Clinopyroxenes as petrogenetic indicators in Egyptian Proterozoic rocks
Basta, F. F.; Hafez, A. M. A.
Neues Jahrbuch für Mineralogie - Abhandlungen Band 153 Heft 1 (1985), p. 77 - 90
15 references
published: Dec 6, 1985
ArtNo. ESP154015301005, Price: 29.00 €
Abstract
Microprobe analyses of relict clinopyroxenes in Proterozoic mafic and ultramafic rocks from the southern central part of the Eastern Desert of Egypt are presented and discussed. Samples were seleced from the Ghadir ophiolitic (wehrlite and sheeted diabases) and non-ophiolitic rocks (the Muhagara volcanic breccias and Sabahia pyroclastics). The clinopyroxenes in the wehrlite and sheeted diabases are chrome-diopsides and endiopsides, respectively. The clinopyroxenes in the Muhagara volcanic breccias and Sabahia pyroclastics are titanaugites and augites, respectively. Comparison of the compositional data of clinopyroxenes in the Egyptian rocks with that of modern analogues suggests that the tectonic settings of the wehrlite, sheeted diabases and Sabahia pyroclastics are most consistent with a mid-ocean ridge, marginal basin or island arc; whereas that of the Muhagara volcanic breccias is consistent with that of within-plate alkali basalt. The last type of clinopyroxenes is presented and discussed here for the first time in Egypt.
Keywords
Clinopyroxene • microprobe analysis • mafic rock • ultramafic rock • Proterozoic petrogenetic indicator • Egypt