查看更多>>摘要：A grain of unexpected mineral composed of FeO (wiistite) and SiO2 (quartz) with au intergrowth structure was found in ophiolitic chromitite, Luobusa, Tibet. According to high-pressure and temperature experimental studies, this intergrowth broke down from a silicate mineral (perovskite?),suggesting that it is possibly found in mantle depth of more than 670 km.
查看更多>>摘要：The Maksyutov complex is a part of Precambrian folded belt extending from Urals, North Karakum, Kunlun, Qilian, Qinling to the Dabie-Sulu belt of eastern China. In Maksyutov the eclogites present as individual blocks and boudines embedded within the glaucophane and micaceous schists. Due to the Phanerozoic multi-phase granite intrusions and their resulting superposed metamorphism the data on the age of eclogite are diverse spanning from Early Proterozoic to lower Paleozoic. The mineral compositions of the eclogite are constant with garnet, omphacite and rutile; however, they are often replaced by metamorphic assemblages of epidote-blueschist facies. The garnets are iron rich with f=50-75% (f = Fe2+/(Mg + Fe2+)). Clinopyroxenes are omphacites with Jd 40.3-52.2. According to the garnet clinopyroxene geothermometry and Jadeite + quartz→albite geobarometry T=1060-686 °C, P=2.23-1.416GPa are estimated. The PT trajectory of Maksyutov eclogite corresponds to the upward intrusion of eclogite magma, the final consolidation of the eclogites probably took place in the lower crust.
查看更多>>摘要：According to the comprehensive study of the depositional sequence of the outcrop sections from Cretaceous to Tertiary of the Tarim Basin, and the analyses of the seismic sequence and drilling data,the strata of Cretaceous-Tertiary of the Tarim Basin can be subdivided into 30 3rd-order depositional sequences in the southwestern depression and 22 3rd-order dpositional sequences in the northwestern depression. This indicates that the 3rd-order sequences can not be correlated directly one by one because of their different tectonic settings and sedimentary environments. Whereas, based on the study of 2nd-order supersequence, the strata from Cretaceous to Tertiary can be divided into 4 supersequences and correlated isochronously in these two areas of the Tarim Basin.
查看更多>>摘要：Through a review of the history of the study of the uplift of the Qinghai-Tibet Plateau and an analysis of various dynamic models of the uplift and on the basis of the strong inhomogeneity of the lithospheric structure of the Qinghai-Tibet Plateau and "tripartite" and "symmetric" structural geomorphologic pattern, the authors propose that the uplift of the Qinghai-Tibet Plateau is the result of integrated action of bidirectional differential subduction of the Indian block and the Tarim-Alxa block and the deep-seated thermal-uplift spreading beneath the interior of the Qinghai-Tibet Plateau.Subduction is an important mechanism of the uplift and thermal-uplift spreading is the direct cause.
查看更多>>摘要：There are large-areas of late Yanshanian granites in the Dabie Orogen, but the formation mode of the relevant granitic magma is still under discussion. Taking the typical Yanshanian granites in the North Dabie Block The TG and JG as examples, the Writers endeavor to discuss contain aspects of the formation mode of the granitic magma by studying the characteristics of the chemical compositions of biotite and amphibole of the granites and petrological features of enclaves in the intrusions, in the light of recent results of experimental petrology on dehydration melting and aquifer melting. It is suggested that: (1) Some biotites in the Tiantangzhai and the JGs and their enclaves were residual minerals; (2) Some of the amphiboles could be new-born minerals, and others, residual ones.(3) the banded bodies in granites were residuals of anatexis. (4) The TG and JG were formed by aquifer melting, and the South Dabie Block could be the important source region of water.
查看更多>>摘要：There is a distinct zone of A-type granite in western Kunlun Mts. with the scope corresponding to the Kudi mantle steps. The A-type granites generated in late Indosinian, intergrowthing with late Hercynian I-type granites. The characteristics of A-type granitic rocks are enrichment in alkali, LREE,Y, Nb, Zr, lean in Al, Mg, Ca, Ba and Sr transition elements, and extended SiO2 contents, which are quite similar to those of A-type granite in Chaelundi, Australia. The research results indicate that the studied granites belong to A2-type which formed in late orogenic extension environment and intruded in the process of the lithospheric delamination.
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