TY - JOUR A1 - Bahr, André A1 - Kolber, Gilles A1 - Kaboth-Bahr, Stefanie A1 - Reinhardt, Lutz A1 - Friedrich, Oliver A1 - Pross, Jörg T1 - Mega-monsoon variability during the late Triassic BT - re-assessing the role of orbital forcing in the deposition of playa sediments in the Germanic Basin JF - Sedimentology : the journal of the International Association of Sedimentologists N2 - The formation of the supercontinent Pangaea during the Permo-Triassic gave rise to an extreme monsoonal climate (often termed 'mega-monsoon') that has been documented by numerous palaeo-records. However, considerable debate exists about the role of orbital forcing in causing humid intervals in an otherwise arid climate. To shed new light on the forcing of monsoonal variability in subtropical Pangaea, this study focuses on sediment facies and colour variability of playa and alluvial fan deposits in an outcrop from the late Carnian (ca 225 Ma) in the southern Germanic Basin, south-western Germany. The sediments were deposited against a background of increasingly arid conditions following the humid Carnian Pluvial Event (ca 234 to 232 Ma). The ca 2 center dot 4 Myr long sedimentary succession studied shows a tripartite long-term evolution, starting with a distal mud-flat facies deposited under arid conditions. This phase was followed by a highly variable playa-lake environment that documents more humid conditions and finally a regression of the playa-lake due to a return of arid conditions. The red-green (a*) and lightness (L*) records show that this long-term variability was overprinted by alternating wet/dry cycles driven by orbital precession and ca 405 kyr eccentricity, without significant influence of obliquity. The absence of obliquity in this record indicates that high-latitude forcing played only a minor role in the southern Germanic Basin during the late Carnian. This is different from the subsequent Norian when high-latitude signals became more pronounced, potentially related to the northward drift of the Germanic Basin. The recurring pattern of pluvial events during the late Triassic demonstrates that orbital forcing, in particular eccentricity, stimulated the occurrence and intensity of wet phases. It also highlights the possibility that the Carnian Pluvial Event, although most likely triggered by enhanced volcanic activity, may also have been modified by an orbital stimulus. KW - Carnian Pluvial Event KW - Germanic Basin KW - Late Triassic KW - mega-monsoon KW - orbital forcing KW - playa-lake Y1 - 2019 U6 - https://doi.org/10.1111/sed.12668 SN - 0037-0746 SN - 1365-3091 VL - 67 IS - 2 SP - 951 EP - 970 PB - Wiley-Blackwell CY - Oxford ER - TY - JOUR A1 - Elling, Felix J. A1 - Spiegel, Cornelia A1 - Estrada, Solveig A1 - Davis, Donald W. A1 - Reinhardt, Lutz A1 - Henjes-Kunst, Friedhelm A1 - Allroggen, Niklas A1 - Dohrmann, Reiner A1 - Piepjohn, Karsten A1 - Lisker, Frank T1 - Origin of Bentonites and Detrital Zircons of the Paleocene Basilika Formation, Svalbard JF - Frontiers in Earth Science N2 - The Paleocene was a time of transition for the Arctic, with magmatic activity of the High Arctic Large Igneous Province (HALIP) giving way to magmatism of the North Atlantic Large Igneous Province in connection to plate tectonic changes in the Arctic and North Atlantic. In this study we investigate the Paleocene magmatic record and sediment pathways of the Basilika Formation exposed in the Central Tertiary Basin of Svalbard. By means of geochemistry, SmNd isotopic signatures, and zircon UPb geochronology we investigate the characteristics of several bentonite layers contained in the Basilika Formation, as well as the provenance of the intercalated clastic sediments. Our data show that the volcanic ash layers of the Basilika Formation, which were diagenetically altered to bentonites, originate from alkaline continental-rift magmatism such as the last, explosive stages of the HALIP in North Greenland and the Canadian Arctic. The volcanic ash layers were deposited on Svalbard in a flat shelf environment with dominant sediment supply from the east. Dating of detrital zircons suggests that the detritus was derived from Siberian sources, primarily from the Verkhoyansk Fold-and-Thrust Belt, which would require transport over similar to 3000 km across the Arctic. KW - Paleogene KW - Svalbard KW - Central Tertiary Basin KW - Basilika formation KW - bentonite KW - zircon provenance KW - High Arctic Large Igneous Province KW - North Atlantic Large Igneous Province Y1 - 2016 U6 - https://doi.org/10.3389/feart.2016.00073 SN - 2296-6463 VL - 4 PB - Frontiers Research Foundation CY - Lausanne ER -