A Mantle Plume Origin for the Scandinavian Dyke Complex: A “Piercing Point” for 615 Ma Plate Reconstruction of Baltica?
A Mantle Plume Origin for the Scandinavian Dyke Complex: A “Piercing Point” for 615 Ma Plate Reconstruction of Baltica?
复制标题
斯堪的纳维亚岩脉复合体的地幔柱起源：波罗的海板块 615 Ma 重建的“穿透点”？
DOI：
10.1029/2018gc007941
复制
发表时间：
2019
期刊：
影响因子：
3.7
通讯作者：
T. Torsvik
中科院分区：
文献类型：
--
作者：
C. Tegner;T. Andersen;H. J. Kjøll;E. Brown;G. Hagen;F. Corfu;S. Planke;T. Torsvik
与大陆解体有关的大型火成岩省(LIP)的起源和超过3.2亿年(前盘古大陆)的大陆重建都是有争议的研究问题。在这里，我们研究了一个615-590 Ma的辉绿岩岩墙杂岩的岩石学，它侵入了波罗的海富含岩浆的裂谷盆地，现在暴露在斯堪的纳维亚加里多尼德山脉中。这些岩墙是中央伊帕图斯岩浆省(CIMP)的一部分，CIMP是在加里东威尔逊旋回开始时侵位在波罗的海和劳伦西亚的嘴唇。>；1000公里长的岩墙杂岩从南到北表现出从富玄武岩成分到亏损玄武岩成分的横向分带。常量元素和微量元素的地球化学模拟表明，这些成分最好的解释是在环境地幔上方75-250℃的热地幔熔融。尽管微量元素模型的解决方案不是唯一的，但最好的解释是熔融具有丰富和亏损橄榄岩岩性的横向分带地幔热柱，类似于今天的冰岛和北大西洋火成岩省。CIMP的起源似乎涉及到几个地幔热柱。如果裂谷和裂解岩浆作用与地核边界大的低剪切波速度省(LLSVP)边缘的羽流产生区重合，这是最好的解释。如果像最近的地球动力学模型所说的那样，LLSVP在时间上是准静止的，那么CIMP就为重建6.15亿年前波罗的海和劳伦蒂亚的古地理提供了指南，现在LLSVP位于太平洋之下。我们的结果为使用唇部作为钢板重建的穿刺点提供了刺激。
The origin of Large Igneous Provinces (LIPs) associated with continental breakup and the reconstruction of continents older than ca. 320 million years (pre‐Pangea) are contentious research problems. Here we study the petrology of a 615–590 Ma dolerite dyke complex that intruded rift basins of the magma‐rich margin of Baltica and now is exposed in the Scandinavian Caledonides. These dykes are part of the Central Iapetus Magmatic Province (CIMP), a LIP emplaced in Baltica and Laurentia during opening of the Caledonian Wilson Cycle. The >1,000‐km‐long dyke complex displays lateral geochemical zonation from enriched to depleted basaltic compositions from south to north. Geochemical modelling of major and trace elements shows these compositions are best explained by melting hot mantle 75–250 °C above ambient mantle. Although the trace element modelling solutions are nonunique, the best explanation involves melting a laterally zoned mantle plume with enriched and depleted peridotite lithologies, similar to present‐day Iceland and to the North Atlantic Igneous Province. The origin of CIMP appears to have involved several mantle plumes. This is best explained if rifting and breakup magmatism coincided with plume generation zones at the margins of a Large Low Shear‐wave Velocity Province (LLSVP) at the core mantle boundary. If the LLSVPs are quasi‐stationary back in time as suggested in recent geodynamic models, the CIMP provides a guide for reconstructing the paleogeography of Baltica and Laurentia 615 million years ago to the LLSVP now positioned under the Pacific Ocean. Our results provide a stimulus for using LIPs as piercing points for plate reconstructions.