2009 Portland GSA Annual Meeting (18-21 October 2009)

Paper No. 23
Presentation Time: 9:00 AM-6:00 PM


BELDING, Elyssa1, WILSON, Mark A.2, SHARPE, Meredith2, BOWEN, Jeff2 and LEHMANN, Sophie3, (1)School of Earth Sciences, Ohio State University, 275 Mendenhall Laboratory, 125 South Oval Mall, Columbus, OH 43210, (2)Department of Geology, The College of Wooster, 1189 Beall Ave, Wooster, OH 44691, (3)Geology, Miami University, Shideler Hall, Oxford, OH 45056, ebelding09@wooster.edu

The Matmor Formation (Callovian, Middle Jurassic) of southern Israel is an excellent record of a Jurassic equatorial shallow marine paleoenvironment. It is exposed in Hamakhtesh Hagadol, an erosional cirque (makhtesh) located in the northern Negev Desert. The fossil and rock samples collected for this study were from multiple sections at the northern and western edges of the makhtesh. The Matmor Formation is distinguished by its abundance and diversity of well-preserved fossils such as bivalves, gastropods, sponges, corals, echinoderms, brachiopods, and various sclerozoans. The preservation of the body fossils ranges from original and recrystallized hard parts to internal and external molds. This work is the culmination of several studies conducted in the Matmor Formation by College of Wooster students and is the first to combine all the paleontological, sedimentological and stratigraphic data into one report. There are six phyla, ten classes, twenty-four orders, fifty-eight genera, and fifty-seven species now described from the Matmor, as well as numerous unknown sponges and corals. Three paleocommunities are present: the Diverse Echinoderm Community, a set of Sponge-Coral Reefs, and the Diverse Mollusk Community. The Diverse Echinoderm Community contains the highest abundance and diversity of echinoderms (crinoids and echinoids). The environment for this assemblage was a relatively low energy environment below wavebase within the photic zone, which experienced pulses of elevated sedimentation. The Sponge-Coral Reefs were patches of calcified demosponges and microsolenid corals with many borings and encrusters (sclerozoans). These reefs were in very shallow water (just below low tide in many cases). The Diverse Mollusk Community contains the highest abundance and diversity of bivalves and gastropods and lived in a shallow water environment that was above wavebase. The Matmor Formation shows a series of shallowing-upwards sequences with the fossils most often preserved during transgressions. The body fossil communities show an overall diversity comparable to similar communities in higher latitudes in Europe and elsewhere. Trace fossils, especially those from bioerosion, are relatively low in diversity. Normal faulting is present throughout the Matmor Formation and could be associated with rifting.