Abstract
The Middle-Late Triassic Yanchang Formation, present in the large intracratonic Ordos Basin, is built of alternating sandstones, mudstones, and tuffs, representing a complete lacustrine cycle. Cores from wells in the south-western part of the basin show various types of soft-sediment deformation structures, particularly contorted lamination/bedding, load casts, and associated structures (flame structures, pseudonodules), penecontemporaneous faults, injection structures, and sandy and muddy slumps. They originated by liquefaction and fluidization of unconsolidated sediments, as well as by brittle fracturing of semiconsolidated sediments. Seismic events resulting from synsedimentary tectonic activity were the main triggers but sedimentary overloading may locally have been a minor trigger. The volcanic tuffs support tectono-volcanic activity. The deformation structures are clustered in three stratigraphic levels, indicating phases of intensified seismic activity. A thick extensive oil shale, with various deformation structures, reveals another active tectonic phase. These four intervals coincide well with the transition of the sedimentary architecture in the area.
Original language | English (US) |
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Title of host publication | The Ordos Basin |
Subtitle of host publication | Sedimentological Research for Hydrocarbons Exploration |
Publisher | Elsevier |
Pages | 371-393 |
Number of pages | 23 |
ISBN (Electronic) | 9780323852647 |
ISBN (Print) | 9780323852654 |
DOIs | |
State | Published - Jan 1 2021 |
Keywords
- Lake evolution
- Ordos Basin
- Soft-sediment deformation structures
- Tectono-volcanic activity
- Yanchang Formation
ASJC Scopus subject areas
- General Economics, Econometrics and Finance
- General Business, Management and Accounting