Geochemical probing of continental lithosphere through time in transported terranes

地球化学研究表明，与裂谷相关的玄武岩通常继承了其地幔来源的同位素特征。大多数研究都集中在很短的时间间隔内形成的火山岩或深成岩组，然后将这些岩石与相邻地体中的同时代岩组进行比较。我的方法是长期研究特定地体中与裂谷相关的火成岩套的地球化学/同位素特征。这种方法使我能够评估各种构造背景下地壳和底层次大陆岩石圈地幔（SCLM，刚性岩石圈板块的下部）之间的长期关系，并确定地壳和 SCLM 在裂谷、漂移和增生等主要构造事件期间是否耦合。这些事件期间地壳和 SCLM 之间潜在的耦合/解耦对于识别和理解全球尺度的构造和岩浆过程至关重要。 SCLM变化的证据（或缺乏证据）将回答重要的地球动力学问题，例如（i）地体在跨越海洋转移时是否保留其SCLM？ (ii) SCLM 是否在碰撞造山作用后被取代？ (iii) 超级地幔柱是否会取代超大陆下方的 SCLM？ (iv) 地壳与 SCLM 之间的耦合是否持久且普遍，或者是否随时间变化？如果是，何时以及为何变化？

Geochemical studies show that rift-related basaltic rocks typically inherit the isotopic signature of their mantle sources. Most studies focus on suites of volcanic or plutonic rocks that were emplaced within a narrow time interval and then compare these rocks with coeval suites in adjacent terranes. My approach is to investigate the geochemical/ isotopic characteristics of rift-related igneous suites in specific terranes over a long range of time. This approach enables me to evaluate the long-term relationship between the crust and the underlying sub-continental lithospheric mantle (SCLM, the lower part of the rigid lithospheric plate) in a variety of tectonic settings, and to determine whether or not the crust and SCLM were coupled during the major tectonic events such as rifting, drifting and accretion. The potential coupling/decoupling between the crust and the SCLM during these events is critical to the identification and understanding of the global-scale tectonic and magmatic processes. Evidence (or a lack thereof) for changes in the SCLM will answer important geodynamic questions such as (i) do terranes retain their SCLM when transferred across an ocean? (ii) is the SCLM replaced following collisional orogenesis? (iii) do superplumes replace the SCLM beneath supercontinents? and (iv) is coupling between the crust and SCLM enduring and common or does it change with time, and if so, when and why?