Geological and geochemical data from the proposed Sirente crater field: New age dating and evidence for heating of target

Abstract

The proposed Sirente crater field consists of a slightly oblong main structure (main crater) 120 m in width and about 30 smaller structures (satellite craters), all in unconsolidated but stiff carbonate mud. Here we focus on the subsurface structure of the satellite craters and compare the Sirente field with known meteorite crater fields. We present a more complete outline of the crater field than previously reported, information on the subsurface morphology of a satellite crater (C8) 8 m in width, radiocarbon and thermoluminescence (TL) ages of material from this crater, and evidence for heated material in both crater C8 and the rim of the main crater. Crater C8 has a funnel shape terminating downwards, and evidence for soil injection from the surface to a depth of 9 m. The infill contained dispersed charcoal and small, irregular, porous fragments of heated clay with a calibrated age of B.P. 1712 (13C-corrected radiocarbon age: B.P. 1800+/-100) and a TL age of B.P. 1825 (calculated error +/-274). Together with previous radiocarbon age (B.P. 1538) of the formation of the main crater (i.e., target surface below rim), a formation is suggested at the beginning of the first millennium A.D. Although projectile vaporization is not expected in Sirente-sized craters in this type of target material, we used geochemistry in an attempt to detect a meteoritic component. The results gave no unequivocal evidence of meteoritic material. Nevertheless, the outline of the crater field, evidence of heated material within the craters, and subsurface structure are comparable with known meteorite crater fields.