Progress Report on Dolomitization — Hydrology of Abu Dhabi Sabkhas, Arabian Gulf
The authors evaluate the dolomitizing potential of three hydrologic systems — “seepage reflux” (Adams & Rhodes, 1960), capillary action (Friedman & Sanders, 1967), and “evaporative pumping” (Hsü & Siegenthaler, 1969). Laboratory experiments demonstrate the efficiency of the latter process as a potential mechanism of water flow necessary for dolomitization, and show that this flow is not due to capillary forces but to reduction in pore pressure due to evaporation of interstitial vapour.
In an attempt to confirm the validity of laboratory experiments a series of pits was excavated across the sabkha SE of Abu Dhabi Island where manometers were inserted into various horizons within the sabkha. Field experiments were complicated by the fluctuation of both sea level (due to tides) and water level within the sabkha. This did not prevent the discovery of local hydraulic gradients oriented vertically upwards, confirming the validity of the evaporative pumping model. Manometric measurement made on horizons below an impermeable limestone crust within the sabkha suggest that continental groundwater is the source for evaporative pumping, although seawater cannot be excluded as a source for the more coastal parts of the sabkha.
KeywordsPermeability Magnesium Depression Petroleum Sandstone
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