摘要
锆石U Pb定年结果显示:东天山大南湖头苏泉岛弧带中酸性侵入岩形成时代为古生代,处于465~265 Ma,可划分为4个期次。分别为:中奥陶世—晚志留世465~413 Ma、中—晚泥盆世391~377 Ma、石炭纪327~308 Ma,以及早—中二叠世284~269 Ma。锆石Hf同位素分析显示,锆石εHf(t)值为6.81~15.73,Hf同位素二阶段模式年龄为839~355 Ma,主要集中在598~429 Ma;465~413 Ma的侵入岩分布在卡拉塔格和大南湖,其εHf(t)值为11.34~15.20,相应的Hf同位素二阶段模式年龄为633~467 Ma;391~377 Ma的侵入岩分布于卡拉塔格,其εHf(t)值为6.81~13.32,相应的Hf同位素二阶段模式年龄为839~497 Ma;327~308 Ma的侵入岩分布在黄山西以及沁城南,其εHf(t)值为11.36~15.73,相应的Hf同位素二阶段模式年龄为575~429 Ma;284~269 Ma的侵入岩分布在土屋西和推克曼塔什,其εHf(t)值为8.94~14.51,相应的Hf同位素二阶段模式年龄是671~355 Ma。再结合前人的研究成果揭示,在大南湖头苏泉岛弧带底部可能存在老的地壳基底,并对这些岩浆活动有所贡献;该区古生代期间存在大约465 Ma早奥陶世以及330 Ma左右中石炭世2期地壳增生事件,并存在晚奥陶世—晚志留世、中—晚泥盆世和早—中二叠世三期地壳再造事件。
Zircon U-Pb dating results show that the emplacement ages of intermediate-acid intrusive rocks in the Dananhu-Tousuquan island arc of the eastern Tianshan Mountains is between 465—265 Ma in the Paleozoic era.It can be divided into 4 periods:Middle Ordovician to Late Silurian(465—413 Ma),Middle Devonian(391—377 Ma),Carboniferous(327—308 Ma),and Early-Middle Permian(284—269 Ma).Zircon Hf isotope analysis shows thatεHf(t)values range from 6.81 to 15.73 with the two-stage Hf model ages 839 Ma—355 Ma,mainly at 598 Ma—429 Ma.The intrusive rocks aged 465—413 Ma are distributed in Kalatage and Dananhu,with theεHf(t)values ranging from 11.34 to 15.20,and the two-stage Hf model ages ranging from 633 Ma to 467 Ma.The 391—377 Ma intrusive rocks occurred in the Karatag,with theεHf(t)value ranging from 6.81 to 13.32,and two-stage Hf model ages ranging from 839 Ma to 497 Ma.The intrusive rocks dated 327—308 Ma are exposed in the west of Huangshan and south of Qincheng,with theεHf(t)value ranging from 11.36 to 15.73,and the two-stage Hf model ages ranging from 575 Ma to 429 Ma.The intrusive rocks with ages of 284—269 Ma are distributed in the west of Tuwu and Tuikemantashi,with theεHf(t)value ranging from 8.94 to 14.51,and the two-stage Hf model ages ranging from 671 Ma to 355 Ma.Combined with previous studies,this paper guesses that the old crustal basements beneath the Dananhu-Tou Suquan island arc contribute a lot to the paleozoic magmatic activities.In Palaeozoic era there were significant crustal accretion events near the Early Ordovician 465 Ma and the Middle Carboniferous 330 Ma in the arc,whereas in Late Ordovician-Late Silurian,Middle-Late Devonian and Early-Middle Permian crustal-reworking events occurred.
作者
庞博宸
李秋根
陈隽璐
刘树文
王宗起
陈衍景
肖兵
PANG Bochen;LI Qiugen;CHEN Junlu;LIU Shuwen;WANG Zongqi;CHEN Yanjing;XIAO Bing(Key Laboratory of Orogenic Belts and Crustal Evolution(MOE),School of Earth and Space Sciences,Peking University,Beijing 100871,China;Xi'an Center of China Geological Survey,Xi'an 710054,Shaanxi,China;Institute of Mineral Resources,Chinese Academy of Geological Sciences,Beijing 100037,China;Guangzhou Institute of Geochemistry,Chinese Academy of Sciences,Guangzhou 510640,Guangdong,China)
出处
《西北地质》
CAS
CSCD
北大核心
2020年第2期1-26,共26页
Northwestern Geology
基金
国家重点基础研究发展计划(“九七三”计划)“新疆北部古弧盆体系成矿机理”项目(2014CB440801)
中国地质调查局“准噶尔古生代增生造山的岩浆作用与成矿”项目(12120113041000)
中国地质调查局“塔里木前寒武纪铁块成因类型及层控规律研究”项目(1212011140056)。
关键词
地壳演化
锆石U
Pb定年
锆石HF同位素
大南湖头苏泉岛弧带
东天山
crustal evolution
zircon U-Pb dating
zircon Hf isotopes
Dananhu-Tousuquan island arc
eastern Tianshan Mountains
