%0 Journal Article %T 浙西开化地区新元古代（～828 Ma）弧后盆地扩张——来自类复理石和辉绿岩墙的年代学和地球化学证据<br>Neoproterozoic (~828 Ma) Expansion of Back-Arc Basin: Implications fromGeochronology and Geochemistry of the Diabase and Flyschoids in Kaihua %A 唐增才 %A 陈忠大 %A 胡开明 %A 周汉文 %A 吴小勇 %A 董学发 %A 赵旭东 %A 余盛强< %A br> %A Tang Zengcai %A Chen Zhongda %A Hu Kaiming %A Zhou Hanwen %A Wu Xiaoyong %A Dong Xuefa %A Zhao Xudong %A Yu Shengqiang %J 地球科学(中国地质大学学报) %D 2018 %R 10.3799/dqkx.2018.572 %X 浙西开化地区处于江南造山带东段，新元古代骆家门组类复理石建造沿苏庄－石柱断裂两侧分布，南东侧解元岭地区侵入有一组辉绿岩墙群，北西侧杨岭地区发现沉凝灰岩夹层.定年结果显示，杨岭地区沉凝灰岩LA-ICP-MS锆石U-Pb年龄为(830.9±4.9) Ma，解元岭辉绿岩SHRIMP锆石U-Pb年龄数据限定其成岩年龄下限为(828.2±8.7) Ma.辉绿岩以高Al2O3(15.82%～17.09%)，低TiO2(0.64%～1.37%)，贫K2O(0.01%～0.04%)为特征，具有平坦的稀土配分型式，(La/Yb)N=1.02～1.78，(Ce/Yb)N=0.93～1.72，与MORB和BABB类似，而大离子亲石元素Sr、Ba、Th、Pb的富集，Nb/U=11.67～28.17，La/Nb=1.21～2.02，Th/Ta=1.79～2.86，则表明岩石形成过程中遭受了弱的地壳物质的混染，显示其更可能是古华南洋向北西扬子陆块俯冲消减诱发弧后小洋盆扩张的产物，同时暗示双溪坞弧可能系裂离弧，更进一步表明华夏陆块与扬子陆块在新元古代(～828 Ma或更晚)尚未完成碰撞拼贴.<br>As a record of the process for expansion of the back-arc basin, the Xieyuanling diabase dyke swarms and the Yangling tuffs found interlayer in the flyschoids of Luojiamen Formation along the two sides of the Suzhuang-Shizhu fault in Kaihua area, western Zhejiang, and which is the eastern segment of Jiangnan orogeny. The U-Pb dating of zircon yields a lower limit age of 828.2±8.7 Ma for the Xieyuanling diabase,and another age of 830.9±4.9 Ma for the Yangling tuffs. Geochemical analysis indicates that the diabases have high Al2O3 (15.82%–17.09%), low TiO2 (0.64%–1.37%) and poor K2O (0.01%–0.04%). In the chondrite- and primitive mantle-normalized trace element diagram, all diabase samples show flat patterns,with (La/Yb)N=1.02–1.78 and (Ce/Yb)N=0.93–1.72, shows the similar characteristics of MORB or BABB. And they also enriched in Sr, Ba, Th and Pb, with Nb/U=11.67–28.17, La/Nb=1.21–2.02, Th/Ta=1.79–2.86, that indicate the formation process of diabase must have been contaminated by weak crustal materials. Therefore, a spreading of back-arc basin occurred with the paleo-South-China plate northwestwardly subducted in Neoproterozoic, it suggested the Shuangxiwu island arc rifted from the Yangtze block simultaneously, and the Yangtze block had not collided with the Cathaysia block at least at ca. 828 Ma or later %K 辉绿岩墙 %K 类复理石 %K 锆石U-Pb年龄 %K 地球化学 %K 新元古代 %K 浙西 %K 岩石学.< %K br> %K diabase dikeswarms %K flyschoids %K U-Pb dating of zircon %K geochemistry %K neoproterozoic %K western Zhejiang %K petrology. %U http://www.earth-science.net/WebPage/Article.aspx?id=4083