Petrology, Mineralogy and Geochemistry of the Emeishan Continental Flood Basalts, SW China:Evidence

来源 :地质学报 | 被引量 : 0次 | 上传用户:wufj77
下载到本地 , 更方便阅读
声明 : 本文档内容版权归属内容提供方 , 如果您对本文有版权争议 , 可与客服联系进行内容授权或下架
论文部分内容阅读
Electronic microprobe analyses for olivine, clinopyroxene and Cr-spinel in picrites, which we have discovered recently in the Emeishan continental flood basalt province (ECFBP), show that the olivine is rich in Mg, and that Cr-spinel is rich in Cr. Based on the olivine-melt equilibrium, the primary parental melt compositions are calculated. The high-Mg olivine-hosted picrite can be regarded as parental melt. Thus, the melting temperature and pressure are estimated:T=1600℃ and P=4.5 GPa. It suggests that the picrites are connected with the activity of mantle plumes. Their major element composition is comparable to many other CFBs by their high Fe8, (CaO/Al2O3)8 and low Nas, indicating a high pressure. All rocks display a similar chondrite-normalized REE patterns, i.e., enrichment of LREE, relative depletion of HFSE and absence of negative Nb and Ta but depletion in P and K. Some incompatible element ratios, such as La/Ta, La/Sm, (La/Nb)pM, (Th/Ta)pM, are in a limited range, show that they were derived from the mantle plume, and there was no or little crustal contamination during magma ascent en route to the surface. They were generated by 7% partial melting of garnet peridotite. The axis of the plume might be located beneath Lijiang Town, Yunnan province.
其他文献
Source-contacting gas, which is also called basin-center gas, deep basin gas, is the tight-sand gas accumulation contacting closely to its source rocks. Having
Floodwater and debris flow caused by glacial lake burst is an important land process and a serious mountain disaster in glacial area of Xizang (Tibet) Autonomou
A genetic algorithm(GA)-based new method is designed to evaluate the circularity error of mechanical parts.The method uses the capability of nonlinear optimizat
Molecular phylogeny of three genera containing nine species and subspecies of the specialized schizothoracine fishes are investigated based on the complete nucl
Using the hydrographic data obtained from two sectional observations crossing the Luzon strait in the summer of 1994 and in the winter of 1998, the volume trans
The composition of gases trapped in olivine, orthopyroxene and clinopyroxene in lherzolite xenoliths collected from different locations in eastern China has bee
The Cretaceous system of the Kuqa depression is a regional scale (second order) depositional sequence defined by parallel unconformities or minor angular unconf
The Mianltüe suture extends from Demi-Nanping-Pipasi-Kangxian to the Lüeyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huasha