The formation and origin of carbonate minerals in the Darling and Yzerfontein hypersaline pans, Western Cape, South Africa

The Darling and Yzerfontein hypersaline pans are located on the western coastal plain of South Africa. The area has an arid, Mediterranean type climate. The carbonate minerals calcite and dolomite have precipitated in the pans through the evaporation and concentration of ions derived from weathering of bedrock, marine aerosols and coastal rainfall. Five pans were studied, the brine-type pans Rooipan South, Zwartwater North and Zwartwater South, the brackish saline pan Rooipan North, and the coastal Yzerfontein pan. Directly below the surficial halite crust of the three brine-type pans is a black organic-matter rich layer in which bacterial sulphate reduction is occurring (hydrogen-sulphide smell). All of the pans contain disseminated calcite, with only the Zwartwater North and Zwartwater South pans containing a mixture of dolomite and calcite. Yzerfontein and Zwartwater North pans contain small aragonitic gastropod shells (Tomichia ventricosa) which are no longer active in the pans due to the high present-day salinities of the pan waters. Low-magnesian calcite is likely the first evaporite mineral to precipitate in the pans because of its low solubility.

Grantor dc:publisher.institution

Department of Geological Sciences

Year dc:date.issued

2009

Author dc:creator

• Mauger, Carla

Advisors dc:contributor.advisor

• Compton, John
• Roychoudhury, Alakendra N

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/11427/9240

OAI identifier oai:identifier

oai:open.uct.ac.za:11427/9240