Las perforaciones del ODP=leg 161 en el Mediterráneo Occidental

Abstract

Leg 767 drilled a transect of six sites in the Western Mediterranean. Sites 974 (Tyrrhenian Basin) and 975 (Menorca Rise, South-Balearic Basin) were dedicated to paleoceanography and Sites 976, 977, 978, 979 (Alboran Basin) focused on tectonic goals but also involved paleoceanographic studies. A total length of 3.9 km of sediment and rock cores were collected from nearly 7 kilometer below the sea floor. One of the most Intriguing paleoceanographic results of Leg 767 was the discovery of sapropels in the Western Mediterranean. Pleistocene sapropels were recovered at Site 974 and Site 975, and Pleistocene organic-rich layers at Sites 976, 977, and 979. Site 976 cored 258.97 m of high-grade metamorphic rocks down into the basement, and demonstrates that the basement beneath the Alboran Sea is formed by rocks of continental origin that have undergone exhumation and decompression. Sites 977, 978 and 979 cored through a zone of structures within the sedimentary sequence, yielded information on the compressive post-Messinian tectonic reorganization of the Alboran basin