A DIELASMA COMMUNITY FROM THE TRIASSIC OF MAKHTESH RAMON, SOUTHERN ISRAEL

The cosmopolitan brachiopod Dielasma ranges from the Upper Mississippian through the Upper Triassic. In southern Israel a new Dielasma community is recognized from the Triassic Saharonim Formation, Ramon Crater. The shells represent a new species and are very strongly sulciplicated, a feature that seems to be more prevalent in the Mesozoic than the Paleozoic. The Saharonim Formation was deposited under normal, calm, relatively shallow marine conditions as part of the global transgression of the Early Ladinian sea. There is no evidence of evaporitic or dolomitic sediments. The complete absence of scouring within the carbonates or signs of channeling and ripple marks implies that most of the Fossiliferous Limestone Member from which the shells were collected was deposited at least beneath wave base (at a paleolatitude of within 10°N) and may have been deposited even at a depth of between 100 to 200 m. Faunal constituents of the Saharonim Formation include conodonts, ostracods, foraminiferans, bivalves, cephalopods, gastropods, echinoderms and vertebrate remains that belong to the Sephardic Province and are diagnostic of the Middle Triassic series of Israel. The faunal composition and shallow depositional environment of the strata studied are useful in correlating the Triassic rocks in the Negev with those in Europe, and helps differentiate the Sephardic Province from the Germanic Muschelkalk and the Alpine Tethyan faunas to the north.