| 北秦岭丹凤群向西延入祁连造山带的地质意义 |
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| 基金项目:地质科学技术行业基金资助项目（编号88018） |
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| THE WESTWARD EXTENTION OF THE EARLY PALEOZOIC DANFENG GROUP INTO THE QILIAN OROGEN AND ITS GEOLOGICAL SIGNIFICANCE |
| Rescently, the Danfeng Group and its ophiolite belt in the eastern portion of the North Qinling area has been further studied, though many researchers have corroborated it as a south ophiolite belt of the Qinling Range. It has been confirmed in this investigation that the portion from Baijiadian in Fengxian, Shaanxi to Gaojiahe in Longxi, Gansu is a continuously west-extending volcanic and ultramafic rock belt. In the portion from Guanzizhen in Tianshui County to Gaojiahe in Longxi County, apart from the volcanic rocks, there concentratedly emerge ultramafic rocks especially the Yuanyangzhen ultramafic rock body in Wushan County, Gansu, which is the largest in the eastern portion of the Qilian Mountains. According to the fact that the volcanic rocks of the area are characteristic of an island-arc association and that the ultramafic rock bodies occur mainly along fracture or secondary fracture systems, it is considered that the rock belt is made of melting ultramafic rocks derived from an island-arc root or the Earth's mantle by compressive stress and extrusion along fracture system, during a collision of the South and North China plates. Geologic data from Gansu and Qinghai Provinces show that the western portion of the Danfeng ophiolite belt extends westward through a large loess cover and reappears at the Wushushan, Gansu and the Lajishan, Qinghai and also consists of volcanic and ultramafic rocks of the Early Palaeozoic age. The westward extension of the ophiolite belt implies. It has that the North Qilian orogen has the same structural framework as the North Qinling Caledonian foldbelt and that they belong to the same orogen on the southern margin of the North China plate. |
| SONG Zhi-gao.1993.THE WESTWARD EXTENTION OF THE EARLY PALEOZOIC DANFENG GROUP INTO THE QILIAN OROGEN AND ITS GEOLOGICAL SIGNIFICANCE[J].Acta Geoscientica Sinica,14(2):15-26. |
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