Why is Svalbard an island? Evidence for two‐stage uplift, magmatic underplating, and mantle thermal anomalies
Why is Svalbard an island? Evidence for two‐stage uplift, magmatic underplating, and mantle thermal anomalies
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DOI：
10.1002/tect.20039
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发表时间：
2013-06
期刊：
影响因子：
4.2
通讯作者：
N. Dörr;P. Clift;F. Lisker;C. Spiegel
中科院分区：
文献类型：
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作者：
N. Dörr;P. Clift;F. Lisker;C. Spiegel
斯瓦尔巴特群岛是东北大西洋巴伦支大陆架的一个异常的陆上部分。在这项研究中，我们进行了基于盆地结构，水深和热年代学的一维和二维沉降分析，以量化和确定新生代期间影响斯瓦尔巴特群岛的隆升阶段。斯瓦尔巴群岛经历了两个阶段的隆升，从>36到~10 Ma，并从~10 Ma开始，在时间上与格陵兰岛，斯堪的纳维亚半岛和巴伦支大陆架确定的隆升阶段相似。斯瓦尔巴特群岛中央第三纪盆地大部分地区的总隆起超过1.5公里，西斯匹次卑尔根褶皱带（WSFB）的部分地区超过2.5公里。>36 ~~10 Ma的地壳运动占垂直运动的绝大部分，且与年轻阶段一样，向东幅度减小。岩石圈的抗弯刚度估计较低（Te <5 km），因此36 Ma后WSFB的侵蚀对隆升的贡献很小，其永久性和与同步的Yermak高原的接近有利于与区域岩浆底侵作用的联系。沿西转换板块边缘沿着的地幔柱动力支撑和挠曲卸载对垂直运动的影响可以排除。自~10 Ma以来的重新隆升，产生现代地形可能与斯瓦尔巴特群岛下地幔岩石圈的热侵蚀有关。我们认为，大部分的表面隆起的一个可能的原因是向北传播的Duppovich海岭建立连续的海底扩张通过弗拉姆海峡后~10马。
Svalbard is an anomalous, subaerial part of the Barents Shelf, Northeast Atlantic Ocean. In this study, we performed both, one‐ and two‐dimensional subsidence analyses based on basin structure, water depth, and thermochronology, to quantify and date the phases of uplift affecting Svalbard during the Cenozoic. Svalbard has experienced two phases of uplift, from >36 to ~10 Ma, and since ~10 Ma, similar in timing to uplift phases identified in Greenland, Scandinavia, and the Barents Shelf. Total uplift across much of the Central Tertiary Basin of Svalbard is >1.5 km and exceeds 2.5 km in parts of the West Spitsbergen Foldbelt (WSFB). Uplift from >36 to ~10 Ma accounts for the greatest part of the vertical motion and like the younger phase reduces in magnitude towards the east. Flexural rigidity of the lithosphere is estimated to be low (Te ≈ 5 km), so that post‐36 Ma erosion of the WSFB contributes little to the uplift, whose permanent nature and proximity to the synchronous Yermak Plateau favors a link to regional magmatic underplating. Plume dynamic support and flexural unloading along the western transform plate margin can be ruled out as influences on vertical motions. Since ~10 Ma renewed uplift, generating the modern topography may be linked to thermal erosion of the mantle lithosphere under Svalbard. We suggest that a likely cause of much of the surface uplift is the northward propagation of the Knipovich Ridge to establish continuous seafloor spreading through the Fram Strait after ~10 Ma.