The Yubei-Tangbei area in the southern Tarim Basin is one of the best-preserved Early Paleozoic northeast-southwest trending fold-and-thrust belts within this basin.This area is crucial for the exploration of primary ...The Yubei-Tangbei area in the southern Tarim Basin is one of the best-preserved Early Paleozoic northeast-southwest trending fold-and-thrust belts within this basin.This area is crucial for the exploration of primary hydrocarbon reservoirs in northwestern China.In this study,we constructed the structural geometric morphology of the Yubei-Tangbei area using geophysical logs,drilling,and recent two-and three-dimensional(2-D and 3-D)seismic data.The Early Paleozoic fault-propagation folds,the Tangnan triangle zone,fault-detachment folds,and trishear fault-propagation folds developed with the detachment of the Middle Cambrian gypsum–salt layer.According to a detailed chronostratigraphic framework,the growth strata in the Upper Ordovician–Lower Silurian layer formed by onlapping the back limb of the asymmetric fault-propagation folds,which therefore defines the timing of deformations.The changes in kink band hinges and amplitudes in the Permian–Carboniferous and Cenozoic folding strata suggest that the evolution of the fold-and-thrust belts followed a sequential evolution process rather than a simultaneous one.Above the pre-existing Precambrian basement structure,the Yubei-Tangbei fold-and-thrust belts can be divided into four tectonic evolution stages:Late Cambrian,Late Ordovician to Early Carboniferous,Carboniferous to Permian,and Cenozoic.The northwestern-verging Cherchen Fault is part of the piedmont fold-and-thrust system of the southern Tarim foreland basin.We interpreted its strata as a breakthrough trishear fault-propagation fold that developed in three phases:Mid–Late Ordovician,Silurian to Middle Devonian,and Triassic to present.These tectonic events are responses of the Altyn-Tagh and Kunlun collisional orogenic belts and the Indian-Eurasian collision.The inherited deformation and structural modification in the southern Tarim Basin may be an indicator of the growth and evolution of peripheral orogens.展开更多
Through synthetic researches of multi-index geological records of Niya section, which are of high resolution in southern margin of Tarim Basin, this paper has reconstructed the sequences of paleoclimate in this region...Through synthetic researches of multi-index geological records of Niya section, which are of high resolution in southern margin of Tarim Basin, this paper has reconstructed the sequences of paleoclimate in this region during historical times (since about 4000a B.P.). During the last 4000 years, the area has experienced alternations of relative cold-moisture and relative warm-dry periods. Three evident cold-moisture periods and three warm-dry periods are identifing. The study shows that the human activities have an intimate relation with the evolution of paleoclimate in the southern Xinjiang. Paleoclimate has played very important role in influencing human being′s agricultural activities.展开更多
This study shows that the intrusive rocks distributed in the Aoyiqieke-Tamuqi area on the southern margin of the Tarim Block are composed of gabbro, diorite, granodiorite and granite, which constitute regionally a nea...This study shows that the intrusive rocks distributed in the Aoyiqieke-Tamuqi area on the southern margin of the Tarim Block are composed of gabbro, diorite, granodiorite and granite, which constitute regionally a nearly EW-trending tectono-magmatic belt. Petrochemically the diorite, granodiorite and granite belong to the calc-alkaline, high-K series, with Na 2O/K 2O ratios varying between 0.83 and 2.63. M/F ratios in the diorite are within the range of 0.44- 0.70 and those of the granodiorite (granite) are 0.45- 0.87. Petrochemistry data show that the intrusive complexes are of the I type and their ΣREE is slightly variable, within the range of 178.31- 229.01×10 -6. The LREE/HREE ratios of the diorite and granite are 3.78- 5.13 and 6.69- 7.66, respectively. The plutons usually show moderate negative Eu anomalies with δEu values ranging from 0.53 to 0.82, showing almost no difference among different rocks. The (La/Yb) N values of diorite and granite are 12.39- 14.86 and 22.07- 26.03, respectively. The diorite and granite possess very similar REE distribution patterns, indicating that they were both derived from the same source. As for their trace element ratios, the diorite has higher Nb/Ta ratios than the granite, which are 15.73- 17.16 and 12.03- 15.01, respectively. It can be seen that the Nb/Ta ratios of the diorite are much closer to the average mantle ( 17.5). Their Zr/Hf ratios are very close to each other, within the range of 29-34. Th/Y ratios in the diorite are 0.42- 0.80 (all less than unity) while those of the granite are 1.02- 2.04. Some difference is also noticed in Ti/V between the diorite and the granite ( 52.6- 54.2 for the former and 52.6- 54.2 for the latter). As compared with ocean ridge granites, both diorite and granite are characterized by remarkable LILE enrichment, as well as by moderate negative Ba and postive Ce anomalies. The contents of Nb and Ta in the diorite and granite are equivalent to those of the ocean ridge granites, but the contents of Zr, Hf, Sm, Y, and Yb are all lower than those of the ocean ridge granites, indicating that these granites are similar to the island-arc granites of Chile. From their geochemical characteristics, it is considered that the intrusive rocks in the area studied were formed in an island-arc environment at the continental margin.展开更多
出露于新疆塔里木南缘铁克里克地区西段的都维吐卫花岗岩体,侵入赫罗斯坦岩群（Pt1 H ）黑云二长片麻岩中,与库浪那古岩群（Pt2 K ）和大同西岩体呈断层接触,东部多被博查特塔格组（Jxbc ）不整合覆盖。通过地球化学分析,显示岩体具高 S...出露于新疆塔里木南缘铁克里克地区西段的都维吐卫花岗岩体,侵入赫罗斯坦岩群（Pt1 H ）黑云二长片麻岩中,与库浪那古岩群（Pt2 K ）和大同西岩体呈断层接触,东部多被博查特塔格组（Jxbc ）不整合覆盖。通过地球化学分析,显示岩体具高 Si、高 Al、高 K,贫 Na、低 Ga、低 P、低 Ti 和贫 Mg 的特征,铝饱和指数（A/CNK）为1.38~1.43,CIPW 标准刚玉分子大于1%,属高钾钙碱性过铝质花岗岩。在稀土元素方面显示,轻稀土元素（LREE）富集、重稀土元素（HREE）亏损,轻重稀土元素分馏明显,Eu 出现中等负异常（δEu=0.59~0.82）；在微量元素方面,明显富集大离子亲石元素 Rb、Ba、Th 和 K,亏损高场强元素 Nb、Ta、Ti。岩体 LA ICP MS 锆石 U Pb 同位素定年获得年龄为（1909±47）Ma,属于古元古代花岗岩。综合分析认为该岩体是造山晚期同碰撞环境下形成的,与加厚地壳引起的地壳重熔有关,推断西昆仑造山带强烈的陆内造山活动应在古元古代已经开始了；结合赫罗斯坦岩群（Pt1 H ）中角闪斜长片麻岩中锆石年龄记录,推断2000~1800Ma塔里木陆块存在 Columbia 超大陆聚合事件。展开更多
基金This research was supported by the National Key R and D Plan of China(2017YFC0601405)the National Natural Science Foundation of China(U19B6003 and 41702110).
文摘The Yubei-Tangbei area in the southern Tarim Basin is one of the best-preserved Early Paleozoic northeast-southwest trending fold-and-thrust belts within this basin.This area is crucial for the exploration of primary hydrocarbon reservoirs in northwestern China.In this study,we constructed the structural geometric morphology of the Yubei-Tangbei area using geophysical logs,drilling,and recent two-and three-dimensional(2-D and 3-D)seismic data.The Early Paleozoic fault-propagation folds,the Tangnan triangle zone,fault-detachment folds,and trishear fault-propagation folds developed with the detachment of the Middle Cambrian gypsum–salt layer.According to a detailed chronostratigraphic framework,the growth strata in the Upper Ordovician–Lower Silurian layer formed by onlapping the back limb of the asymmetric fault-propagation folds,which therefore defines the timing of deformations.The changes in kink band hinges and amplitudes in the Permian–Carboniferous and Cenozoic folding strata suggest that the evolution of the fold-and-thrust belts followed a sequential evolution process rather than a simultaneous one.Above the pre-existing Precambrian basement structure,the Yubei-Tangbei fold-and-thrust belts can be divided into four tectonic evolution stages:Late Cambrian,Late Ordovician to Early Carboniferous,Carboniferous to Permian,and Cenozoic.The northwestern-verging Cherchen Fault is part of the piedmont fold-and-thrust system of the southern Tarim foreland basin.We interpreted its strata as a breakthrough trishear fault-propagation fold that developed in three phases:Mid–Late Ordovician,Silurian to Middle Devonian,and Triassic to present.These tectonic events are responses of the Altyn-Tagh and Kunlun collisional orogenic belts and the Indian-Eurasian collision.The inherited deformation and structural modification in the southern Tarim Basin may be an indicator of the growth and evolution of peripheral orogens.
基金Great Base Project of National Natural Science Foundation of China (No.49761007 and 49861005) International Science Research As
文摘Through synthetic researches of multi-index geological records of Niya section, which are of high resolution in southern margin of Tarim Basin, this paper has reconstructed the sequences of paleoclimate in this region during historical times (since about 4000a B.P.). During the last 4000 years, the area has experienced alternations of relative cold-moisture and relative warm-dry periods. Three evident cold-moisture periods and three warm-dry periods are identifing. The study shows that the human activities have an intimate relation with the evolution of paleoclimate in the southern Xinjiang. Paleoclimate has played very important role in influencing human being′s agricultural activities.
文摘This study shows that the intrusive rocks distributed in the Aoyiqieke-Tamuqi area on the southern margin of the Tarim Block are composed of gabbro, diorite, granodiorite and granite, which constitute regionally a nearly EW-trending tectono-magmatic belt. Petrochemically the diorite, granodiorite and granite belong to the calc-alkaline, high-K series, with Na 2O/K 2O ratios varying between 0.83 and 2.63. M/F ratios in the diorite are within the range of 0.44- 0.70 and those of the granodiorite (granite) are 0.45- 0.87. Petrochemistry data show that the intrusive complexes are of the I type and their ΣREE is slightly variable, within the range of 178.31- 229.01×10 -6. The LREE/HREE ratios of the diorite and granite are 3.78- 5.13 and 6.69- 7.66, respectively. The plutons usually show moderate negative Eu anomalies with δEu values ranging from 0.53 to 0.82, showing almost no difference among different rocks. The (La/Yb) N values of diorite and granite are 12.39- 14.86 and 22.07- 26.03, respectively. The diorite and granite possess very similar REE distribution patterns, indicating that they were both derived from the same source. As for their trace element ratios, the diorite has higher Nb/Ta ratios than the granite, which are 15.73- 17.16 and 12.03- 15.01, respectively. It can be seen that the Nb/Ta ratios of the diorite are much closer to the average mantle ( 17.5). Their Zr/Hf ratios are very close to each other, within the range of 29-34. Th/Y ratios in the diorite are 0.42- 0.80 (all less than unity) while those of the granite are 1.02- 2.04. Some difference is also noticed in Ti/V between the diorite and the granite ( 52.6- 54.2 for the former and 52.6- 54.2 for the latter). As compared with ocean ridge granites, both diorite and granite are characterized by remarkable LILE enrichment, as well as by moderate negative Ba and postive Ce anomalies. The contents of Nb and Ta in the diorite and granite are equivalent to those of the ocean ridge granites, but the contents of Zr, Hf, Sm, Y, and Yb are all lower than those of the ocean ridge granites, indicating that these granites are similar to the island-arc granites of Chile. From their geochemical characteristics, it is considered that the intrusive rocks in the area studied were formed in an island-arc environment at the continental margin.
文摘出露于新疆塔里木南缘铁克里克地区西段的都维吐卫花岗岩体,侵入赫罗斯坦岩群（Pt1 H ）黑云二长片麻岩中,与库浪那古岩群（Pt2 K ）和大同西岩体呈断层接触,东部多被博查特塔格组（Jxbc ）不整合覆盖。通过地球化学分析,显示岩体具高 Si、高 Al、高 K,贫 Na、低 Ga、低 P、低 Ti 和贫 Mg 的特征,铝饱和指数（A/CNK）为1.38~1.43,CIPW 标准刚玉分子大于1%,属高钾钙碱性过铝质花岗岩。在稀土元素方面显示,轻稀土元素（LREE）富集、重稀土元素（HREE）亏损,轻重稀土元素分馏明显,Eu 出现中等负异常（δEu=0.59~0.82）；在微量元素方面,明显富集大离子亲石元素 Rb、Ba、Th 和 K,亏损高场强元素 Nb、Ta、Ti。岩体 LA ICP MS 锆石 U Pb 同位素定年获得年龄为（1909±47）Ma,属于古元古代花岗岩。综合分析认为该岩体是造山晚期同碰撞环境下形成的,与加厚地壳引起的地壳重熔有关,推断西昆仑造山带强烈的陆内造山活动应在古元古代已经开始了；结合赫罗斯坦岩群（Pt1 H ）中角闪斜长片麻岩中锆石年龄记录,推断2000~1800Ma塔里木陆块存在 Columbia 超大陆聚合事件。
