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Genesis and implications of the composition and sedimentary structure of fine-grained carbonate rocks in the Shulu sag
- Source :
- Journal of Earth Science. 28:1047-1063
- Publication Year :
- 2017
- Publisher :
- Springer Science and Business Media LLC, 2017.
-
Abstract
- Fine-grained carbonate rocks, which extensively occur in the Eocene strata in the Shulu sag, Bohai Bay Basin, North China, represent an unconventional, fine-grained carbonate reservoir. However, previous studies have ignored the complexity of the lithofacies components and their formation mechanisms. Fine-grained carbonate rocks are typical reservoirs in which hydrocarbons form and gather. A better understanding of the nature of these rocks is extremely important for evaluating the quality of unconventional, fine-grained carbonate reservoirs. Various lithofacies components were discriminated in this study with a combination of petrographic observations and carbon isotope analyses. These finegrained carbonate rocks comprise terrigenous, biogenic and diagenetic materials. Terrigenous input and biologically induced precipitation are the main sources of the materials in the lake. Five lithofacies were identified based on the observations of sedimentary features (core and thin section) and mineralogical data: (1) varve-like laminated calcilutite, (2) graded laminated calcilutite, (3) interlaminated calcisiltitecalcilutite, (4) massive calcilutite, and (5) massive calcisiltite-calcarenite. Their origins were recorded by various lithofacies components, which are controlled by the interactions of physical, chemical and biological processes. This study indicated that the lithology of the bedrocks was the key factor controlling carbonate accumulation. The tectonics and climate can influence the weathering and types of lithofacies. Primary productivity controlled the precipitation of the endogenic calcite. These factors jointly determined the abundant fine-grained carbonate rocks that have accumulated in the Shulu sag.
- Subjects :
- Terrigenous sediment
020209 energy
Geochemistry
Weathering
02 engineering and technology
010502 geochemistry & geophysics
01 natural sciences
Diagenesis
Petrography
chemistry.chemical_compound
Calcilutite
chemistry
0202 electrical engineering, electronic engineering, information engineering
General Earth and Planetary Sciences
Carbonate
Carbonate rock
Sedimentary rock
Geology
0105 earth and related environmental sciences
Subjects
Details
- ISSN :
- 1867111X and 1674487X
- Volume :
- 28
- Database :
- OpenAIRE
- Journal :
- Journal of Earth Science
- Accession number :
- edsair.doi...........986d394c4c1a2672c85797df5a8cb4cf