PALEOECOLOGY AND LITHOFACIES EVOLUTION OF THE EARNLEY SAND AND MARSH FARM FORMATIONS, ISLE OF WIGHT, ENGLAND

The Earnley Sand and Marsh Farm Formations are mid-Lutetian age units in the Bracklesham Group,Hampshire Basin, southern England. The Earnley Sand is a sandy clay formation with a high percentage of glauconite and varying marine faunas preserved within. It overlies the Marsh Farm formation, a primarily clay formation with lenses of sand. Both formations are uplifted with a heavily reworked contact. Determination of the paleoecology of 10 meters of the Earnley Sand and Marsh Farm formations permits evaluation of the existence of coastal upwelling of the type proposed by Mann and Lazier (1991). Litho-stratigraphical observations at 15 centimeter increments and spatial variability sampling at 50 centimeter increments were made for this study. Analysis of the last of the Earnley Sand for foraminiferal abundance and other environmental indicators, such as sea urchin spines, fish scales and corals, and mineralogical evidence reveals a decrease in population of benthic foraminifera , and a decrease of other faunal populations . The Marsh Farm formation is initially devoid of faunal material but a high quantity of gypsum is present, with larger crystals present at the base of the formation. No planktic foraminifera were found in the sequence. Secondarily, the project attempts to link the presence of turritellines, hypothesized cold-water indicators (Allmon), with the foraminiferal record, a more conventional cold-water indicator in certain situations. Results indicate however, that upwelling is unlikely in the transitional sequence from the Earnley Sand to Marsh Farm formations due to the lack of planktic foraminifera associated with nutrient blooms (Buzas pers. comm.). The connection of the turritelline gastropods with the benthic foraminifera is therefore as yet uncertain. However, the findings corroborate the theories of Plint (1983) regarding facies transition within the Bracklesham Group. Plint (1982) hypothesized a lagoonal Marsh Farm.