Structural Stability of Natural Magnesiochromite at High-Temperature-Pressure Conditions  

作　　者：Shuyu Jin Xiang Wu Yungui Liu Yanfei Zhang Chao Wang 

机构地区：[1]State Key Laboratory of Geological Processes and Mineral Resources,China University of Geosciences,Wuhan,430074,China [2]College of Gems and Materials,Hebei GEO University,Shijiazhuang,050031,China

出　　处：《Journal of Earth Science》2024年第4期1196-1203,共8页地球科学学刊（英文版）

基　　金：supported by the National Science Foundation of China(No.41827802);performed at GeoSoilEnviroCARS(Sector 13-ID-D);Advanced Photon Source(APS),Argonne National Laboratory(ANL);supported by the National Science Foundation-Earth Sciences(No.EAR-1634415);the Department of Energy,Geosciences(No.DE-FG02-94ER14466);APS is supported by DOE-BES(No.DE-AC02-06CH11357).

摘　　要：The podiform chromitites in the Luobusha ophiolite have been thought to experience a very deep formation,but the maximum depth is still an open issue.Here,we have investigated the structural stability of natural magnesiochromite using the synchrotron-based powder X-ray diffraction and diamond anvil cells up to 48.6 GPa and 2450 K.The results have shown that spinel-type magnesiochromite first decomposes into corundum-type‘Cr_(2)O_(3)’+B1-type‘MgO’at 11–14 GPa and 1250–1450 K,then modified ludwigite(mLd)-type‘Mg_(2)Cr_(2)O_(5)’+corundum-type‘Cr_(2)O_(3)’at 14.3–20.5 GPa and 1300–2000 K,and finally CaTi_(2)O_(4)-type phase at 24.5 GPa.During the quenching procession from high-temperature-pressure conditions,the mLd-type phase appeared again and was kept at ambient conditions.We also obtained the isothermal equation states of spinel-type and CaTi_(2)O_(4)-type phases,revealing the composition effect on their elasticities.Based on the updated results,we propose chromitites could not experience pressure exceeding∼14.3 GPa(approximate maximum depth∼400 km)in the subduction-recycling genesis model.

关 键 词：CHROMITE high-temperature and high-pressure phase transitions equation of state chromitites genesis 

分 类 号：P618.31[天文地球—矿床学] P618.33[天文地球—地质学]