| 藏南红旗区高温橄榄岩体及铬铁矿体特征的初步研究 |
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| A PRELIMINARY STUDY ON THE FEATURES OF HIGH TEMPERATURE PERIDOTITE AND THE OCCURRENCES OF CHROMITE DEPOSIT IN HONGQI DISTRICT SOUTH XIZANG (TIBET), CHINA |
| Though there were many papers dealing with the characteristics ofthe chromite deposits in Southern Xizang (Tibet), the dominant featurese.g., the lateral plunging and bending of the ore bodies in three dimensions were not touched. From the evident plunging feature of the ore bodiesas deduced by means of comparative study of the drilling cores and whatwas actually seen on the surface, the writer suggests that it may be comparable to that of Xilin Gol Meng (Nei Monggol) and Robrova (Yugoslavia).This characteristic feature shouldn't be neglected because it is valuablefor correct evaluating and prospecting of the deposits. The bending ofthe ore bodies in chromite deposits has not been described before eitherand may be comparable to that of Brucheze deposit of Albania. Concerning the emplacement of the ultramafic bodies of SouthernXizang there are three alternative assumptions: 1. This peridotite body near Yarlung Zangbo River was formed by the intrusion of ultramafic magma to the eugeosyncline of Himalayaalong the deep seated fractures. 2. It was emplaced as the result of the Pamir-Himalaya "η" typetectonism. 3. It is a part of the ophiolite suites situated along the suture zoneof the Eurasian and Indian plates during their collision. Some geologists have suggested that the ophiolite belt was a marginal oceanic basinand others suggested that it was the relics of Tethys oceanic crust. Based on the study of the age of the emplacement of the peridotite,its occurrence in the supposed sequences of the ophiolite suites, its petrochemical features and the freshness of its rock-forming mineralsnearly without any alteration and the presence of high grade metamorphic minerals surrounding this peridotite, the writer suggests thatthis peridotite should be a high temperature one rather than that formed under other conditions. The contact metamorphic minerals found aregarnet (grossularite), diopside, vesuveanite, white ilmenite and a littleamount of epidote, magnetite, sphene, etc. She also suggests that thisperidotite has come from the upper mantle as a hot ultramafic magmadiapiric form under conditions of tectonic deformation. Such conditionsmay be comparable to those of Lizard (UK) and Tinaquillo (Venezuela).And in this respect this high temperature peridotite is dissimilar to theophiolite of the ophiolite suite. Although the phenomenon of contact metamorphism of this peridotite body was first noticed in 1960 anddescribed in many papers since then, not until 1980 the writer suggestedthe term "high temperature peridotite" for this intrusion. |
| WANG Ruo-hua.1983.A PRELIMINARY STUDY ON THE FEATURES OF HIGH TEMPERATURE PERIDOTITE AND THE OCCURRENCES OF CHROMITE DEPOSIT IN HONGQI DISTRICT SOUTH XIZANG (TIBET), CHINA[J].Acta Geoscientica Sinica,5(1):37-48. |
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