论文部分内容阅读
太平-黄山复合岩体是个由钙碱性(太平岩体)向碱性(黄山岩体)转变的独特杂岩体,且其中黄山岩体的稀土元素分馏模式表现出罕见的“四素组效应”(tetrad effect),代表高度演化的末期岩浆组分.该复合岩体提供了研究扬子克拉通东南部晚中生代构造环境的变迁及岩石圈减薄的难得机会.文中测得太平花岗闪长岩的锆石U-PbSHRIMP年龄为(140.6±1.2)Ma.4个采自黄山岩体不同期次或不同相带样品的锆石U-PbSHRIMP年龄分别为(127.7±1.3),(125.7±1.4),(125.1±1.5)和(125.2±5.5)Ma,这几组年龄数据在误差范围内近于一致,说明黄山岩体是在很短的时间内侵位的.虽然太平岩体和黄山岩体在空间上紧密共生,但它们之间侵位的时间间隔长达15Ma左右,岩浆性质由钙碱性突变到碱性,中间缺少明显的过渡环节,所指示的可能是扬子克拉通东南部中生代的岩石圈减薄事件,该事件发生在约141～128Ma之间,减薄机制应以机械拆沉为主.
The Taiping-Huangshan composite rock mass is a unique complex rock body transformed from calc-alkaline (Taiping rock mass) to alkaline (Huangshan rock mass), and the rare earth element fractionation model of Huangshan rock mass shows a rare “ Tetrad effect, ”representing the highly evolved, late magmatic component, provides a unique opportunity to study the late Mesozoic tectonic setting and lithospheric thinning in the southeast of the Yangtze craton. The zircon U-Pb SHRIMP ages of the diorites are (140.6 ± 1.2) Ma. The zircon U-Pb SHRIMP ages of the four samples collected from different or different phases of the Huangshan pluton are (127.7 ± 1.3), (125.7 ± 1.4), (125.1 ± 1.5) and (125.2 ± 5.5) Ma, respectively, which are close to the same within the error range, indicating that the Huangshan pluton emplaced in a very short period of time. The Huangshan rock mass is closely intergrowth in space, but the emplacement time between them is about 15Ma. The magmatic property changes from Ca-Al to Alkaline, with no apparent transitional link in the middle. The indicated may be southeastern Yangtze craton Department of Mesozoic lithospheric thinning event, the event occurred in about 141 ~ 128Ma, minus Mechanism should be based on mechanical delamination.