10.1594/PANGAEA.735776
Vollmer, Thorsten
Thorsten
Vollmer
Ricken, Werner
Werner
Ricken
Weber, Michael E
Michael E
Weber
0000-0003-2175-8980
Tougiannidis, Nikolaos
Nikolaos
Tougiannidis
Röhling, Heinz-Gerd
Heinz-Gerd
Röhling
Hambach, Ulrich
Ulrich
Hambach
0000-0001-8455-6812
Physical properties of four profiles from the Triassic in Germany
PANGAEA
2008
Outcrop sample
Core drilling
en
Supplementary Publication Series of Datasets
10.1016/j.palaeo.2007.12.017
6 datasets
application/zip
Creative Commons Attribution 3.0 Unported
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.
Supplement to: Vollmer, Thorsten; Ricken, Werner; Weber, Michael E; Tougiannidis, Nikolaos; Röhling, Heinz-Gerd; Hambach, Ulrich (2008): Orbital control on Upper Triassic Playa cycles of the Steinmergel-Keuper (Norian): A new concept for ancient playa cycles. Palaeogeography, Palaeoclimatology, Palaeoecology, 267(1-2), 1-16
35.301
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Germany