郯庐断裂带张八岭隆起北段晚中生代岩体的成因

郯庐断裂带张八岭隆起北段分布着一些晚中生代岩体,其侵位时间在120~128 Ma之间,稍晚于同期华北克拉通内江苏徐州和安徽宿州地区(简称徐宿地区)。文章通过对上述两地区的地球化学特征的对比研究,认为张八岭隆起北段岩体的岩浆来源可能是壳-幔岩浆混合形成的,并可能经历了一定的岩浆分异作用;而徐宿地区岩浆可能与深部地壳物质的部分熔融有关。上述结果表明,张八岭隆起北段岩浆来源深度较华北克拉通内部徐宿地区深,断裂带内具有较强的伸展活动及岩石圈减薄程度。分析认为,断裂带的存在和活动在岩石圈减薄过程中具有诱发和促进作用。

Discussion of petrogenesis on late mesozoic intrusions from the northern segment of Zhangbaling uplift belt along the Tan-Lu fault

Emplacement ages(120～128 Ma) of the late Mesozoic intrusions from the northern segment of Zhangbaling uplift belt along the Tan-Lu fault are later than Mesozoic intrusive complex in the Xuzhou-Suzhou areas. Based on their geochemical characteristics, Zhangbaling intrusions imply that magma sources should be a mixing of melting between the crust and the mantle, and experienced a certain extent crystallization. However, the intrusive complex in the Xuzhou-Suzhou areas mostly derived from the partial melting of the lower crust. Investigations indicate that the depth of magmatic origin in Zhangbaling uplift belt was deeper than the Xuzhou-Suzhou areas compared with inner North China Craton. The Tan-Lu fault zone had intensive extensive activities and lithosphere thinning degree. Therefore, the occurrence and activities of the fault zone played an inducing and promoting role in magmatic activities during lithosphere thinning.