Precipitation and diagenesis of hot spring deposits/Evolution of carbonate successions on isolated oceanic islands

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My research program will focus on (1) factors that control calcite, aragonite, and opal-A precipitation, (2) the role that microbes play in the precipitation of aragonite, calcite, and opal-A, and (3) the origin of pervasively dolomitized successons. Research goals 1 and 2 will be achieved by the detailed study of hot spring/geyser deposits, whereas research goal 3 will be based on the Tertiary dolostones of the Cayman Islands with comparisons being made to the Devonian dolostones of Alberta and Precambrian dolostones from China. Hot Spring/Geyser Deposits: Over the next five years, attention will be focused on spring systems found in Yunnan Province in China. Tectonic activity in this area, related to the collision between the Indian and Eurasian plates, gives rise to numerous springs that are characterized by water temperatures up to 100°C, pH values between 2 and 9, and variable water compositions. As such they are ideal natural laboratories for assessing the factors that control mineral precipitation and the distribution of microbial mats. Information obtained from these springs will be integrated with data that I have already obtained from spring systems that I have studied in Iceland, New Zealand, the Kenyan Rift Valley, and western Canada. Although focused on spring systems, this research will focus on questions that are pertinent to all carbonate deposits – including, for example, the factors that control aragonite as opposed to calcite precipitation, the role that microbes play in precipitation, and the factors that control preservation of soft-bodied microbes. Evolution of Tertiary dolostones of the Cayman Islands: This research will focus on the origin of the dolostones that form most of the Bluff Group (Oligocene – Pliocene in age) with the view of explaining how pervasively dolomitized successions originate under the low temperature and low pressure regimes near the surface of the earth. This study has important implications for the origin of dolostones of all ages and, in particular, the manner in which they evolve to become excellent hydrocarbon reservoirs. Over the next five years hypotheses developed from the Cayman dolostones will be tested against the bitumen-bearing Devonian dolostones in the Grosmont Formation of east-central Alberta and Precambrian dolostones from China. By examining dolostones of different ages and from different geographic locations it should be possible to identify commonalities that may then lead to a better understanding of the dolomitization process.