当前位置: X-MOL 学术Precambrian. Res. › 论文详情
Our official English website, www.x-mol.net, welcomes your feedback! (Note: you will need to create a separate account there.)
Tectonic evolution of the Alxa Block and its affinity: Evidence from the U-Pb geochronology and Lu-Hf isotopes of detrital zircons from the Longshoushan Belt
Precambrian Research ( IF 3.8 ) Pub Date : 2020-07-01 , DOI: 10.1016/j.precamres.2020.105733
Jingna Liu , Changqing Yin , Jian Zhang , Jiahui Qian , Shun Li , Kaiyuan Xu , Shangjing Wu , Yanfei Xia

Abstract The NW-SE trending Longshoushan Belt is a significant transitional belt between the Alxa and Qilian blocks. Its basement rocks were predominated by greenschist- to amphibolite-facies metamorphosed volcanic-sedimentary rocks, which were named the Longshoushan Complex and sporadically exposed in the middle and eastern Longshoushan Belt. The U-Pb ages of detrital zircons from the middle Longshoushan are scattered in the period of 3006–1981 Ma, predominated by Paleoproterozoic (>95%) with a single peak of 2.0 Ga. These zircons have the 176Hf/177Hf ratios of 0.281150–0.281687, corresponding to hafnium model ages (TDMC) of 3.04–2.15 Ga. These age features are in accordance with those of the Alxa Block and the western North China Craton. In contrast, the protoliths of the eastern Longshoushan reveal a wide age range from 3389 Ma to 529 Ma, which can be apparently divided into four age populations of 2.5 Ga, 1.6 Ga, 1.0 Ga and 0.8 Ga. This is consistent with recent reported age data of the Hexi Corridor, indicating that the eastern Longshoushan is not a part of the Longshoushan Complex, but has affinity with the Hexi Corridor. The cumulative probability curves of measured crystallization ages and depositional ages of detrital zircons imply that the middle Longshoushan could be deposited in a convergent basin (e.g., back-arc basin) in the Paleoproterozoic, but the eastern Longshoushan was typical of tectonic setting of a collisional basin (e.g., a foreland basin) in the Cambrian. The closure of the North Qilian Ocean formed the North Qilian Orogen between the Central Qilian and Alxa blocks, resulting to a foreland basin in the Hexi Corridor (i.e., eastern Longshoushan).

中文翻译:

阿拉善地块的构造演化及其亲和力:来自龙首山带碎屑锆石U-Pb年代学和Lu-Hf同位素的证据

摘要 NW-SE向龙首山带是阿拉善地块与祁连地块之间的重要过渡带。其基岩以绿片岩-角闪岩相变质火山-沉积岩为主,命名为龙首山杂岩体,零星出露于龙首山带中东部。龙首山中段碎屑锆石U-Pb年龄分散在3006-1981 Ma期间,以古元古代为主(>95%),单峰为2.0 Ga。这些锆石的176Hf/177Hf比值为0.2810-176Hf。 0.281687,对应于3.04-2.15 Ga的铪模型年龄(TDMC)。这些年龄特征与阿拉善地块和华北克拉通西部的年龄特征一致。相比之下,龙首山东部的原岩年龄范围很广,从 3389 Ma 到 529 Ma,明显可分为2.5 Ga、1.6 Ga、1.0 Ga和0.8 Ga 4个年龄群体。这与近期报道的河西走廊年龄数据一致,说明龙首山东部不是龙首山杂岩体的一部分,而是与河西走廊有缘。碎屑锆石实测结晶年龄和沉积年龄累积概率曲线表明,龙首山中部可能沉积于古元古代的辐合盆地(如弧后盆地),而龙首山东部则为典型的碰撞构造环境。寒武纪盆地(例如前陆盆地)。北祁连洋的闭合在中祁连地块与阿拉善地块之间形成北祁连造山带,形成河西走廊前陆盆地(即龙首山东部)。
更新日期:2020-07-01
down
wechat
bug