| 北秦岭中生代沙河湾岩体环斑结构特征及有关问题的讨论 |
| 修订日期：2001-07-18 |
| 关键词:rapakivi texture Shahewan pluton Qinling orogen |
| 基金项目:国家自然科学基金(40072065)，中国地质调查局重点基础地质研究项目“中国花岗岩重大地质问题研究”和西北大学大陆动力学教育部重点实验室开放基金 |
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| Characteristics of Rapakivi Texture in Mesozoic Shahewan Granite of North Qinling Mountains and Some Related Problems |
| Rapakivi texture of the Shahewan pluton mainly occurs in megacryst bearing biotite horblende quartz monzonite. Rapakivi feldspars are mostly about 2 cm×4 cm in size and enhedral in shape, with some assuming ovoid form. A rapakivi feldspar grain consists of alkali feldspar core and plagioclase mantle. The core is generally composed of a single alkali feldspar grain characterized by Or 95～84, Karlsbad twin and perthitic texture. The plagioclase mantle is oligoclase with An=20±. Both the core and the mantle have inclusions of biotite, hornblende, quartz and plagioclase. The quartz inclusion in alkali feldspar megacrysts is concave and drop like in shape. The major minerals of the Shahewan pluton have two generations. Their textures are comparable with those of the typical rapakivi granites. This suggests that the typical rapakivi texture can be formed in various epochs and different tectonic settings. As the age and tectonic setting of the Shahewan pluton obviously differ from those of typical rapakivi granites, whether the granite belongs to rapakivi granite or a new type of granites needs further investigation. |
| WANG Xiao-xia,WANG Tao,LU Xin-xiang.2002.Characteristics of Rapakivi Texture in Mesozoic Shahewan Granite of North Qinling Mountains and Some Related Problems[J].Acta Geoscientica Sinica,23(1):30-36. |
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