Lithostratigraphy,Sedimentology,and Provenance of the Balfour Formation(Beaufort Group) in the Fort Beaufort-Alice Area,Eastern Cape Province,South Africa  

作　　者：David KATEMAUNZANGA Cornelis Janse GUNTER 

机构地区：[1]Council for Geoscience,Pretoria,South Africa [2]Geology Department,University of Fort Hare,Alice,South Africa

出　　处：《Acta Geologica Sinica(English Edition)》2009年第5期902-916,共15页地质学报（英文版）

基　　金：supported by the Govan Mbeki Research Centre(GMRC) at the University of Fort Hare and by the Council for Geoscience

摘　　要：The Balfour Formation has a pronounced lithological variation that is characterized by alternating sandstone- and mudstone-dominated members. The sandstone-dominated Oudeberg and Barberskrans Members are composed of lithofacies that range from intraformationai conglomerates to fine-grained sediments, whereas the mudstone-dominated members （Daggaboersnek, Elandsberg, and Palingkloof） are dominated by the facies Fm and FI. Petrography, geochemistry, and a paleocurrent analysis indicated that the source rock of the Balfour Formation was to south east and the rocks had a transitional/dissected magmatic arc signature. The sandstones-rich members were deposited by seasonal and ephemeral high-energy, low-sinuous streams, and the fine-grained-rich members were formed by ephemeral meandering streams. The paleoclimates have been equated to present temperate climates; they were semiarid becoming arid towards the top of the Balfour Formation. This has been determined by reconstructing the paleolatitude of the Karoo Basin, geochemistry, paleontology, sedimentary structures, and other rock properties, like color.The Balfour Formation has a pronounced lithological variation that is characterized by alternating sandstone- and mudstone-dominated members. The sandstone-dominated Oudeberg and Barberskrans Members are composed of lithofacies that range from intraformationai conglomerates to fine-grained sediments, whereas the mudstone-dominated members （Daggaboersnek, Elandsberg, and Palingkloof） are dominated by the facies Fm and FI. Petrography, geochemistry, and a paleocurrent analysis indicated that the source rock of the Balfour Formation was to south east and the rocks had a transitional/dissected magmatic arc signature. The sandstones-rich members were deposited by seasonal and ephemeral high-energy, low-sinuous streams, and the fine-grained-rich members were formed by ephemeral meandering streams. The paleoclimates have been equated to present temperate climates; they were semiarid becoming arid towards the top of the Balfour Formation. This has been determined by reconstructing the paleolatitude of the Karoo Basin, geochemistry, paleontology, sedimentary structures, and other rock properties, like color.

关 键 词：Balfour Formation Karoo Supergroup Beaufort Group LITHOSTRATIGRAPHY SEDIMENTOLOGY PROVENANCE PERMO-TRIASSIC 

分 类 号：P618.13[天文地球—矿床学]