CAJ | 학술논문

羌塘盆地是我国陆域大型中生代海相沉积盆地,富含烃源岩,但结构构造非常复杂。结合野外观测及相关资料对地震反射剖面进行地质构造详细解释,良好地揭示了羌塘盆地结构和深部构造。羌塘盆地逆冲推覆构造延伸存在显著差别,北羌塘凹陷多格错仁逆冲推覆构造、阿木错逆冲推覆构造与南羌塘凹陷肖茶卡-双湖逆冲推覆构造、多玛-其香错逆冲推覆构造仅发育于盆地表层0~3km 深度范围,北羌塘凹陷龙尾错逆冲推覆构造、羌中隆起北缘逆冲推覆构造、南羌塘凹陷赛布错-扎加藏布逆冲推覆构造、拉萨地块北缘色林错逆冲推覆构造系统自地表向深部延伸深度超过6 km,羌塘盆地深部还发育中生界底部逆冲系和基底逆冲系,伴有不同规模的褶皱构造。逆冲推覆构造形成活动时代包括晚白垩世、古近纪早期和古近纪晚期,晚白垩世与古近纪早期逆冲推覆构造运动导致构造隆升的裂变径迹年龄分别为87±5~75±4 Ma、64±5~46±4 Ma。经过多期逆冲推覆构造改造和褶皱变形,羌塘盆地中生界海相沉积地层与烃源岩显著增厚,为新生代晚期二次生烃及油气成藏提供了非常有利的地质构造条件；北羌塘凹陷发育万安湖向斜、半岛湖背斜、东湖向斜、阿木错向斜,南羌塘凹陷发育宁日圈闭、鲁雄错背斜、诺尔玛错圈闭、协德圈闭、崩则错圈闭,羌中隆起下伏侏罗系和三叠系烃源岩,色林错下白垩统下伏古近纪湖相沉积,这些构造部位都是油气勘探的重要靶区。
강당분지시아국륙역대형중생대해상침적분지,부함경원암,단결구구조비상복잡。결합야외관측급상관자료대지진반사부면진행지질구조상세해석,량호지게시료강당분지결구화심부구조。강당분지역충추복구조연신존재현저차별,북강당요함다격착인역충추복구조、아목착역충추복구조여남강당요함초다잡-쌍호역충추복구조、다마-기향착역충추복구조부발육우분지표층0~3km 심도범위,북강당요함룡미착역충추복구조、강중륭기북연역충추복구조、남강당요함새포착-찰가장포역충추복구조、랍살지괴북연색림착역충추복구조계통자지표향심부연신심도초과6 km,강당분지심부환발육중생계저부역충계화기저역충계,반유불동규모적습추구조。역충추복구조형성활동시대포괄만백성세、고근기조기화고근기만기,만백성세여고근기조기역충추복구조운동도치구조륭승적렬변경적년령분별위87±5~75±4 Ma、64±5~46±4 Ma。경과다기역충추복구조개조화습추변형,강당분지중생계해상침적지층여경원암현저증후,위신생대만기이차생경급유기성장제공료비상유리적지질구조조건；북강당요함발육만안호향사、반도호배사、동호향사、아목착향사,남강당요함발육저일권폐、로웅착배사、낙이마착권폐、협덕권폐、붕칙착권폐,강중륭기하복주라계화삼첩계경원암,색림착하백성통하복고근기호상침적,저사구조부위도시유기감탐적중요파구。
Qiangtang basin is a large marine basin formed in the Triassic and Jurossic Periods with abundant hydrocarbon source rocks and very complicated structures.Seismic reflection together with field geological mapping reveal well deep structures of the Qiangtang Basin in northern Tibetan Plateau.The Duoge Coren Thrust (DCT)and Armu Co Thrust (ACT)in the Northern Qiangtang Depression and the Xiaochaka-Shuanghu Thrust (XST)and Doma-Qixiang Co Thrust (DQT)in the Southern Qiangtang Depression mainly formed in upper Qiangtang Basin with depth less than 3km.The Longwei Co Thrust (LCT)and Northern Central Thrust (NCT)in the northern Qiangtang,Saibu Co-Zajia Zangbu Thrust (SZT)in the southern Qiangtang,and Northern Silin Co Thrust (NST)in the northern Lhasa Block formed in upper crust with depth larger than 6km.And the Northern Bottom Thrust (NBT),Southern Bottom Thrust (SBT)and Basement Thrust (BMT)formed below Triassic marine deposits of the Qiangtang Basin. Anticlines and synclines of different sizes formed widely along major thrust faults.Most thrust systems in Qiangtang Basin formed in Late Cretaceous,Paleocene-Early Eocene and Late Eocene-Oligocene.Fission track dating of apatites further indicate that uplift caused by regional thrust occurred in 87 5~75 4Ma、64 ±5~46±4Ma,respectively,during Late Cretaceous and Early Paleogene.Regional thrust and folding in Late Cretaceous-Early Tertiary leads to evident thickening of the Triassic and Jurassic marine strata and hydrocarbon source rocks,which provides favorite geological setting for hydrocarbon generation and oil-gas accumulation after intensive thrust stopped in Late Oligocene-Early Miocene.The Wananhu syncline, Baodaohu anticline,Donghu syncline and Armu Co syncline in the Northern Qiangtang Depression, together with the Ningri trap,Luxiongco anticline,the Norma trap,Xiede trap and Bengze Co trap as well as Triassic-Jurassic marine source rocks beneath thrust sheets of the Paleozoic basement rocks in Central Qiangtang Uplift and Paleocene-Oligocene lacustrine deposits beneath frontier thrust fault of the NST,are all important targets for oil-gas exploration in the Qiangtang Basin and its adjacent areas.