首页   按字顺浏览 期刊浏览 卷期浏览 Silicification of calcrete in palaeodrainage basins of the Australian arid zone
Silicification of calcrete in palaeodrainage basins of the Australian arid zone

 

作者: A.V. Arakel,   G. Jacobson,   M. Salehi,   C.M. Hill,  

 

期刊: Australian Journal of Earth Sciences  (Taylor Available online 1989)
卷期: Volume 36, issue 1  

页码: 73-89

 

ISSN:0812-0099

 

年代: 1989

 

DOI:10.1080/14400958908527952

 

出版商: Taylor & Francis Group

 

关键词: palaeodrainage;silcrete-calcrete cogenesis;silica migration;silicified calcrete

 

数据来源: Taylor

 

摘要:

Quaternary calcrete deposits in palaeodrainage basins of the arid zone of Western and central Australia have developed near the surface within a remarkably short span of time. Silicification of the calcrete, involving the filling of voids and replacement of calcite by opaline and quartzose silica, has taken place in both the vadose and phreatic hydrological zones as a late diagenetic event. Diagenetic changes in the textures of silicified calcrete commonly correspond with silica-phase transformation and reflect replacement of carbonate through dissolution and reprecipitation. Silicified calcrete horizons in ancient terrestrial (lacustrine and groundwater) carbonate deposits may be related to the migration history of the silica in palaeohydrological systems. The presence of silica as thin grain coatings, veins and pore and cavity linings is a manifestation of the intricate balance between the solution of host calcrete and precipitation of silica under prevailing arid/semi-arid hydrological conditions. Such cogenesis, although spatially highly variable, has an important bearing on preservation and redistribution of economic mineral ores, and on the occurrence of fresh groundwater aquifers in the internal drainage basins of Australia.

 

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