黑龙江晨明地区两个晚三叠世岩体的地球化学特征及其意义

通过LA—ICP—MS锆石U—Pb测年及岩石化学分析,研究了黑龙江晨明地区跃进村岩体和云头砬子岩体的年代学、地球化学和形成环境。结果表明,跃进村岩体和云头砬子岩体的年龄分别为213±3 Ma和209±3 Ma,属于晚三叠世中期岩体。跃进村岩体岩性以石英二长岩为主,属于准铝质、钙碱性系列,轻稀土元素富集、重稀土元素略亏损,属于I型花岗岩。云头砬子岩体岩性以碱长花岗岩为主,属于准铝质、碱性系列,轻稀土元素富集、重稀土元素略亏损,属于A型花岗岩。两个岩体可能形成于海西—印支期造山带的造山隆起至后造山伸展环境的转换期。

Geochemical characteristics and tectonic significance of two Late Triassic plutons in Chenming area,Heilongjiang

Using zircon LA-ICP-MS dating and petrological geochemical methods，the authors study the geo-chronology，geochemical characteristics and tectonic setting of Yuejincun and Yuntoulazi plutons in Chenming area， Heilongjiang． The zircon LA-ICP-MS dating for Yuejincun and Yuntoulazi plutons are 213 ± 3 Ma and 209 ± 3 Ma，respectively，belonging to the middle of Late Triassic． The Yuejincun pluton is composed mainly of quartz monzonite，which belongs to aluminous，calc- alkaline series and I- type granites． Their ＲEE models are character- ized by enrichment in LＲEE and depletion in HＲEE． The Yuntoulazi pluton is composed mainly of alkali feldspar granite，which belongs to aluminous，alkaline series and A- type granites． Their ＲEE models are characterized by enrichment in LＲEE，LILE and depletion in HＲEE，HFSE． The characteristics indicate that these two plutons could have formed during the Hercynian to Indosinian period of transition from an orogenic setting to a post- colli- sional extension．