Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of HosséréDammougalré(Adamawa Plateau, Cameroon): Thermobarometric Implications

• 作者: Abdel Aziz Youpoungam Dagwa? Nguihdama Fadimatou Ngounouno Yamgouot Isaac Bertrand Gbambié Mbowou Isma?la Ngounouno Mama Ntoumbe
• 来源期刊: 地质学期刊(英文)
• 学科: 地球科学
• 关键词: WEHRLITE Adamawa PLATEAU Hosséré Dammougalré MINERAL Chemistry GEOTHERMOMETRY
• 年，卷（期）: 2017,（10）
• 页码范围: 1465-1477
• 页数: 13页
• 分类号: P5

摘要

Wehrlite samples (size: ~4 cm) hosted in basaltic lavas from the SW of Hosséré Dammougalré are located in the western Adamawa Plateau. Porphyritic and allotriomorphic texture characterize respectively host Basalt and wehrlite xenoliths. The phenocrysts of olivine (Fo68&minus;74), and Ti-magnetite are scattered in host basalt. Wehrlite xenoliths (~4 cm size) contain Cr-rich clinopyroxene (diopise-augite), olivine (Fo76&minus;88) and chromiferous spinel. Equilibrium temperatures calculated from Fe/Mg exchange reaction for olivine/spinel vary between 944&#176;C and 1102&#176;C. The wehrlite olivine crystals with low Fo (<90) indicate a re-equilibration of Fe-Mg in the host basalt at low temperatures. All the analyzed wehrlite clinopyroxenes have crystallized at high pressures as evidenced by the Alvi and Aliv contents. The studied spinel-bearing wehrlite xenoliths represent probably the residual portions of the upper mantle, which are an important source of information about lithospheric composition and thermal evolution beneath the Adamawa Plateau.