浙西北及江绍断裂带分别发现早古生代和晚古生代岩浆活动
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摘要
浙西北地区乃至浙赣皖相邻区早古生代受华南加里东构造活动的影响,仅发育轻微褶皱及断裂,造成上古生界与下伏前震旦系浅变质岩系—下古生界之间的区域性角度不整合,而不发育早古生代、晚古生代岩浆活动。在浙皖交界开化县获得445Ma±19Ma的岩浆岩LA-ICP-MS锆石U-Pb年龄,另在金华山后(江绍断裂带北侧)年龄为452.1Ma±2.7Ma的细粒花岗岩旁,发现了206Pb/238U年龄加权平均值为334.1Ma±2.4Ma的辉长闪长岩,暗示江绍断裂带在早古生代的构造活动可能引发了断裂带沿线及其北侧偏远处的岩浆活动,在晚古生代仍有较强的构造表现。由此可见,浙赣皖相邻区的加里东构造事件远比以往所认识的更强烈。这组年龄数据对重新认识浙赣皖相邻区和江绍断裂带的构造活动及其演化具有重要意义。
It is generally considered that the Early Paleozoic geology of northwest Zhejiang and even the adjacent areas of Zhejiang such as Anhui, and Jiangxi Provinces(ZWG) is characterized by a series of folds, faults and the regional unconformity between the Late Paleozoic as well as the underlying Presinian epimetamorphic rocks and the lower part of the Early Paleozoic strata. These features resulted from the long-distance effect of the Caledonian tectonic event that occurred in South China. In contrast, Paleozoic magmatic activities in ZWG are generally to have been poorly developed. The authors obtained LA-ICP-MS zircon U-Pb weighted average ages of 445Ma ±19Ma, 452.1Ma±2.7Ma, and 334.1Ma ±2.4Ma for the magmatic rocks from the border area of Zhejiang and Anhui Provinces and the northern side of the Jiangshan-Shaoxing fault zone respectively, implying that only an intense tectonic activity once occurred in ZWG region during the Early Paleozoic, and there also existed a tectonomagmatic event a-long the fault zone during the Late Paleozoic. These data are valuable for the better understanding of tectonic evolution of Jiangshan-Shaoxing fault.
It is generally considered that the Early Paleozoic geology of northwest Zhejiang and even the adjacent areas of Zhejiang such as Anhui, and Jiangxi Provinces(ZWG) is characterized by a series of folds, faults and the regional unconformity between the Late Paleozoic as well as the underlying Presinian epimetamorphic rocks and the lower part of the Early Paleozoic strata. These features resulted from the long-distance effect of the Caledonian tectonic event that occurred in South China. In contrast, Paleozoic magmatic activities in ZWG are generally to have been poorly developed. The authors obtained LA-ICP-MS zircon U-Pb weighted average ages of 445Ma ±19Ma, 452.1Ma±2.7Ma, and 334.1Ma ±2.4Ma for the magmatic rocks from the border area of Zhejiang and Anhui Provinces and the northern side of the Jiangshan-Shaoxing fault zone respectively, implying that only an intense tectonic activity once occurred in ZWG region during the Early Paleozoic, and there also existed a tectonomagmatic event a-long the fault zone during the Late Paleozoic. These data are valuable for the better understanding of tectonic evolution of Jiangshan-Shaoxing fault.
引文
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[20]戴圣潜,周存亭,储东如,等.下扬子东南缘北段加里东期构造形迹新资料[J].地质通报,2006,25(6):670-672.
[21]王孔忠,颜铁增,袁强.扬子东南缘北段加里东期的褶皱特征——来自不整合关系的证据[J].地质通报,2006,25(6):673-675.
[22]孙涛.新编华南花岗岩分布图及其说明[J].地质通报,2006,25(3):331-335.
[23]周新民,陈培荣,徐夕生,等.南岭地区晚中生代花岗岩成因与岩石圈动力学演化[M].北京:科学出版社,2007:5-246.
[24]朱云鹤,周新民.江绍断裂带中闪长岩类的糜棱岩化作用[J].火山地质与矿产,1994,15(1):23-34.
[25]侯可军,李延河,田有荣.LA-MC-ICP-MS锆石微区原位U-Pb定年技术[J].矿床地质,2009,28(4):481-492.
[26]水涛,徐步台,梁如华,等.绍兴―江山古陆对接带[J].科学通报,1986,(6):444-448.
[27]水涛.中国东南大陆基底构造格局[J].中国科学(D辑),1987,(1):414-422.
[28]舒良树,于津海,贾东,等.华南东段早古生代造山带研究[J].地质通报,2008,27(10):1581-1593.
[29]刘运黎,周小进,廖宗庭,等.华南加里东期相关地块及其汇聚过程探讨[J].石油实验地质,2009,31(1):19-26.
[30]周名魁,王汝植,李志明,等.中国南方奥陶—志留纪岩相古地理与成矿作用[J].北京:地质出版社,1993:1-111.
[31]任纪舜,陈廷愚,牛宝贵,等.中国东部及邻区大陆岩石圈的构造演化与成矿[M].北京:科学出版社,1990:1-218.
[32]戎嘉余,詹仁斌,许红根,等.华夏古陆于奥陶—志留纪之交的扩展证据和机制探索[M].中国科学(D辑),2010,40(1):1-17.
[33]于津海,刘潜,胡修棉,等.华南晚古生代岩浆活动的新发现:岛弧还是陆内造山?[J].科学通报,2012,57(31):2964-2971.
[2]邓家瑞,张志平.赣杭构造带区域大地构造背景的探讨[J].铀矿地质,1999,15(2):71-76.
[3]舒良树,周新民.中国东南部晚中生代构造格架[J].地质论评,2002,48(3):249-260.
[4]竺国强,张福祥,杨树锋,等.江山-绍兴碰撞带构造演化与变形特征[J].浙江大学学报,1997,31(6):743-752.
[5]Li X H,Li W X,Li Z X,et al.Amalgamation between the Yangtze and Cathaysia Blocks in South China:Constraints from SHRIMP UPb zircon ages,geochemistry and Nd-Hf isotopes of the Shuangxiwu volcanic rocks[J].Precambrian Research,2009,174:117-128.
[6]Wang X L,Zhou J C,Griffin W L,et al.Detrital zircon geochronology of Precambrian basement sequences in the Jiangnan orogen:Dating the assembly of the Yangtze and Cathaysia Blocks[J].Precambrian Research,2007,159:117-131.
[7]Wang X L,Zhao G C,Zhou J C,et al.Geochronology and Hf isotopes of zircon from volcanic rocks of the Shuangqiaoshan Group,South China:Implications for the Neoproterozoic tectonic evolution of the eastern Jiangnan orogen[J].Gondwana Research,2008,14:355-367.
[8]Wang X L,Shu L S,Xing G F,et al.Post-orogenic extension in the eastern part of the Jiangnan orogen:Evidence from ca.800~760Ma volcanic rocks[J].Precambrian Research,2012,(222/223):404-423.
[9]王丽娟,于津海,O’Reilly S Y,等.华夏南部可能存在Grenville期造山作用:来自基底变质岩中锆石U-Pb定年及Lu-Hf同位素信息[J].科学通报,2008,53(14):1680-1692.
[10]Li X H,Li Z X,Ge W C,et al.Neoproterozoic granitoids in south China:crustal melting above a mantle plume at ca.825Ma?[J].Precambrian Research,2003,122:45-83.
[11]Li X H,Li W X,Li Z X,et al.850~790Ma bimodal volcanic and intrusive rocks in northern Zhejiang,South China:A major episode of continental rift magmatism during the breakup of Rodinia[J].Lithos,2008,102:341-357.
[12]吴荣新,郑永飞,吴元保.皖南新元古代井潭组火山岩锆石U-Pb定年和同位素地球化学研究[J].高校地质学报,2007,13(2):282-296.
[13]高林志,杨明桂,丁孝忠,等.华南双桥山群和河上镇群凝灰岩中的锆石SHRIMP U-Pb年龄——对江南新元古代造山带演化的制约[J].地质通报,2008,27(10):1744-1751.
[14]Zheng Y F,Wu R X,Wu Y B,et al.Rift melting of juvenile arcderived crust:geochemical evidence from Neoproterozoic volcanic and granitic rocks in the Jiangnan Orogen,South China[J].Precambrian Research,2008,163:351-383.
[15]卢成忠,杨树锋,顾明光,等.浙江次坞地区晋宁晚期双峰式岩浆杂岩带的地球化学特征:Rodiula超大陆裂解的岩石学记录[J].岩石学报,2009,25(1):67-76.
[16]杨树锋,顾明光,卢成忠.浙江章村地区中元古代岛弧火山岩的地球化学及构造意义[J].吉林大学学报(地球科学版),2009,39(4):679-698.
[17]薛怀民,马芳,宋永勤,等.江南造山带东段新元古代花岗岩组合的年代学和地球化学:对扬子与华夏地块拼合时间与过程的约束[J].岩石学报,2010,26(11):3215-3244.
[18]王孝磊,舒徐洁,邢光福,等.浙江诸暨地区石角-璜山侵入岩LA-ICP-MS锆石U-Pb年龄——对超镁铁质球状岩成因的启示[J].地质通报,2012,31(1):75-81.
[19]余心起,张达,汪隆武,等.浙皖赣相邻区加里东期构造变形特征[J].地质通报,2006,25(6):676-684.
[20]戴圣潜,周存亭,储东如,等.下扬子东南缘北段加里东期构造形迹新资料[J].地质通报,2006,25(6):670-672.
[21]王孔忠,颜铁增,袁强.扬子东南缘北段加里东期的褶皱特征——来自不整合关系的证据[J].地质通报,2006,25(6):673-675.
[22]孙涛.新编华南花岗岩分布图及其说明[J].地质通报,2006,25(3):331-335.
[23]周新民,陈培荣,徐夕生,等.南岭地区晚中生代花岗岩成因与岩石圈动力学演化[M].北京:科学出版社,2007:5-246.
[24]朱云鹤,周新民.江绍断裂带中闪长岩类的糜棱岩化作用[J].火山地质与矿产,1994,15(1):23-34.
[25]侯可军,李延河,田有荣.LA-MC-ICP-MS锆石微区原位U-Pb定年技术[J].矿床地质,2009,28(4):481-492.
[26]水涛,徐步台,梁如华,等.绍兴―江山古陆对接带[J].科学通报,1986,(6):444-448.
[27]水涛.中国东南大陆基底构造格局[J].中国科学(D辑),1987,(1):414-422.
[28]舒良树,于津海,贾东,等.华南东段早古生代造山带研究[J].地质通报,2008,27(10):1581-1593.
[29]刘运黎,周小进,廖宗庭,等.华南加里东期相关地块及其汇聚过程探讨[J].石油实验地质,2009,31(1):19-26.
[30]周名魁,王汝植,李志明,等.中国南方奥陶—志留纪岩相古地理与成矿作用[J].北京:地质出版社,1993:1-111.
[31]任纪舜,陈廷愚,牛宝贵,等.中国东部及邻区大陆岩石圈的构造演化与成矿[M].北京:科学出版社,1990:1-218.
[32]戎嘉余,詹仁斌,许红根,等.华夏古陆于奥陶—志留纪之交的扩展证据和机制探索[M].中国科学(D辑),2010,40(1):1-17.
[33]于津海,刘潜,胡修棉,等.华南晚古生代岩浆活动的新发现:岛弧还是陆内造山?[J].科学通报,2012,57(31):2964-2971.