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Sediments and Sedimentary Rocks
Published in Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough, Earth Materials, 2019
Dexter Perkins, Kevin R. Henke, Adam C. Simon, Lance D. Yarbrough
Lithic sandstones are sandstones with clasts that are more than 5% of rock fragments. The presence of feldspar or lithic fragments in sandstone implies that the parent sediment did not travel far from its source before deposition, or else the feldspar or fragments would have decomposed or broken apart.
Characteristics of fluid potential and the division of hydrocarbon migration and accumulation units in the Nangong Sag, Bohai Bay Basin, China
Published in Petroleum Science and Technology, 2022
Tianshun Liu, Wenlong Ding, Zhanwen Yu, Jingtian Li, Sicheng Wang, Xu Zhou, Xiaoyun Cheng
Analysis of the petroleum system events in the study area (Figure 6a) indicates that the Nangong Sag has a good source-reservoir-cap configuration and favorable migration and accumulation conditions. The Es3 source rock in the study area is medium and good source rock, with TOC of 0.26–2.06% and hydrocarbon generation potential of 0.12–10.88 mg/g. They are mainly composed of type II2 and type III kerogen. The threshold value of hydrocarbon generation of source rocks is 2200 m–2400m. The main reservoir types are lithic arkose and feldspathic lithic sandstone, followed by lithic sandstone and arkose, and the porosity of the reservoir is 10.7–23.9%. Structural traps were mainly formed in Eocene and Oligocene. The Pliocene and later is the main period of hydrocarbon generation and hydrocarbon expulsion of Es3 source rock. The period of hydrocarbon generation and migration is later than the trap formation period, and the intensity of tectonic activity is relatively stable after Pliocene, which has little transformation effect on the early formed folds and little damage to the early structural traps. Therefore, the study area has a good time allocation relationship of hydrocarbon.
Sedimentary environment and facies of the Huagang Formation in the northern central Xihu Depression, East China Sea Basin, China
Published in Australian Journal of Earth Sciences, 2020
Z. X. Zhao, C. M. Dong, C. Y. Lin, X. G. Zhang, X. Huang, B. J. Li, W. Guo, Z. Q. Zhu
The target layer consists of two sets of grey-white, thick-bedded, sandstone bodies with a total thickness of approximately 100 m, interlayered with three layers of mudstones that contain thin sandstones interbeds. The sandstone bodies are evenly distributed on the plane. Multiple sets of mudstones, generally not more than 2 m thick, develop inside the sand bodies (Figure 1). The main rock type, a feldspar–lithic–quartz sandstone, which contains a small amount of feldspathic lithic sandstone and lithic sandstone (Figure 2), is relatively uniform, with little change in the amounts of quartz (63–65 vol%), feldspar (50–75 vol%) and lithic fragments (18–20 vol%). The structure has a moderate degree of maturity, with a subangular–subcircular-shaped particles with mostly moderate–good sorting.
Modelling of bauxite seam attributes and quantifying in-situ ore volume uncertainty in the presence of geophysical information
Published in Applied Earth Science, 2020
Oktay Erten, Didier Renard, Lachlan McAndrew
Bauxite, whose thickness ranges from to across Weipa plateau, is underlain by a classical laterite profile and overlain in topographically low areas by the sediments including red soil, and the soil overlies the whole sequence (Morgan 1995). Bauxite at Weipa was originated from two types of sedimentary rocks: (1) the Rolling Downs Group, and (2) the Bulimba Formation (Morgan 1996). The former was formed in a shallow marine environment, and is composed of marine claystone, mudstone, siltstone, lithic sandstone and minor quartz sandstone. These sediments are the parent rocks for the Andoom type bauxite. The latter is composed of tertiary or upper Cretaceous unconsolidated fluviatile sands, and lies on top of the Rolling Downs Group. The Weipa type bauxite was formed by the weathering of the Bulimba Formation (Schaap 1990).