Sedimentary environment and geochemical characteristics of Shahejie Formation in Huimin Sag, Bohai bay basin, China
- PDF / 4,202,499 Bytes
- 12 Pages / 595.276 x 790.866 pts Page_size
- 5 Downloads / 204 Views
ORIGINAL PAPER
Sedimentary environment and geochemical characteristics of Shahejie Formation in Huimin Sag, Bohai bay basin, China Li Cunlei 1
&
Wang Lingling 1 & Chen Panpan 1
Received: 14 February 2020 / Accepted: 10 September 2020 # Saudi Society for Geosciences 2020
Abstract The Shahejie Formation in Huimin Sag is an important crude oil/natural gas reservoir stratum. The results show that (1) in the study area, the Sr/Ba value of Shahejie Formation ES4, ES3, and ES2 in Huimin Sag is 0.55–0.58, showing that these were freshwater-brackish water environment with a continental deposition; the average Sr/Ba value of the first member of Shahejie Formation (ES1) is 1.88, showing that it was a salt water environment. (2) B element method of paleo-salinity analysis shows that in ancient times, the salinity of ES1 was the highest; ES2 and ES4 had basically the same salinity that were lower than that of ES1; the third formation of Shahejie Formation(ES3) had the lowest salinity. (3) Analysis of values of Fe/Mn, Mg/Ca, and paleoclimate index C shows that the Shahejie Formation had generally a semi-dry climate. (4) Based on the analysis of the paleoenvironment, combined with the description of the cores, a sedimentary evolution model is built: ES4 was a debris flow fanshaped river delta sediment in a shallow lake environment; ES3 was a delta-deep water fan-shaped system in a semi-deep-deep lake environment; ES2 was a delta system in semi-shallow lake environment; ES1 is the semi-shallow lake environment, the main sedimentary facies is the shore shallow lake facies. Keywords Huimin Sag . Geochemistry . Paleoclimate . Paleo-salinity . Sedimentary environment . Element
Introduction Among many factors that affect elemental composition of rocks, the physicochemical conditions (including temperature, salinity, Eh and pH values, depth, etc.) of lake basin (sea) water bodies that are closely related to basin paleogeography and paleoclimatic conditions are one of the important controlling factors of element collection and distribution, especially for trace elements (Li et al. 2008; Chen et al. 2013; RamosVázquez et al. 2017; Ramos-Vazquez et al. 2018; AnayaGregorio et al. 2018). Conversely, the elemental content and elemental ratio in mudstone indicate the sedimentary environment and the paleo-salinity and paleoclimatic characteristics to certain extent (Chen et al. 2020; Armstrong-Altrin et al. 2018; Responsible Editor: Domenico M. Doronzo * Li Cunlei [email protected] 1
College of Petroleum Engineering, Liaoning Shihua University, Fushun 113001, China
Ramos-Vazquez et al. 2018). Some elements may also have a relative “stability” during diagenesis and are less affected by secondary changes (such as boron that enters the clay mineral lattice) (Wang 2005). Therefore, the sedimentary and environmental significance of these chemical elements is quite obvious. The chemical composition of sediments in different sedimentary environments is rather different; the change of element content can reflect the change of sedimentary env
Data Loading...
