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塘古兹巴斯坳陷中生代地层缺失严重,中生代以来的构造发育、隆升过程,是该区构造-沉积演化的难点。裂变径迹低温热年代学技术是近年来用于沉积盆地热史研究的新技术,在地质热事件定年、地质体热演化历史、构造区隆升与剥蚀等方面应用十分广泛,在确定隆升过程及热历史上有其独到的优越性。本文通过塘参1井钻井岩心样品的裂变径迹实验和热演化史模拟,结合地层发育情况,揭示了塘古兹巴斯坳陷中-新生代存在5个冷却抬升-增温沉降旋回,即248~240Ma(早-中三叠世)、199~120Ma(三叠纪末-早白垩世)、72~55Ma(晚白垩世-古新世)、24~15Ma(晚渐新世-早中新世)和7.4~2.2Ma(中新世晚期-上新世)等5个抬升冷却期,期间为沉降沉积期。此5个冷却阶段的平均冷却速率的变化具有先增后降的过程,从三叠纪至中新世期,平均冷却速率逐渐增大;在早中新世达到最大为4.22℃/Myr;晚中新世至今,平均冷却速率逐渐减小。反映了中-新生代以来隆升最快的时期为喜马拉雅中期(24~15Ma)。持续最长时间的抬升表现在侏罗纪-早白垩世中期,塘古兹巴斯坳陷处于前缘隆起,未接受沉积,并使中上三叠统沉积地层遭受剥蚀。且塘古兹巴斯坳陷中古生代及晚古生代早期沉积地层,在早-中三叠世前经历了较高的古地温,致使磷灰石样品发生完全退火,锆石样品部分退火,不同于相邻的巴楚地区。塘古兹巴斯坳陷热演化过程中冷却(抬升)及增温(沉降)事件的发生时期,与古特提斯、新特提斯闭合及印度-亚洲碰撞的关键时刻相吻合,可作为青藏高原多阶段构造运动的响应。
The serious lack of Mesozoic strata in Tangutzizabad depression and the tectonic uplift and uplift process since the Mesozoic are the cruxes of structural-sedimentary evolution in this area. Fission track low temperature thermochronology is a new technique used in thermal history research of sedimentary basins in recent years. It is widely used in geothermal thermal event dating, history of thermal evolution of geological body, uplift and erosion of tectonic area, Process and thermal history has its own unique advantages. Based on the fission track experiment and thermal history simulation of the core sample of well Tanshen 1 and the development of the stratum, it is revealed that there are 5 cooling-warming-depositional cycles in the Mesozoic-Cenozoic in the Tangut Zaizidian depression, ie, 248 ~ 240 Ma (Early-Middle Triassic), 199 ~ 120 Ma (Late Triassic-Early Cretaceous), 72 ~ 55 Ma (Late Cretaceous- Paleocene), 24 ~ 15 Ma (Late Oligocene- Pliocene) and 7.4 ~ 2.2Ma (Late Pliocene-Pliocene). During the period of sedimentation, the sedimentation period was 5. The average cooling rate in the five cooling stages changed first and then decreased. From the Triassic to the mid-Miocene, the average cooling rate gradually increased, reaching a maximum of 4.22 ° C / Myr in the Early Miocene and late Since the Miocene, the average cooling rate has gradually decreased. It reflects the mid-Himalayan medium term (24 ~ 15Ma) with the fastest rise since the Meso-Cenozoic. The longest sustained uplift occurred during the Middle Jurassic-Early Cretaceous period, with the Tangguz-baz depression uplifted in the frontal margin and unaccounted for sedimentation, leaving the middle and upper Triassic sedimentary formations eroded. In addition, the Paleozoic and Early Paleozoic sedimentary formations in the Tangut Zuzipud depression experienced higher Paleogene temperatures before the Early Middle Triassic, resulting in complete annealing of the apatite samples and partial annealing of the zircon samples. Neighboring Bachu area. The occurrence of cooling (uplifting) and warming (sedimentation) events during the thermal evolution of the Tangutzizasi depression, coinciding with the key points of the closure of the Gt Tethys, the Neo-Tethyan closure and the India-Asia collision, Responses of Multistage Tectonic Movement on the Tibetan Plateau.