MINERALOGICAL CHARACTERISTICS OF EAST-AFRICAN (KAROO AND JURASSIC TERTIARY QUESTIONABLE) RIFT-VALLEY SEDIMENTS

被引：3

作者：

DYPVIK, H

NESTEBY, H

机构：

[1] Department of Geology, University of Oslo, 0316 Oslo

[2] IKU Petroleum Research

来源：

JOURNAL OF AFRICAN EARTH SCIENCES | 1992年 / 14卷 / 04期

关键词：

D O I：

10.1016/0899-5362(92)90085-Q

中图分类号：

P [天文学、地球科学];

学科分类号：

07 ;

摘要：

The Karoo (here mainly Permian) beds and Jurassic to Tertiary (?) Red Sandstone Group exhibit petrographical differences reflecting various depositional facies, and different stages of exposure caused by varying tectonic activity and subsequent diagenetic history. These variations are tectonically and climatically controlled by combinations of fault activity (half graben), equatorial plate movements, and climatic changes during the Permian to Jurassic/Tertiary (?) periods. The mica and illite/smectite mixed-layered clay mineral-rich lower Karoo beds represent deposition in a possibly cold to temperate, relatively dry climate with temperatures, lower as compared to the smectite-rich beds of the upper part of the Karoo, which reflect more temperate, semi-arid conditions. In the lower part of Karoo large amounts of kaolinite reworked from both fossil weathering profiles and of diagenetic origin are found. The kaolinite enrichments in the Red Sandstone Group, compared to the upper part of Karoo below, represents chemically-dominated weathering conditions, partially in combination with diagenetic alterations.

引用

页码：527 / 538

页数：12

共 38 条

[1]

Berner, Principles of Chemical Sedimentology, (1971)

[2]

Bjorlykke, Geochemical and mineralogical influence of Ordovician Island Arcs on epicontinental clastic sedimentation A study of Lower Paleozoic sedimentation in the Oslo Region Norway, Sedimentology, 21, pp. 251-272, (1974)

[3]

Brindley, Brown, Crystal structures of Clay minerals and their X-ray identification, Min. Soc. Monog., 5, (1980)

[4]

Briden, Drewry, Smith, Phanerozoic equal-area world maps, The Journal of Geology, 82, pp. 555-574, (1974)

[5]

Buhmann, Lepper, Significant mineral variations in the Lower Karoo deposits of the Mid-Zambezi Basin, Zimbabwe, and their paleoenvironmental implications, S. Afr. J. Geol., 93, pp. 744-753, (1990)

[6]

Buhmann, Lepper, Mineralogy of the Matura Hill Borehole Core, Wankie Concession, Zimbawe, with Special Reference to its Clay Mineral Content, Geol. Jb., 500-596, pp. 55-66, (1990)

[7]

Carrol, Clay Minerals: A Guide to their X-ray identification, Geol. Soc. Am. Spec. Pap., 126, (1970)

[8]

Chinese Petroleum Investigation Team, Report on the investigation of petroleum geology in the U.R. of Tanzania, (1977)

[9]

Dypvik, Mineralogical and geochemical studies of Lower Paleozoic rocks from the Trondheim and Oslo Regions, Norway, Norsk Geol. Tidsskr., 57, pp. 205-241, (1977)

[10]

Dypvik, Clay Mineral Transformations in Tertiary and Mesozoic Sediments from North Sea. Am. Assoc., Pet. Geol. Bull., 67, pp. 160-165, (1983)

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