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Mesozoic‐Cenozoic Regional Stress Field Evolution in Svalbard
Tectonics ( IF 3.3 ) Pub Date : 2020-04-17 , DOI: 10.1029/2018tc005461
Harmon Maher 1 , Kim Senger 2 , Alvar Braathen 2, 3 , Mark Joseph Mulrooney 3 , Aleksandra Smyrak‐Sikora 2, 4 , Per Terje Osmundsen 5 , Kei Ogata 6, 7
Affiliation  

Cooling fracture orientations in diabase sills associated with the Cretaceous High Arctic Large Igneous Province and syn‐sedimentary Triassic faults help constrain a model for Svalbard's (NE Barents Shelf) Mesozoic stress field evolution. Fracture data from Edgeøya and adjacent islands in SE Svalbard, from S Spitsbergen, and from literature were used to model preferred orientations and temporal relationships. Orthogonal, roughly E‐W and N‐S, joints and veins in sills from SE Svalbard are interpreted as cooling fractures influenced by the ambient stress field. Aligned preferred orientations within the Triassic host strata are associated with a regional Cretaceous jointing episode driven by sill emplacement and/or erosional unloading. The regional maximum horizontal stress (likely σ1) is inferred to have been parallel to a dominant ≈E‐W set. Spitsbergen's more complex joint patterns are associated with proximity to the Cenozoic West Spitsbergen Fold‐and‐Thrust Belt, but ≈E‐W and ≈N‐S orientations occur and are typically the earlier set. Syn‐sedimentary, ≈NW‐SE striking, Triassic normal faults in SE Svalbard aligned with the maximum horizontal stress indicate a Triassic to Cretaceous counterclockwise stress field shift, with additional counterclockwise shifting during Cenozoic dextral transpression between Svalbard and Greenland. Localized joint preferred orientations consistent with both decoupled and coupled transpression occur. Changes in the regional maximum horizontal stress and deformation regime may reflect timing of which plate margin was crucial in influencing Svalbard's plate interior stress field, starting with Triassic Uralian activity to the E, then Cretaceous Amerasian Basin development to the NW, culminating with Cenozoic dextral transpression and transtension to the SW.

中文翻译:

斯瓦尔巴特群岛中,新生代区域应力场演化

与白垩纪高北极大火成岩省和同沉积的三叠纪断层有关的辉绿岩基岩的冷却裂缝取向有助于约束斯瓦尔巴德(NE Barents Shelf)中生代应力场演化模型。来自东南部斯瓦尔巴群岛的Edgeøya和邻近岛屿,S斯匹次卑尔根岛以及文献的断裂数据被用来模拟优选的方位和时间关系。SE斯瓦尔巴群岛的窗台中的正交(大致为E-W和N-S),关节和静脉被解释为受环境应力场影响的冷却裂缝。在三叠纪主层内对齐的首选方位与由基岩位置和/或侵蚀性卸载驱动的区域白垩纪节理事件有关。推断区域最大水平应力(可能为σ1)与主导≈E-W集平行。斯匹次卑尔根更复杂的节理模式与新生代西斯匹次卑尔根褶皱冲断带的接近程度有关,但是≈E和≈NS方向发生并且通常是较早的方向。同沉积,≈NW-SE走向,东南部斯瓦尔巴群岛的三叠纪正断层与最大水平应力对齐,表明三叠纪至白垩纪逆时针方向的应力场发生了位移,在斯瓦尔巴德群岛和格陵兰之间新生代右旋逆转过程中还发生了逆时针方向的额外位移。发生与去耦和耦合压抑相一致的局部关节优选取向。区域最大水平应力和变形机制的变化可能反映出板块边缘对斯瓦尔巴德板块内部应力场的影响至关重要的时机,从三叠纪乌拉尔活动到E,
更新日期:2020-04-17
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