Geochronology and geochemistry of late Paleozoic volcanic rocks from eastern Inner Mongolia, NE China: Implications for igneous petrogenesis, tectonic setting, and geodynamic evolution of the south-eastern Central Asian Orogenic Belt
Geochronology and geochemistry of late Paleozoic volcanic rocks from eastern Inner Mongolia, NE China: Implications for igneous petrogenesis, tectonic setting, and geodynamic evolution of the south-eastern Central Asian Orogenic Belt
复制标题
内蒙古东部晚古生代火山岩年代学和地球化学：对中亚造山带东南部火成岩、构造环境和地球动力学演化的启示
DOI：
10.1016/j.lithos.2020.105480
复制
发表时间：
2020-06
期刊：
影响因子：
3.5
通讯作者：
Ming-Qian Wang
中科院分区：
文献类型：
--
作者：
Peng-Rui Cai;Tao Wang;Zong-Qi Wang;Long-Ming Li;Jian-Liang Jia;Ming-Qian Wang
本文报道了内蒙古科尔沁右翼前旗大石寨地区大石寨组火山岩的新岩石学、地球化学、单键铅锆石年代学和Hf同位素结果。火山岩由镁铁质到长英质的块状岩石组成，包括玄武岩、流纹岩、玄武岩安山岩、安山岩、英安岩和流纹质凝灰岩。英安岩和流纹岩凝灰岩的激光消融-电感耦合等离子体质谱(LA-ICP-MS)206Pb/238U锆石年龄分别为332 Ma±11 Ma和300 Ma±11 Ma，表明长英质火山作用发生的时间为早石炭世至晚石炭世。镁铁质火山岩样品富含大离子亲石元素(LILE)和轻稀土元素(LREE；La/Nb=1.58-4.84)，亏损高场强元素(HFSe；Th/Yb比值和Lt；2.2)和重稀土元素[HREE；(Tb/Yb)N1.27-1.91]。根据这些微量元素特征，我们认为镁铁质火山岩代表了来自俯冲变质和熔体亏损的地幔楔体的分馏的高程度部分熔体。长英质火山岩产生富LILE和LREE的成分以及弧形的HFSE和HREE贫化特征。从流纹岩凝灰岩和英安岩样品中回收的岩浆锆石的εHf(T)值为正(+1.2 1~+14.85)，两阶段Hf模式年龄分别为1 2 36 Ma和3 91 Ma，表明弧状长英质火山作用来自于大石寨组下较老的年轻下地壳或与其相互作用。因此，大石寨地区的镁铁质-长英质火山岩可能形成于大陆边缘的石炭纪岩浆弧中。根据大石寨地区石炭-二叠纪火山岩的同位素和地球化学特征，初步将内蒙古中部和东部划分为三个带：(1)北带，形成于岩浆活动大陆边缘；(2)中带，形成于大陆边缘的岩浆弧；(3)南带，形成于大洋岛弧。大石寨组的年龄和地球化学特征表明，早石炭世至早二叠世期间，大石寨组向北活动俯冲，表明早二叠世后古亚洲洋关闭。
Here we report new petrography, geochemistry, Usingle bondPb zircon geochronology, and Hf isotope results for volcanic rocks of the Dashizhai Formation in the Dashizhai area, Keerqin Right Wing Front Banner, Inner Mongolia. The volcanic rocks have mafic to felsic bulk-rock compositions and include basalt, rhyolite, basaltic andesite, andesite, dacite, and rhyolitic tuff. Two dacite and rhyolitic tuff samples yield laser ablation–inductively coupled plasma–mass spectrometry (LA–ICP–MS)206Pb/238U zircon ages of 332 ± 1 Ma and 300 ± 1 Ma, respectively, suggesting that the timing of felsic volcanism ranged from the early to late Carboniferous. Mafic volcanic rock samples are enriched in large-ion lithophile elements (LILE) and light rare earth elements (LREE; La/Nb = 1.58–4.84), and are depleted in high-field-strength elements (HFSE; Th/Yb ratios <2.2) and heavy rare earth elements [HREE; (Tb/Yb)Nratios 1.27–1.91]. Based on these trace element characteristics, we propose that the mafic volcanic rocks represent fractionated, high-degree partial melts that were sourced from the subduction-modified and melt-depleted mantle wedge. The felsic volcanic rocks yield LILE- and LREE-rich compositions and arc-like HFSE- and HREE-poor signatures. Magmatic zircons recovered from the dated rhyolitic tuff and dacite samples yield positive εHf(t) values (+1.21 to +14.85) and two-stage Hf model ages of 1236 and 391 Ma, suggesting that arc-like felsic volcanism was sourced from, and/or interacted with, the older juvenile lower-crust underlying the Dashizhai Formation. Therefore, the mafic to felsic volcanic rocks from the Dashizhai area likely formed in a Carboniferous magmatic arc at a continental margin. Based on the isotopic and geochemical signatures of the Carboniferous–Permian volcanic rocks in the Dashizhai area, we preliminarily divide central and eastern Inner Mongolia into three zones: (i) North Zone, which formed at the magmatically active continental margin; (ii) Middle Zone, which formed in a magmatic arc peripheral to the continental marginal; and (iii) South Zone, which formed in an oceanic island arc. The age and geochemical signature of the Dashizhai Formation points to active, northward subduction during the early Carboniferous to the early Permian and suggests that the Paleo-Asian Ocean closed after the early Permian.
登录
查看更多内容
中亚造山带西部：增生造山作用和大陆生长的窗口
影响因子：
6.1
作者：
Wenjiao Xiao;M. Santosh
通讯作者：
M. Santosh
影响因子：
--
作者：
Cui Qing-qing
通讯作者：
Cui Qing-qing
影响因子：
1.5
作者：
Fu-Yuan Wu;Jin-Hui Yang;C. Lo;S. Wilde;Dejun Sun;B. Jahn
通讯作者：
Fu-Yuan Wu;Jin-Hui Yang;C. Lo;S. Wilde;Dejun Sun;B. Jahn
影响因子：
4.9
作者：
A. Naidu;T. C. Mowatt
通讯作者：
A. Naidu;T. C. Mowatt
DOI：
10.1144/sp318.1
发表时间：
2009-01-01
期刊：
EARTH ACCRETIONARY SYSTEMS IN SPACE AND TIME
影响因子：
--
作者：
Cawood, Peter A.;Kroener, Alfred;Windley, Brian F.
通讯作者：
Windley, Brian F.