Paper No. 278-2
Presentation Time: 8:15 AM
ATTEMPTS OF CARBONATE FACTORY TO RECOVER AS AN INDICATION TO HINTERLAND ARIDIZATION EVENTS IN THE EARLY AND EARLY MIDDLE TRIASSIC, IN MIXED CARBONATE/SILICICLASTIC SEDIMENTARY SYSTEM, SOUTHERN MARGINS OF THE TROPICAL TETHYAN SEAWAY
The fully marine E – early M Triassic sedimentary succession in Israel, southern margins of the tropical western Tethyan seaway, had been under mixed, disturbed and pyrite–rich carbonate and siliciclastic conditions. The succession, laying deep in the subsurface today, displaying a complex depositional interplay of distal siliciclastic influx, followed by short term carbonate dominant intervals rich with low diverse heterozoans remains and very small foraminifers, giant and normal ooids, and carbonate cemented crusts also. The carbonate intervals were breakouts in a continuous, barren, somewhat rich to dominant siliciclastic sequence. An exclusive outcrop in southern Israel, although related to the early Pelsonian (M. Triassic) age, considered here as an E. Triassic sedimentary system continuation. It linked the carbonate recovery effort to aridization event in the hinterland rather than to sea level rise; the aridization led to starved sedimentary conditions, basin-constrained oxygen-stressed environment that had intensified by dust storm supply, formed the barren autochthonous sequence that found to be rich with bedding concordant Planolites
-like burrows. The interspersed low diverse heterozoans beds were transported from the slop’s higher parts, revealed differential distributions of echinoids, mollusks and especially foraminifera (large Pilammina-Pilamminella
versus small Glomospirids( and lit some constraints on their distribution pattern and their tolerance to oxygen depletion.
The continuous siliciclastic dominant system indicates continuous humid climate during the P-T transition–Induan (including the Smithian); it went through hinterland drying during most of the Spathian, followed by short term of humid conditions redevelopment during the late Olenekian; hinterland drying during the latest Olenekian was followed by humid conditions on the Olenekian-Anisian transition, twice at the Pelsonian, and during the Illyrian. Insights from the symmetric and asymmetric correlation of the climate fluctuations in the hinterlands of the northern and southern margins of the western tropical Tethyan seaway may light up the possible effects of the ICTZ behavior pattern and to considered possible extra-tropical forces on the periodic climate variations.