A review of the geology of the dolomite-dominated carbonatite complexes of the Kalahari Craton, southern Africa

✍ Scribed by R.E. Harmer

• Book ID: 104354080
• Publisher: Elsevier Science
• Year: 2001
• Tongue: English
• Weight: 242 KB
• Volume: 32
• Category: Article
• ISSN: 1464-343X
• DOI: 10.1016/s0899-5362(01)90037-5

✦ Synopsis

Yb ratios ranging from 25 to 345 exhibit notable increase from sijvite to ankeritic carbonatite. The calcite-carbonatite (sijvites) from the ring-dyke show variable stable isotope ratios ranging from 613C=-3.77 to -5.11 and 6180 = + 9.2 to + 11.6%0. The ankeritic carbonatite, which occurs as a plug in the sijvite ring-dyke, on the other hand, reveals higher 0 isotopic ratios up to 6'*0 of 12.00%0. Thus, within a given carbonatite complex, the isotope ratios increase from sijvite to ankeritic carbonatite. The negative values obtained for these rocks shift down to 613C=-3.77%0. The high 6180 values (up to + 19.4%0) of the slivite samples from the sill-like intrusion in the Siriwasan-Dugdha sector (north of Ambadungar) may be attributed largely to late stage evolution and hydrothermal/ meteoric alteration.