Thursday, March 12, 2015

Highlights—Abiotic Needle-Fiber Calcite

Needle-fiber calcite (NFC) is common diagenetic cement that has been found globally in many different types of limestone. The origin of NFC has been widely debated, and both abiogenic and biogenic processes have been invoked to explain its origin. In recent years, the origin of NFC has been closely allied to fungi. Jones and Peng document NFC in the spring deposit at Shiqiang, Yunnan Province, China, where NFC is common—but never associated with fungi. The study explores the different possible mechanisms and concludes that these NFC formed by abiogenic processes, driven largely by evaporation. These results highlight the critical problems in trying to ascertain the origin of carbonate cements, and the dangers of trying to ascribe all NFC to biogenic processes.

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