Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China

Abstract The genesis of the fine crystalline dolomites that exhibit good to excellent reservoir properties in the upper fourth member of the Eocene Shahejie Formation (Es 4 s ) around the Sikou Sag, Bohai Bay Basin, is uncertain. This paper investigates the formation mechanisms of this fine crystall...

Descripción completa

Guardado en:

Detalles Bibliográficos
Autores principales:	Yong-Qiang Yang, Long-Wei Qiu, Jay Gregg, Zheng Shi, Kuan-Hong Yu
Formato:	article
Lenguaje:	EN
Publicado:	KeAi Communications Co., Ltd. 2016
Materias:	Dolomite Lacustrine carbonate Eocene Sikou Sag Bohai Bay Basin Science Q Petrology QE420-499
Acceso en línea:	https://doaj.org/article/992291ec0d474bcdb8bdabf8844ae6fc
Etiquetas:	Agregar Etiqueta Sin Etiquetas, Sea el primero en etiquetar este registro!

id	oai:doaj.org-article:992291ec0d474bcdb8bdabf8844ae6fc
record_format	dspace
spelling	oai:doaj.org-article:992291ec0d474bcdb8bdabf8844ae6fc2021-12-02T00:12:46ZFormation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China10.1007/s12182-016-0128-z1672-51071995-8226https://doaj.org/article/992291ec0d474bcdb8bdabf8844ae6fc2016-11-01T00:00:00Zhttp://link.springer.com/article/10.1007/s12182-016-0128-zhttps://doaj.org/toc/1672-5107https://doaj.org/toc/1995-8226Abstract The genesis of the fine crystalline dolomites that exhibit good to excellent reservoir properties in the upper fourth member of the Eocene Shahejie Formation (Es 4 s ) around the Sikou Sag, Bohai Bay Basin, is uncertain. This paper investigates the formation mechanisms of this fine crystalline dolomite using XRD, SEM, thin section analysis and geochemical data. The stratigraphy of the Sikou lacustrine carbonate is dominated by the repetition of metre-scale, high-frequency deposition cycles, and the amount of dolomite within a cycle increases upward from the cycle bottom. These dolomite crystals are 2–30 μm in length, subhedral to anhedral in shape and typically replace both grains and matrix. They also occur as rim cement and have thin lamellae within ooid cortices. Textural relations indicate that the dolomite predates equant sparry calcite cement and coarse calcite cement. The Sr concentrations of dolomites range from 900 to 1200 ppm. Dolomite δ18O values (−11.3 to −8.2 ‰ PDB) are depleted relative to calcite mudstone (−8.3 to −5.4 ‰ PDB) that precipitated from lake water, while δ13C values (0.06–1.74 ‰ PDB) are within the normal range of calcite mudstone values (−2.13 to 1.99 ‰ PDB). High 87Sr/86Sr values (0.710210–0.710844) indicate that amounts of Ca2+ and Mg2+ have been derived from the chemical weathering of Palaeozoic carbonate bedrocks. The high strontium concentration indicates that hypersaline conditions were maintained during the formation of the dolomites and that the dolomites were formed by the replacement of precursor calcite or by direct precipitation.Yong-Qiang YangLong-Wei QiuJay GreggZheng ShiKuan-Hong YuKeAi Communications Co., Ltd.articleDolomiteLacustrine carbonateEoceneSikou SagBohai Bay BasinScienceQPetrologyQE420-499ENPetroleum Science, Vol 13, Iss 4, Pp 642-656 (2016)
institution	DOAJ
collection	DOAJ
language	EN
topic	Dolomite Lacustrine carbonate Eocene Sikou Sag Bohai Bay Basin Science Q Petrology QE420-499
spellingShingle	Dolomite Lacustrine carbonate Eocene Sikou Sag Bohai Bay Basin Science Q Petrology QE420-499 Yong-Qiang Yang Long-Wei Qiu Jay Gregg Zheng Shi Kuan-Hong Yu Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
description	Abstract The genesis of the fine crystalline dolomites that exhibit good to excellent reservoir properties in the upper fourth member of the Eocene Shahejie Formation (Es 4 s ) around the Sikou Sag, Bohai Bay Basin, is uncertain. This paper investigates the formation mechanisms of this fine crystalline dolomite using XRD, SEM, thin section analysis and geochemical data. The stratigraphy of the Sikou lacustrine carbonate is dominated by the repetition of metre-scale, high-frequency deposition cycles, and the amount of dolomite within a cycle increases upward from the cycle bottom. These dolomite crystals are 2–30 μm in length, subhedral to anhedral in shape and typically replace both grains and matrix. They also occur as rim cement and have thin lamellae within ooid cortices. Textural relations indicate that the dolomite predates equant sparry calcite cement and coarse calcite cement. The Sr concentrations of dolomites range from 900 to 1200 ppm. Dolomite δ18O values (−11.3 to −8.2 ‰ PDB) are depleted relative to calcite mudstone (−8.3 to −5.4 ‰ PDB) that precipitated from lake water, while δ13C values (0.06–1.74 ‰ PDB) are within the normal range of calcite mudstone values (−2.13 to 1.99 ‰ PDB). High 87Sr/86Sr values (0.710210–0.710844) indicate that amounts of Ca2+ and Mg2+ have been derived from the chemical weathering of Palaeozoic carbonate bedrocks. The high strontium concentration indicates that hypersaline conditions were maintained during the formation of the dolomites and that the dolomites were formed by the replacement of precursor calcite or by direct precipitation.
format	article
author	Yong-Qiang Yang Long-Wei Qiu Jay Gregg Zheng Shi Kuan-Hong Yu
author_facet	Yong-Qiang Yang Long-Wei Qiu Jay Gregg Zheng Shi Kuan-Hong Yu
author_sort	Yong-Qiang Yang
title	Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
title_short	Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
title_full	Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
title_fullStr	Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
title_full_unstemmed	Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China
title_sort	formation of fine crystalline dolomites in lacustrine carbonates of the eocene sikou depression, bohai bay basin, east china
publisher	KeAi Communications Co., Ltd.
publishDate	2016
url	https://doaj.org/article/992291ec0d474bcdb8bdabf8844ae6fc
work_keys_str_mv	AT yongqiangyang formationoffinecrystallinedolomitesinlacustrinecarbonatesoftheeocenesikoudepressionbohaibaybasineastchina AT longweiqiu formationoffinecrystallinedolomitesinlacustrinecarbonatesoftheeocenesikoudepressionbohaibaybasineastchina AT jaygregg formationoffinecrystallinedolomitesinlacustrinecarbonatesoftheeocenesikoudepressionbohaibaybasineastchina AT zhengshi formationoffinecrystallinedolomitesinlacustrinecarbonatesoftheeocenesikoudepressionbohaibaybasineastchina AT kuanhongyu formationoffinecrystallinedolomitesinlacustrinecarbonatesoftheeocenesikoudepressionbohaibaybasineastchina
_version_	1718403876999135232

Formation of fine crystalline dolomites in lacustrine carbonates of the Eocene Sikou Depression, Bohai Bay Basin, East China

Ejemplares similares