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引用本文:王 磊 龙文国 周 岱. 云开地区加里东期花岗岩锆石U-Pb年龄及其地质意义[J]. 中国地质, 2013, 40(4): 1016-1029.
WANG Lei, LONG Wen-guo, ZHOU Dai. Zircon LA-ICP-MS U-Pb age of Caledonian granites from Precambrian basement in Yunkai area and its geological implications[J]. Geology in China, 2013, 40(4): 1016-1029(in Chinese with English abstract).
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云开地区加里东期花岗岩锆石U-Pb年龄及其地质意义
王 磊 龙文国 周 岱
作者单位
王 磊 龙文国 周 岱 中国地质调查局武汉地质矿产研究所湖北 武汉 430223 
摘要:
提要:对云开地区1∶25万区调中划归前寒武纪或新元古代的(片麻状)花岗岩进行了锆石LA-ICP-MS U-Pb定年,获得的年龄分别为(443.3±2.6)Ma(样品1009,陆川县陆透水库东南)、(445.7±2.3)Ma(样品1010,陆川县月垌村)、(441.1±2.0) Ma(样品1012,高州市谢鸡镇)和(443.7±1.7)Ma(样品10108,信宜市朱砂镇),表明它们属于加里东期的产物而不是以往认为的前寒武纪基底或新元古代岩石。结合前人的研究表明,这些花岗岩主要由元古宙基底岩石发生深熔作用而成,是华南地区加里东期陆内造山作用的响应。随着云开地区前寒武纪基底中大量加里东期年龄的发现,说明加里东运动对该区的影响非常强烈,1∶25万区调中划归前寒武纪基底或新元古代的部分片麻状花岗岩应归属加里东期。云开地区前寒武纪基底主要是以片麻岩类为代表的高州杂岩和以变沉积岩类为代表的云开群,高州杂岩形成时代为中新元古代,云开群形成时代可能为新元古代。从整个华夏地块来看,存在古—中元古代结晶基底,但出露可能并不像以往认为的那么广泛。
关键词:  前寒武纪基底  花岗岩  加里东期  LA-ICP-MS  锆石U-Pb年龄  云开地区
DOI:
分类号:
基金项目:中国地质调查局基础地质综合研究项目“钦杭成矿带(西段)基础地质调查综合研究”(1212011085416)资助。
Zircon LA-ICP-MS U-Pb age of Caledonian granites from Precambrian basement in Yunkai area and its geological implications
WANG Lei, LONG Wen-guo, ZHOU Dai
Abstract:
Abstract:LA-ICP-MS U-Pb dating was conducted for zircons from four gneissic granites in Yunkai area, which were assigned to Precambrian basement rocks or Neoproterozoic intrusion in 1∶250000 geological survey. The dating yielded 206Pb/238U weighted mean of 443.3±2.6 Ma (sample 1009, Lutou Reservoir in Luchuan City), 445.7 ±2.3Ma (sample 1010, Yuedong in Luchuan city), 441.1±2.0Ma (sample 1012, Xieji in Gaozhou city) and 443.7±1.7Ma (sample 1018, Zhusha in Xinyi city), suggesting that these rocks are Caledonian products rather than Precambrian basement or Neoproterozoic intrusive rocks. In combination with previous studies, the authors hold that these granites probably resulted from partial melting of the Proterozoic materials due to the Caledonian orogeny in South China. These results and recently published data (Caledonian) for the so-called Precambrian basement rocks, such as the crystallization age or metamorphic age of gneissic granite and gneiss, indicate that Yunkai area has undergone extensive reformation by the Caledonian orogeny. Actually, the Precambrian basement of Yunkai area mainly consists of gneissic rocks and meta-sedimentary rocks, which serve as the representative of the Gaozhou complex and the Yunkai Group, respectively. The Gaozhou complex was formed during the Meso- to Neo-proterozoic and the Yunkai Group might have been formed in the Neoproterozoic. The Paleo- to Meso-Proterozoic crystallized basement does exist in Cathaysia Block, however,which is not so widely distributed as previously thought.
Key words:  Precambrian basement  granite  Caledonian  LA-ICP-MS  zircon U-Pb age  Yunkai area