大地构造与成矿学
大地構造與成礦學
대지구조여성광학
Geotectonica et Metallogenia
2015年
5期
780-794
,共15页
刘绍军%高庚%朱德丰%吴根耀%王金奎%张革%孙效东%刘赫%李春柏%李强
劉紹軍%高庚%硃德豐%吳根耀%王金奎%張革%孫效東%劉赫%李春柏%李彊
류소군%고경%주덕봉%오근요%왕금규%장혁%손효동%류혁%리춘백%리강
北东向伸展断裂%北东东-近东西向剪切变换断裂%近南北向剪切断裂%盆地演化%早白垩世%南贝尔凹陷%塔木察格盆地
北東嚮伸展斷裂%北東東-近東西嚮剪切變換斷裂%近南北嚮剪切斷裂%盆地縯化%早白堊世%南貝爾凹陷%塔木察格盆地
북동향신전단렬%북동동-근동서향전절변환단렬%근남북향전절단렬%분지연화%조백성세%남패이요함%탑목찰격분지
NE-orientated extensional fault%NEE-/near WE-striking transit fracture%near NS-striking shear fracture%basin evolution%Early Cretaceous%the South Buir Sag%the Tamtsag Basin
塔木察格盆地南贝尔凹陷早白垩世的断裂发育可分为早、晚两期。早期(铜钵庙组?南屯组沉积期)为北东向同生断层的伸展(或张扭)活动，可细分为4幕，分别发生在铜钵庙组、南一段下部、南一段上部和南二段沉积期。因北东东?近东西向断裂的左行剪切变换，其南、北两侧发育的北东向盆地有不同的特征，北为2个相背而倾的箕状断陷，南为2个相向而倾的箕状断陷。晚期为近南北向断裂的右行剪切，分2幕：第 I 幕发生在大磨拐组沉积的早?中期，除新生断裂外还有南二段沉积期形成的张扭性断裂的继承性活动；第 II 幕发生在大磨拐河组沉积晚期?伊敏组沉积早期。早期的北东向断裂晚期再度活动并遭受了不同程度的改造。基于上述认识分两阶段重塑了南贝尔凹陷早白垩世的演化，并与塔南凹陷进行了对比，发现东部次凹的构造活动性大于西部次凹，即：后者以北东向断裂为主而前者以近南北向断裂为主，北东东?近东西向断裂在东部次凹发育更好，南屯组沉积期末的隆起造成东部剥蚀的地层厚度更大。
塔木察格盆地南貝爾凹陷早白堊世的斷裂髮育可分為早、晚兩期。早期(銅缽廟組?南屯組沉積期)為北東嚮同生斷層的伸展(或張扭)活動，可細分為4幕，分彆髮生在銅缽廟組、南一段下部、南一段上部和南二段沉積期。因北東東?近東西嚮斷裂的左行剪切變換，其南、北兩側髮育的北東嚮盆地有不同的特徵，北為2箇相揹而傾的箕狀斷陷，南為2箇相嚮而傾的箕狀斷陷。晚期為近南北嚮斷裂的右行剪切，分2幕：第 I 幕髮生在大磨枴組沉積的早?中期，除新生斷裂外還有南二段沉積期形成的張扭性斷裂的繼承性活動；第 II 幕髮生在大磨枴河組沉積晚期?伊敏組沉積早期。早期的北東嚮斷裂晚期再度活動併遭受瞭不同程度的改造。基于上述認識分兩階段重塑瞭南貝爾凹陷早白堊世的縯化，併與塔南凹陷進行瞭對比，髮現東部次凹的構造活動性大于西部次凹，即：後者以北東嚮斷裂為主而前者以近南北嚮斷裂為主，北東東?近東西嚮斷裂在東部次凹髮育更好，南屯組沉積期末的隆起造成東部剝蝕的地層厚度更大。
탑목찰격분지남패이요함조백성세적단렬발육가분위조、만량기。조기(동발묘조?남둔조침적기)위북동향동생단층적신전(혹장뉴)활동，가세분위4막，분별발생재동발묘조、남일단하부、남일단상부화남이단침적기。인북동동?근동서향단렬적좌행전절변환，기남、북량측발육적북동향분지유불동적특정，북위2개상배이경적기상단함，남위2개상향이경적기상단함。만기위근남북향단렬적우행전절，분2막：제 I 막발생재대마괴조침적적조?중기，제신생단렬외환유남이단침적기형성적장뉴성단렬적계승성활동；제 II 막발생재대마괴하조침적만기?이민조침적조기。조기적북동향단렬만기재도활동병조수료불동정도적개조。기우상술인식분량계단중소료남패이요함조백성세적연화，병여탑남요함진행료대비，발현동부차요적구조활동성대우서부차요，즉：후자이북동향단렬위주이전자이근남북향단렬위주，북동동?근동서향단렬재동부차요발육경호，남둔조침적기말적륭기조성동부박식적지층후도경대。
The fractural development of the South Buir Sag of the Tamtsag Basin during the Early Cretaceous could be divided into two phases. The fractural activities in the early phase, namely, the depositional period of the Tongbomiao-Nantun Formations, are characterized by the NE-orientated synsedimentary extensional (or transtensile) faulting. It could be further divided into four episodes, occurring in the depositional periods of the Tongbomiao Formation, the lower part of No.1 Member of the Nantun Formation, the upper part of No.1 Member of the Nantun Formation, and the No.2 Member of the Nantun Formation, respectively. Owing to the sinistral shearing transit of the NEE-/near WE-striking fractures, the NE-orientated basins at either side of the transit belt have varied features. To the north of the transit belt, there developed two normal faults dipped back-to-back. Moreover, each fault controlled a half-graben developing on its upper plate, and the two half-grabens are separated by the Sudert Fault-Rise. To the south of it there occurred two normal faults dipped face-to-face, and two half-grabens on the hanging walls were joined each other on their southern terminals. The fractural mobilization in the late phase displayed a dextral shearing of the near NS-striking fractures, and two shear episodes could be distinguished. The first episode took place in the early-middle stage of the depositional period of the Damoguaihe Formation, during which some neogenic shear faults created, and in addition, the transtensile faults formed in the No.2 Member of the Nantun Formation rejuvenated. The second episode occurred in the latest depositional period of the Damoguaihe Formation and the earliest sedimentary stage of the Yimin Formation. The early phase NE-orientated faults remobilized in the late phase and reformed in varying degrees. Corresponding to the two-phase fractural activities, the two-phase basin evolution is reconstructed, and compared with that of the Tanan Sag to the south. A peculiarity for the South Buir Sag is that the East Sub-sag has stronger tectonic mobility than the West Sub-sag. The NE-orientated faults are relatively well preserved in the West Sub-sag, while in the East Sub-sag the structural framework is composed of the nearly NS-striking fractures as well as the NEE-/near WE-striking fractures. Furthermore, subsequent to the deposition of the Nantun Formation, the basin closed and the regional uplift, moreover, the eroded stratigraphic thickness in the East Sub-sag is much larger than that of the West Sub-sag.
