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Deciphering carbonates through the lens of multiple pathways to mineral formation

Patricia Dove, Virginia Tech

2010 F. Earl Ingerson Lecture
GSA Annual Meeting
Colorado Convention Center
Wednesday 3 November 2010 - 8:00a

Abstract

The impact of environmental change on biological and inorganic calcification processes is a forefront issue for understanding past and future earth environments. Efforts to decipher paleoenvironmental signals from biogenic and sedimentary deposits are dependent upon interpreting conditions at the time of mineralization while the community is also calling for an understanding of how calcifying marine organisms will respond to increasingly acidified oceans. Both lines of inquiry are now faced with the realization that long-standing 'principles' of calcification are undergoing a remarkable shift away from the paradigm that composition signals must be interpreted within the concepts of classical crystal growth. Overwhelming evidence from structural biology shows that most carbonate-producing organisms form skeletons by nonclassical growth processes. That is, most biogenic calcification begins with the accumulation and storage of an amorphous phase that transforms to a composite of mesocrystals. This emergent idea calls for a critical course correction because: 1) hundreds of studies are founded on the assumption that skeleton formation is governed by principles of classical crystal growth; and 2) early work is showing this new (but very old) nucleation-dominated process obeys a different set of dependencies upon chemical and environmental conditions from those established for classical growth. The presentation will highlight findings from our efforts to determine factors that bias a mineralization process toward a mesocrystal pathway and the consequences of this pathway for Mg levels in carbonate biominerals and sedimentary deposits.