Tectono-magmatic evolution of Late Jurassic to Early Cretaceous granitoids in the west central Lhasa subterrane, Tibet
Tectono-magmatic evolution of Late Jurassic to Early Cretaceous granitoids in the west central Lhasa subterrane, Tibet
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西藏拉萨地块中西部晚侏罗世至早白垩世花岗岩的构造岩浆演化
DOI：
10.1016/j.gr.2016.01.006
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发表时间：
2016-11
影响因子：
6.1
通讯作者：
Pete Hollings
中科院分区：
文献类型：
--
作者：
MingJian Cao;KeZhang Qin;GuangMing Li;JinXiang Li;JunXing Zhao;Noreen J. Evans;Pete Hollings
关于班公-怒江洋中生代俯冲方向（向北、向南或双向俯冲）一直存在争议。与弧相关的中英质侵入岩可以标志俯冲带的位置，更重要的是阐明主导的地球动力学过程。本文报道了拉萨中西部E80°~ E86°地下花岗岩类的全岩地球化学和锆石U-Pb、Hf同位素数据。所有岩石均表现出金属-过铝质、钙碱性特征，Nb、Ta、Ti富集，Cs、Rb、K等大离子亲石元素富集，sio2与P2O5呈负相关，Rb与Th呈正相关。这些特征均为i型弧岩浆活动的标志。新的锆石U-Pb结果和文献资料表明，晚侏罗世至早白垩世（160 ~ 130 Ma）存在持续的岩浆活动。拉萨地下中西部北部（E80°~ E82°30′）锆石U-Pb年龄为165 ~ 150 Ma，南部锆石U-Pb年龄为142 ~ 130 Ma。这表明班公-怒江洋发生了平缓或低角度的俯冲作用，与晚侏罗世岩石锆石εHf(t)值略有向南下降相一致。考虑到地壳缩短、离班公-怒江缝合带的距离以及典型的俯冲带熔融深度~ 100 km，拉萨中部地区晚侏罗世岩浆活动的俯冲角度小于14°，符合平或低角度俯冲。早白垩世岩石（145 ~ 130 Ma）的εHf(t)值明显高于晚侏罗世岩石（主要εHf(t)值为- 16 ~ - 7），主要εHf(t)值为- 8 ~ 0，可能是由于板块沉降或断裂引起的板块回滚。结合前人关于拉萨中部和羌塘南部地下西部弧岩浆活动的研究成果，我们的研究结果支持班公-怒江洋沿班公-怒江缝合带的双向俯冲，表明班公-怒江洋沿班公-怒江缝合带呈平缓或低角度向南俯冲（165 ~ 145 Ma），然后是板块回滚（145 ~ 130 Ma）。
There is ongoing debate as to the subduction direction of the Bangong–Nujiang Ocean during the Mesozoic (northward, southward or bidirectional subduction). Arc-related intermediate to felsic intrusions could mark the location of the subduction zone and, more importantly, elucidate the dominant geodynamic processes. We report whole rock geochemical and zircon U–Pb and Hf isotopic data for granitoids from the west central Lhasa subterrane (E80° to E86°). All rocks show metaluminous to peraluminous, calc-alkaline signatures, with strong depletion of Nb, Ta and Ti, enrichment of large ion lithophile elements (e.g., Cs, Rb, K), a negative correlation between SiO2and P2O5, and a positive correlation between Rb and Th. All these features are indicative of I-type arc magmatism. New zircon U–Pb results, together with data from the literature, indicate continuous magmatism from the Late Jurassic to the Early Cretaceous (160 to 130 Ma). Zircon U–Pb ages for samples from the northern part of the west central Lhasa subterrane (E80° to E82°30′) yielded formation ages of 165 to 150 Ma, whereas ages of 142 to 130 Ma were obtained on samples from the south. This suggests flat or low-angle subduction of the Bangong–Nujiang Ocean, consistent with a slight southward decrease in zircon εHf(t) values for Late Jurassic rocks. Considering the crustal shortening, the distance from the Bangong–Nujiang suture zone, and a typical subduction zone melting depth of ~ 100 km, the subduction angle was less than 14° for Late Jurassic magmatism in the central Lhasa interior, consistent with flat or low-angle subduction. Compared with Late Jurassic rocks (main εHf(t) values of − 16 to − 7), Early Cretaceous rocks (145 to 130 Ma) show markedly higher εHf(t) values (mainly − 8 to 0), possibly indicating slab roll-back, likely caused by slab foundering or break-off. Combined with previously published works on arc magmatism in the central Lhasa and west part of the southern Qiangtang subterranes, our results support the bidirectional subduction of the Bangong–Nujiang Ocean along the Bangong–Nujiang Suture Zone, and indicates flat or low-angle southward subduction (165 to 145 Ma) followed by slab roll-back (145 to 130 Ma).
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影响因子：
3.5
作者：
Jinxiang Li;K. Qin;Guangming Li;J. Richards;Junxing Zhao;Mingjian Cao
通讯作者：
Jinxiang Li;K. Qin;Guangming Li;J. Richards;Junxing Zhao;Mingjian Cao
影响因子：
5.3
作者：
G. Rosenbaum;D. Giles;M. Saxon;P. Betts;R. Weinberg;C. Duboz
通讯作者：
G. Rosenbaum;D. Giles;M. Saxon;P. Betts;R. Weinberg;C. Duboz
影响因子：
1.8
作者：
V. Ramos;E. Cristallini;D. Pérez
通讯作者：
V. Ramos;E. Cristallini;D. Pérez
影响因子：
4.9
作者：
A. Pullen;P. Kapp;G. Gehrels;L. Ding;Qinghai Zhang
通讯作者：
A. Pullen;P. Kapp;G. Gehrels;L. Ding;Qinghai Zhang
DOI：
10.1111/1755-6724.12439
发表时间：
2015-04
期刊：
Acta Geologica Sinica ‐ English Edition
影响因子：
--
作者：
Yin Zhengxin;Yuan Yajuan;Lü Baofeng;Cai Zhourong;Zheng Hao;Huang Qiang-tai;X. Bin;Zhong Yun
通讯作者：
Yin Zhengxin;Yuan Yajuan;Lü Baofeng;Cai Zhourong;Zheng Hao;Huang Qiang-tai;X. Bin;Zhong Yun