the peak M-3, characterized by the reactions: Qtz + Pl + Bt +/- Ms -> Grt + Bt(2) + Pl(2) +/- Sil +/- Kfs, Qtz + Bt + Sil -> Crd + Kfs and Qtz + Grt + Sil -> Crd. The M-3 assemblage is coeval with the dominant foliation related to a third deformational phase (D-3). The QMMC, forming the foot wall, is made up of fine-grained banded quartz - biotite schists with quartz veins and quartz-feldspar-rich pegmatites. To the east, schists are also overprinted by mylonitization. The M-3 peak assemblage is quartz + biotite + plagioclase +/- garnet +/- sillimanite +/- muscovite +/- ilmenite +/- magnetite +/- apatite. The studied segment suffered multiphase deformation and metamorphism. Some of these phases can be correlated between both blocks. D-1 is locally preserved in scarce outcrops in the EPMIC but is the dominant in the QMMC, where S-1 is nearly parallel to S-0. In the EPMIC, D-2 is represented by the S-2 foliation, related to the F-2 folding that overprints S-1, with dominant strike NNW - SSE and high angles dip to the E. D-3 in the EPMIC have F-3 folds with axis oblique to S-2; the S-3 foliation has striking NW - SE dipping steeply to the E or W and develops interference patterns. In the QMMC, S-2 (D-2) is a discontinuous cleavage oblique to S-1 and transposed by S-3 (D-3), subparallel to S-1. Such structures in the QMMC developed at subsolidus conditions and could be correlated to those of the EPMIC, which formed under higher P-T conditions. The penetrative deformation D-2 in the EPMIC occurred during a prograde path with syntectonic growth of garnet reaching P-T conditions of 640 degrees C and 0.54 GPa in the EPMIC. This stage was followed by a penetrative deformation D-3 with syn-kinematic growth of garnet, cordierite and plagioclase. Peak P-T conditions calculated for M-3 are 710 degrees C and 0.60 GPa, preserved in the western part of the EPMIC, west of the unnamed fault. The schists from the QMMC suffered the early low grade M-1 metamorphism with minimum PT conditions of ca 400 degrees C and 0.35 GPa, comparable to the fine schists (M-1) outcropping to the east. The D-2 deformation is associated with the prograde M-2 metamorphism. The penetrative D-3 stage is related to a medium grade metamorphism M-3, with peak conditions at ca 590 degrees C and 0.55 GPa. The superimposed stages of deformation and metamorphism reaching high P-T conditions followed by isothermal decompression, defining a clockwise orogenic P-T path. During the Lower Paleozoic, folds were superimposed and recrystallization as well as partial melting at peak conditions occurred. Similar characteristics were described from the basement from other Famatinian-dominated locations of the Sierra de Aconquija and other ranges of the Sierras Pampeanas Orientales. KW - Famatinian KW - Sierras Pampeanas Orientales KW - Cuesta de la chilca KW - PT path Y1 - 2021 U6 - https://doi.org/10.1016/j.jsames.2021.103305 SN - 0895-9811 VL - 110 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Altenberger, Uwe A1 - Prosser, Giacomo A1 - Grande, Atonella A1 - Günter, Christina A1 - Langone, Antonio T1 - A seismogenic zone in the deep crust indicated by pseudotachylytes and ultramylonites in granulite-facies rocks of Calabria (Southern Italy) JF - Contributions to mineralogy and petrology N2 - Pseudotachylyte veins frequently associated with mylonites and ultramylonites occur within migmatitic paragneisses, metamonzodiorites, as well as felsic and mafic granulites at the base of the section of the Hercynian lower crust exposed in Calabria (Southern Italy). The crustal section is tectonically superposed on lower grade units. Ultramylonites and pseudotachylytes are particularly well developed in migmatitic paragneisses, whereas sparse fault-related pseudotachylytes and thin mylonite/ultramylonite bands occur in granulite-facies rocks. The presence of sillimanite and clinopyroxene in ultramylonites and mylonites indicates that relatively high-temperature conditions preceded the formation of pseudotachylytes. We have analysed pseudotachylytes from different rock types to ascertain their deep crustal origin and to better understand the relationships between brittle and ductile processes during deformation of the deeper crust. Different protoliths were selected to test how lithology controls pseudotachylyte composition and textures. In migmatites and felsic granulites, euhedral or cauliflower-shaped garnets directly crystallized from pseudotachylyte melts of near andesitic composition. This indicates that pseudotachylytes originated at deep crustal conditions (> 0.75 GPa). In mafic protoliths, quenched needle-to-feather-shaped high-alumina orthopyroxene occurs in contact with newly crystallized plagioclase. The pyroxene crystallizes in garnet-free and garnet-bearing veins. The simultaneous growth of orthopyroxene and plagioclase as well as almandine, suggests lower crustal origin, with pressures in excess of 0.85 GPa. The existence of melts of different composition in the same vein indicates the stepwise, non-equilibrium conditions of frictional melting. Melt formed and intruded into pre-existing anisotropies. In mafic granulites, brittle faulting is localized in a previously formed thin high-temperature mylonite bands. migmatitic gneisses are deformed into ultramylonite domains characterized by s-c fabric. Small grain size and fluids lowered the effective stress on the c planes favouring a seismic event and the consequent melt generation. Microstructures and ductile deformation of pseudotachylytes suggest continuous ductile flow punctuated by episodes of high-strain rate, leading to seismic events and melting. KW - Pseudotachylyte KW - Calabria KW - Lower crust KW - Palaeo-seismicity Y1 - 2013 U6 - https://doi.org/10.1007/s00410-013-0904-3 SN - 0010-7999 VL - 166 IS - 4 SP - 975 EP - 994 PB - Springer CY - New York ER - TY - JOUR A1 - Zobir, Soraya Hadj A1 - Altenberger, Uwe A1 - Günter, Christina T1 - Geochemistry and petrology of metamorphosed submarine basic ashes in the Edough Massif (Cap de Garde, Annaba, northeastern Algeria) JF - Comptes rendus geoscience N2 - The study presents the first evidence of metamorphosed submarine ashes in the Edough Massif, in northeastern Algeria. It occurs below the greenschist-facies Tellian units that represent the thrusted Mesozoic to Eocene passive paleomargin of northern Africa deposited on thinned continental crust. The metamorphic complex consists of tectonically superposed units composed of gneisses (lower unit) and micaschists (upper unit). At the Cap de Garde, these units enclose an "intermediate unit" composed of micaschists and meter-thick layers of marbles, which are sometimes intercalated with amphibolites. The latter occur as discontinuous small lenses and layers. The amphibolites are parallel to the primary bedding of the marbles and the main foliation. Chemical markers and field observations indicate that they are metamorphic equivalents of basic igneous rocks. The lenticular character, low thickness and multiple intercalations with marine sediments and the unusual high lithium concentrations suggest subaqueous near-source basaltic ash-fall deposits in a marine environment. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved. KW - Amphibolites KW - Submarine sediments KW - Basaltic ash-fall deposits KW - Edough KW - Algeria Y1 - 2014 U6 - https://doi.org/10.1016/j.crte.2014.09.002 SN - 1631-0713 SN - 1778-7025 VL - 346 IS - 9-10 SP - 244 EP - 254 PB - Elsevier CY - Paris ER - TY - JOUR A1 - Lorenz, Melanie A1 - Altenberger, Uwe A1 - Trumbull, Robert B. A1 - Lira, Raul A1 - Lopez de Luchi, Monica Graciela A1 - Günter, Christina A1 - Eidner, Sascha T1 - Chemical and textural relations of britholite- and apatite-group minerals from hydrothermal REE mineralization at the Rodeo de los Molles deposit, Central Argentina JF - American mineralogist : an international journal of earth and planetary materials N2 - Britholite group minerals (REE,Ca)(5)[(Si,P)O-4](3)(OH,F) are widespread rare-earth minerals in alkaline rocks and their associated metasomatic zones, where they usually are minor accessory phases. An exception is the REE deposit Rodeo de los Molles, Central Argentina, where fluorbritholite-(Ce) (FBri) is the main carrier of REE and is closely intergrown with fluorapatite (FAp). These minerals reach an abundance of locally up to 75 modal% (FBri) and 20 modal% (FAp) in the vein mineralizations. The Rodeo de los Molles deposit is hosted by a fenitized monzogranite of the Middle Devonian Las Chacras-Potrerillos batholith. The REE mineralization consists of fluorbritholite-(Ce), britholite-(Ce), fluorapatite, allanite-(Ce), and REE fluorcarbonates, and is associated with hydrothermal fluorite, quartz, albite, zircon, and titanite. The REE assemblage takes two forms: irregular patchy shaped REE-rich composites and discrete cross-cutting veins. The irregular composites are more common, but here fluorbritholite-(Ce) is mostly replaced by REE carbonates. The vein mineralization has more abundant and better-preserved britholite phases. The majority of britholite grains at Rodeo de los Molles are hydrothermally altered, and alteration is strongly enhanced by metamictization, which is indicated by darkening of the mineral, loss of birefringence, porosity, and volume changes leading to polygonal cracks in and around altered grains. A detailed electron microprobe study of apatite-britholite minerals from Rodeo de los Molles revealed compositional variations in fluorapatite and fluorbritholite-(Ce) consistent with the coupled substitution of REE3+ + Si4+ = Ca2+ + P5+ and a compositional gap of similar to 4 apfu between the two phases, which we interpret as a miscibility gap. Micrometer-scale intergrowths of fluorapatite in fluorbritholite-(Ce) minerals and vice versa are chemically characterized here for the first time and interpreted as exsolution textures that formed during cooling below the proposed solvus. KW - Britholite KW - apatite KW - exsolution textures KW - miscibility gap KW - compositional gap KW - REE KW - fenite KW - alkaline granites KW - hydrothermal alteration Y1 - 2019 U6 - https://doi.org/10.2138/am-2019-6969 SN - 0003-004X SN - 1945-3027 VL - 104 IS - 12 SP - 1840 EP - 1850 PB - Mineralogical Society of America CY - Chantilly ER - TY - JOUR A1 - Eugenia Cisterna, Clara A1 - Altenberger, Uwe A1 - Mon, Ricardo A1 - Günter, Christina A1 - Gutierrez, Adolfo Antonio T1 - The metamorphic basement of the southern Sierra de Aconquija, Eastern Sierras Pampeanas BT - Provenance and tectonic setting of a Neoproterozoic back-arc basin JF - Journal of South American earth sciences N2 - The Eastern Sierras Pampeanas are mainly composed of Neoproterozoic-early Palaeozoic metamorphic complexes whose protoliths were sedimentary sequences deposited along the western margin of Gondwana. South of the Sierra de Aconquija, Eastern Sierras Pampeanas, a voluminous metamorphic complex crops out. It is mainly composed of schists, gneisses, marbles, calk-silicate schists, thin layers of amphibolites intercalated with the marbles and granitic veins. The new data correlate the Sierra de Aconquija with others metamorphic units that crop out to the south, at the middle portion of the Sierra de Ancasti. Bulk rock composition reflects originally shales, iron rich shales, wackes, minor litharenites and impure limestones as its protoliths. Moreover, comparisons with the northern Sierra de Aconquija and from La Majada (Sierra de Ancasti) show similar composition. Amphibolites have a basaltic precursor, like those from the La Majada (Sierra de Ancasti) ones. The analyzed metamorphic sequence reflects low to moderate weathering conditions in the sediments source environment and their chemical composition would be mainly controlled by the tectonic setting of the sedimentary basin rather than by the secondary sorting and reworking of older deposits. The sediments composition reveal relatively low maturity, nevertheless the Fe - shale and the litharenite show a tendency of minor maturity among them. The source is related to an acid one for the litharenite protolith and a more basic to intermediate for the other rocks, suggesting a main derivation from intermediate to felsic orogen. The source of the Fe shales may be related to and admixture of the sediments with basic components. Overall the composition point to an upper continental crust as the dominant sediment source for most of the metasedimentary rocks. The protolith of the amphibolites have basic precursors, related to an evolving back-arc basin. The chemical data in combination with the specific sediment association (wackes, shales, Fe-shales and minor litharenites) are characteristic for turbidity currents deposits along tectonically active region. They are also commonly associated with calcareous clays (marbles), commonly observed in the evolution of basins with slope and shelf derived carbonate turbidites. The amphibolites members are probably derived from lava-flows synchronous with the sedimentation during the basin evolution. The basin was controlled by a continental island arc possible evolving to a back-arc setting, as indicated for the mixed nature of the inferred source. The metasedimentary sequence from the Cuesta de La Chilca have petrographic, structural and strong chemical similarities, building a north-south striking belt from the north of the Sierra de Aconquija and to the south along the Sierra de Ancasti (La Majada area). The observed similarities allow to present this portion of the Eastern Sierras Pampeanas as a crustal block that records the sedimentary sequences developed along the geodynamic context of the southwestern margin of Gondwana during the Neoproterozoic and Early Palaeozoic. (C) 2017 Elsevier Ltd. All rights reserved. KW - Metasedimentary succession KW - Geochemical records KW - Sierra de Aconquija KW - Eastern Sierras Pampeanas KW - NW Argentina Y1 - 2017 U6 - https://doi.org/10.1016/j.jsames.2017.09.028 SN - 0895-9811 VL - 82 SP - 292 EP - 310 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Lopez, Jose P. A1 - Altenberger, Uwe A1 - Bellos, Laura I. A1 - Günter, Christina T1 - The Cumbres Calchaquies Range (NW-Argentina) BT - Geochemical sedimentary provenance, tectonic setting and metamorphic evolution of a Neoproterozoic sedimentary basin JF - Journal of South American earth sciences N2 - The Cumbres Calchaquies Range forms part of the Famatinian metamorphic basement of the Eastern Sierras Pampeanas. The sedimentary protoliths of the metamorphic sequence were deposited in a marine basin alongside the western margin of Gondwana during the Neoproterozoic. New petrologic, geochemical and thermobarometric data give insight into the evolution of the sedimentary basin, its sediment source area, its later metamorphic overprint and its regional relationship to other parts of the Famatinian basement. The metamorphic series studied here consists of banded schists and gneisses and rare calcsilcate-rocks and migmatites that have been reworked by mid-to deep-crustal metamorphic and tectonic processes. The bulk rock compositions indicate shale, wacke, marl and litharenitic protoliths. The metamorphosed elastic sediments have major and trace element compositions indicating a continental granitoid-dominated source area with low sediment recycling. Low SiO2/Al2O3 ratios suggest a relatively low maturity of the sedimentary protoliths. Therefore, the Cumbres Calchaquies section represents a sequence of turbidity currents with progressive shallowing of the depositional environment, as indicated by quartz- and carbonate-rich sediments. The overall data are consistent with the geodynamic environment of a basin adjacent to a continental magmatic arc as the most probable scenario. Whereas the sedimentary protoliths of the metamorphic basement in the Sierra de Ancasti and Sierra de Aconquija, located ca 100-300 km south of the study area are interpreted as originating in an evolving back-arc basin, our results from the Cumbres Calchaquies region indicate a sedimentary source in a felsic continental arc with no significant influx of basic rocks. The Famatinian metamorphic evolution of the Cumbres Calchaquies rocks is of typical Barrow-type, culminating in partial melting of the metasediments. Conventional thermobarometry combined with thermodynamic models (pseudosections) reveal a prograde evolution reaching peak conditions of ca 665 degrees C/6.1 Kbar. This implies a geothermal gradient of ca 35 degrees C/km, which is slightly higher than the average for continental crust and suggests a period of crustal thinning, as known from back-arc basins, or additional heat supply by voluminous intrusions. KW - NW Argentina KW - Eastern Sierras Pampeanas KW - Cumbres Calchaquies KW - Geothermobarometry KW - Geochemistry KW - Metamorphic evolution KW - Provenance studies Y1 - 2019 U6 - https://doi.org/10.1016/j.jsames.2019.03.016 SN - 0895-9811 VL - 93 SP - 480 EP - 494 PB - Elsevier CY - Oxford ER - TY - JOUR A1 - Zozulya, Dmitry R. A1 - Kullerud, Kare A1 - Ribacki, Enrico A1 - Altenberger, Uwe A1 - Sudo, Masafumi A1 - Savchenko, Yevgeny E. T1 - The newly discovered neoproterozoic aillikite occurrence in Vinoren (Southern Norway) BT - age, geodynamic position and mineralogical evidence of diamond-bearing mantle source JF - Minerals N2 - During the period 750-600 Ma ago, prior to the final break-up of the supercontinent Rodinia, the crust of both the North American Craton and Baltica was intruded by significant amounts of rift-related magmas originating from the mantle. In the Proterozoic crust of Southern Norway, the 580 Ma old Fen carbonatite-ultramafic complex is a representative of this type of rocks. In this paper, we report the occurrence of an ultramafic lamprophyre dyke which possibly is linked to the Fen complex, although Ar-40/Ar-39 data from phenocrystic phlogopite from the dyke gave an age of 686 +/- 9 Ma. The lamprophyre dyke was recently discovered in one of the Kongsberg silver mines at Vinoren, Norway. Whole rock geochemistry, geochronological and mineralogical data from the ultramafic lamprophyre dyke are presented aiming to elucidate its origin and possible geodynamic setting. From the whole-rock composition of the Vinoren dyke, the rock could be recognized as transitional between carbonatite and kimberlite-II (orangeite). From its diagnostic mineralogy, the rock is classified as aillikite. The compositions and xenocrystic nature of several of the major and accessory minerals from the Vinoren aillikite are characteristic for diamondiferous rocks (kimberlites/lamproites/UML): Phlogopite with kinoshitalite-rich rims, chromite-spinel-ulvospinel series, Mg- and Mn-rich ilmenites, rutile and lucasite-(Ce). We suggest that the aillikite melt formed during partial melting of a MARID (mica-amphibole-rutile-ilmenite-diopside)-like source under CO2 fluxing. The pre-rifting geodynamic setting of the Vinoren aillikite before the Rodinia supercontinent breakup suggests a relatively thick SCLM (Subcontinental Lithospheric Mantle) during this stage and might indicate a diamond-bearing source for the parental melt. This is in contrast to the about 100 Ma younger Fen complex, which were derived from a thin SCLM. KW - aillikite KW - phlogopite KW - carbonate KW - spinel KW - ilmenite KW - titanite KW - diamond KW - Vinoren KW - Southern Norway Y1 - 2020 U6 - https://doi.org/10.3390/min10111029 SN - 2075-163X VL - 10 IS - 11 PB - MDPI CY - Basel ER - TY - JOUR A1 - Ribacki, Enrico A1 - Trumbull, Robert B. A1 - Lopez De Luchi, Monica Graciela A1 - Altenberger, Uwe T1 - The chemical and B-Isotope composition of Tourmaline from intra-granitic Pegmatites in the Las Chacras-Potrerillos Batholith, Argentina JF - The Canadian mineralogist : journal of the Mineralogical Association of Canada N2 - The Devonian Las Chacras-Potrerillos batholith comprises six nested monzonitic to granitic intrusions with metaluminous to weakly peraluminous composition and a Sr-Nd isotopic signature indicating a dominantly juvenile mantle-derived source. The chemically most evolved units in the southern batholith contain a large number of intra-granitic, pod-shaped tourmaline-bearing pegmatites. This study uses in situ chemical and boron isotopic analyses of tourmaline from nine of these pegmatites to discuss their relationship to the respective host intrusions and the implications of their B-isotope composition for the source and evolution of the magmas. The tourmalines reveal a diversity in element composition (e.g., FeO, MgO, TiO2, CaO, MnO, F) which distinguishes individual pegmatites from one another. However, all have a narrow 5 11 B range of -13.7 to -10.5%0 (n = 100) which indicates a relatively uniform magmatic system and similar temperature conditions during tourmaline crystallization. The average delta(11) B value of -11.7%0 is typical for S-type granites and is within the range reported for peraluminous granites. pegmatites, and metamorphic units of the Ordovician basement into which the Las Chacras-Potrerillos batholith intruded. The B-isotope evidence argues for a crustal boron source like that of the Ordovician basement, in contrast to the metaluminous to weakly peraluminous composition and juvenile initial Sr and Nd isotope ratios of the Las Chacras-Potrerillos batholith magmas. We propose that the boron was not derived from the magma source region but was incorporated from dehydration melting of elastic metasedimentary rocks higher up in the crustal column. KW - pegmatite KW - tourmaline KW - SIMS KW - B-isotopes KW - Las Chacras-Potrerillos KW - Sierra de San Luis KW - Argentina Y1 - 2022 U6 - https://doi.org/10.3749/canmin.2100036 SN - 0008-4476 SN - 1499-1276 VL - 60 IS - 1 SP - 49 EP - 66 PB - Association of Canada CY - Ottawa ER - TY - JOUR A1 - Pingel, Heiko A1 - Alonso, Ricardo N. A1 - Altenberger, Uwe A1 - Cottle, John A1 - Strecker, Manfred T1 - Miocene to Quaternary basin evolution at the southeastern Andean Plateau (Puna) margin (ca. 24°S lat, Northwestern Argentina) JF - Basin research N2 - The Andean Plateau of NW Argentina is a prominent example of a high-elevation orogenic plateau characterized by internal drainage, arid to hyper-arid climatic conditions and a compressional basin-and-range morphology comprising thick sedimentary basins. However, the development of the plateau as a geomorphic entity is not well understood. Enhanced orographic rainout along the eastern, windward plateau flank causes reduced fluvial run-off and thus subdued surface-process rates in the arid hinterland. Despite this, many Puna basins document a complex history of fluvial processes that have transformed the landscape from aggrading basins with coalescing alluvial fans to the formation of multiple fluvial terraces that are now abandoned. Here, we present data from the San Antonio de los Cobres (SAC) area, a sub-catchment of the Salinas Grandes Basin located on the eastern Puna Plateau bordering the externally drained Eastern Cordillera. Our data include: (a) new radiometric U-Pb zircon data from intercalated volcanic ash layers and detrital zircons from sedimentary key horizons; (b) sedimentary and geochemical provenance indicators; (c) river profile analysis; and (d) palaeo-landscape reconstruction to assess aggradation, incision and basin connectivity. Our results suggest that the eastern Puna margin evolved from a structurally controlled intermontane basin during the Middle Miocene, similar to intermontane basins in the Mio-Pliocene Eastern Cordillera and the broken Andean foreland. Our refined basin stratigraphy implies that sedimentation continued during the Late Mio-Pliocene and the Quaternary, after which the SAC area was subjected to basin incision and excavation of the sedimentary fill. Because this incision is unrelated to baselevel changes and tectonic processes, and is similar in timing to the onset of basin fill and excavation cycles of intermontane basins in the adjacent Eastern Cordillera, we suspect a regional climatic driver, triggered by the Mid-Pleistocene Climate Transition, caused the present-day morphology. Our observations suggest that lateral orogenic growth, aridification of orogenic interiors, and protracted plateau sedimentation are all part of a complex process chain necessary to establish and maintain geomorphic characteristics of orogenic plateaus in tectonically active mountain belts. KW - Andean Plateau KW - NW Argentina KW - Puna KW - river incision KW - sediment routing KW - surface processes Y1 - 2019 U6 - https://doi.org/10.1111/bre.12346 SN - 0950-091X SN - 1365-2117 VL - 31 IS - 4 SP - 808 EP - 826 PB - Wiley CY - Hoboken ER -