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Clay Mineral Distribution in a Modern Sedimentary System, Surface Sediments from Ravenglass Estuary and beyond

Daneshvar, Ehsan *1; Worden, Richard H.1; Hodgson, Dave 1
(1) Earth & Ocean Sciences, Univ Liverpool, Liverpool, United Kingdom.

Ravenglass estuary in North West England is a trap for the transported and in situ clay minerals. A clay mineral study from hinterland geology (granite and Triassic Sandstones) toward estuarine surface sediments has been undertaken using X-ray diffraction (XRD), fourier transform infra red (FTIR) and scanning electron microscopy (SEM/BSE/EDAX) techniques. Samples from (1) fluvial sediments beyond the high tide line, (2) surface sediments at the upper part of the estuary and (3) lower part of the estuary in respect of the clay minerals, have been analysed. Discrimination of the clay minerals using XRD in association with glycolataion salvage and heating treatment to identify the behaviour of 7Å and 14Å peaks have been discussed and concluded that chlorite from hinterland toward the estuary is being changed in quantity and quality from dioctahedral abundant in fluvial sediments to tetrahedral Fe-rich chlorite in surface estuarine sediments. Chlorite, illite and kaolinite and possibly berthierine are all present in surface sediment in the estuary. Chlorite, a minor expandable phase such as hydroxyl-interlayer vermiculite (HIV), dioctahedral chlorite and also illite are present in the fluvial sediments, beyond the tidal reach. Given the abundance of kaolinite and illite within the estuarine sediments in comparison to the fluvial sediment, it seems likely that these minerals were formed within the estuarine environment. Sand grains in the estuarine surface sediments are coated with a fine layer of clay minerals including chlorite, illite, mix of illite-chlorite, Fe-rich chlorite, berthierine and kaolinite.

 

AAPG Search and Discovery Article #90142 © 2012 AAPG Annual Convention and Exhibition, April 22-25, 2012, Long Beach, California