The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are ...The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are well-developed Paleozoic-Cenozoic strata in this basin,and these provide a crucial window to a greater understanding of the amalgamation process and source-to-sink relationships between the Alxa Block and surrounding tectonic units.However,due to intensive post-depositional modification,and lack of subsurface data,several fundamental issues-including the distribution and evolution of the depositional systems,provenance supplies and source-to-sink relationships during the Carboniferous-Permian remain unclear and thus hinder hydrocarbon exploration and limit the geological understanding of this basin.Employing integrated outcrop surveys,new drilling data,and detrital zircon dating,this study examines the paleogeographic distribution and evolution,and provenance characteristics of the Carboniferous-Permian strata in the Bayanhot Basin.Our results show that the Bayanhot Basin experienced a long-term depositional evolution process from transgression to retrogression during the Carboniferous-late Permian.The transgression extent could reach the central basin in the early Carboniferous.The maximum regional transgression occurred in the early Permian and might connect the Qilian and North China seas with each other.Subsequently,a gradual regression followed until the end of the Permian.The northwestern NCC appeared as a paleo-uplift area and served as a sediments provenance area for the Alxa Block at that time.The NCC,Bayanwula Mountain,and NQOB jointly served as major provenances during the Carboniferous-Permian.There was no ocean separation,nor was there an orogenic belt between the Alxa Block and the NCC that provided sediments for both sides during the Carboniferous-Permian.The accretion of the Alxa and North China blocks should have been completed before the Carboniferous period.展开更多
基金supported by National Key R&D Program Project of China(Grant No.2017YFC0603106)the Opening Foundation of State Key Laboratory of Continental Dynamics,Northwest University,China(Grant No.201210140)。
文摘The Bayanhot Basin is a superimposed basin that experienced multiple-staged tectonic movements;it is in the eastern Alxa Block,adjacent to the North China Craton(NCC)and the North Qilian Orogenic Belt(NQOB).There are well-developed Paleozoic-Cenozoic strata in this basin,and these provide a crucial window to a greater understanding of the amalgamation process and source-to-sink relationships between the Alxa Block and surrounding tectonic units.However,due to intensive post-depositional modification,and lack of subsurface data,several fundamental issues-including the distribution and evolution of the depositional systems,provenance supplies and source-to-sink relationships during the Carboniferous-Permian remain unclear and thus hinder hydrocarbon exploration and limit the geological understanding of this basin.Employing integrated outcrop surveys,new drilling data,and detrital zircon dating,this study examines the paleogeographic distribution and evolution,and provenance characteristics of the Carboniferous-Permian strata in the Bayanhot Basin.Our results show that the Bayanhot Basin experienced a long-term depositional evolution process from transgression to retrogression during the Carboniferous-late Permian.The transgression extent could reach the central basin in the early Carboniferous.The maximum regional transgression occurred in the early Permian and might connect the Qilian and North China seas with each other.Subsequently,a gradual regression followed until the end of the Permian.The northwestern NCC appeared as a paleo-uplift area and served as a sediments provenance area for the Alxa Block at that time.The NCC,Bayanwula Mountain,and NQOB jointly served as major provenances during the Carboniferous-Permian.There was no ocean separation,nor was there an orogenic belt between the Alxa Block and the NCC that provided sediments for both sides during the Carboniferous-Permian.The accretion of the Alxa and North China blocks should have been completed before the Carboniferous period.
文摘臭氧(O_(3))作为地球大气中重要的微量成分,平均含量10~100 ppb,平流层集中了大部分O_(3),而对流层O_(3)含量仅占总量的10%左右。平流层O_(3)可降低太阳紫外线进入地球,保护人类及动植物。近地面污染物浓度及其扩散、反应、沉降等过程在很大程度上依赖于上层混合及垂直边界层的物理状况,如夜间残留层的O_(3)在次日可以被下沉运动带到地面,从而使地面的O_(3)浓度升高,甚至影响近地面的光化学污染进程。因此,利用差分吸收O_(3)激光雷达对阿拉善盟巴彦浩特环保局新楼站点附近O_(3)时空分布特征进行连续观测,研究了阿拉善盟巴彦浩特地区O_(3)日变化时空分布特征,分析了本地生成和区域传输两种类型的O_(3)污染来源。结果显示:巴彦浩特大气O_(3)监测时段日变化时空分布特征显著,一般在午后呈现典型的单峰特征;在O_(3)本地生成过程中,近地面O_(3)主要呈现高浓度,同时高度增大O_(3)浓度逐渐减小,高值O_(3)主要集中在1 km以下,1.5~2 km O_(3)浓度变化趋势平缓,并结合气象场分析了山谷风环流特征对O_(3)浓度的影响。
