Sequence stratigraphy of a Paleogene coal bearing rim syncline

Interplay of salt dynamics and sea-level changes, Schöningen, Germany

authored by

Ariana Osman, Lukas Pollok, Christian Brandes, Jutta Winsemann

Abstract

Salt rim synclines contain important hydrocarbon and coal resources in central Europe. The Schöningen salt rim syncline is filled with >300 m of Early to Middle Eocene unconsolidated clastics with interbedded lignitic coal seams that are mined at the surface. In this study, 357 lithologic logs are integrated with measured outcrop sections and paleo-botanical data to interpret the depositional environments and sequence stratigraphic framework of the rim syncline fill. As salt withdrew, it generated an elongate mini-basin that mimicked an incised valley. The sustained accommodation and slow broadening of the syncline affected the stratigraphic architecture and contributed to the preservation of coal units. The clastic units in the syncline filled in seven depositional stages: (1) tidally influenced fluvial estuarine channels; (2) mixed tide- and wave- dominated estuaries; (3) prograding wave dominate deltas; (4) transgressive shoreline deposits; (5) braided fluvial channels; (6) estuaries; and (7) prograding tide-dominated channels. The succession defines four 3rd order sequences and several higher order sequences that are possibly related to Milankovitch cycles. The higher order sequences are dominantly characterized by stacked transgressive cycles of thick, lowstand coals overlain by estuarine sands. The nearly continuous warm and wet Eocene climate was conducive to continuous peat production with a climatic overprint recorded in the mire type: ombrotrophic mires developed in wetter times and rheotrophic mires developed in relatively drier conditions pointing to the presence of orbitally controlled seasonality. Both mire types were impacted by the interplay of subsidence and base-level. The continuous dropping of the mires below base-level via subsidence protected the mires against erosion and may account for the absence of coals outside of the rim synclines in the region.

Organisation(s)

Institute of Geology
Quartenary Geology, Clastic Sedimentology, Basin Analysis

Type

Article

Journal

Basin research

Volume

25

Pages

675-708

No. of pages

34

ISSN

0950-091X

Publication date

12.2013

Publication status

Published

Peer reviewed

Yes

ASJC Scopus subject areas

Geology

Sustainable Development Goals

SDG 13 - Climate Action

Electronic version(s)

https://doi.org/10.1111/bre.12021 (Access: Unknown)