Physical properties of four profiles from the Triassic in Germany

The Norian Steinmergel-Keuper (SMK) represents a low-latitude cyclically-bedded playa system of the Mid-German Basin. We investigated a drilling site (core Morsleben) and sections from marginal positions. Dolomite/red mudstone beds form rhythmic alternations that were associated with varying monsoon activity. Hence, low K/Al ratios of dolomite beds suggest increased chemical weathering of the crystalline hinterland and therefore increased monsoonal rainfall. High K/Al ratios in red mudstone beds reflect increased physical weathering of the hinterlands during dryer periods. Dolomite layers reflect the lake stage (maximum monsoon) while red mudstones indicate the dry phase (minimum monsoon) of the playa cycle. We distinguished five major types of cyclic facies alternations, representing specific facies zones in the playa system. We have implemented spectrophotometry as a tool for high-resolution cyclostratigraphy. The dense sampling increment (up to 1 cm) allows for the recognition of all orbital frequencies. Sediment colour profiles reveal striking hierarchical cycles from semi-precession (SP, 99 kyr) over precession (P, 19.8 kyr) and obliquity (O, 36 kyr) to eccentricity (E1-2 109 kyr; E3, 413 kyr). A significant about 2 Myr-signal is attributed to the longer-term eccentricity E4. One monsoonal (precession) cycle includes two carbonate precipitation events. We propose that stratified mudstone and red mudstone are associated with maximum and minimum monsoon during the transition of the solstices in perihelion and aphelion, respectively. The two carbonate precipitation events were most likely created when equinoxes were in perihelion and aphelion, respectively. A sedimentary semi-precession response cycle is a novel finding for the Norian strata. The obliquity signal is attributed to incoming atmospheric moisture from the northeast of the SMK basin. The E4 cycle controls lake-level changes over long times. Apparently, E4 is responsible whether or not a threshold value is crossed. Bundles of 109 kyr and 413 kyr in red mudstones suggest a dry system with reduced monsoonal activity. In contrast, humid periods reveal thick layers of dolomite beds, indicating that during those intervals the monsoonal activity was strong enough to prevent the playa system from drying out completely.

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Vollmer, Thorsten, Ricken, Werner, Weber, Michael E, Tougiannidis, Nikolaos, Röhling, Heinz-Gerd, Hambach, Ulrich (2008). Dataset: Physical properties of four profiles from the Triassic in Germany. https://doi.org/10.1594/PANGAEA.735776

DOI retrieved: 2008

Additional Info

Field Value
Imported on November 30, 2024
Last update November 30, 2024
License CC-BY-3.0
Source https://doi.org/10.1594/PANGAEA.735776
Author Vollmer, Thorsten
Given Name Thorsten
Family Name Vollmer
More Authors
Ricken, Werner
Weber, Michael E
Tougiannidis, Nikolaos
Röhling, Heinz-Gerd
Hambach, Ulrich
Source Creation 2008
Publication Year 2008
Resource Type application/zip - filename: vollmer_2008
Subject Areas
Name: LandSurface

Name: Lithosphere

Name: Paleontology

Related Identifiers
Title: Orbital control on Upper Triassic Playa cycles of the Steinmergel-Keuper (Norian): A new concept for ancient playa cycles
Identifier: https://doi.org/10.1016/j.palaeo.2007.12.017
Type: DOI
Relation: IsSupplementTo
Year: 2008
Source: Palaeogeography, Palaeoclimatology, Palaeoecology
Authors: Vollmer Thorsten , Ricken Werner , Weber Michael E , Tougiannidis Nikolaos , Röhling Heinz-Gerd , Hambach Ulrich .