Geochemical probing of continental lithosphere through time in transported terranes

地球化学研究表明，与裂谷有关的玄武岩通常继承了其地幔来源的同位素特征。大多数研究集中于在很短的时间间隔内侵位的火山岩或深成岩套，然后将这些岩石与邻近地体中的同时代岩套进行比较。我的方法是研究特定地体中与裂谷有关的火成岩套在长时间范围内的地球化学/同位素特征。这种方法使我能够在不同的构造环境下评价地壳和下伏的次大陆岩石圈地幔(SCLM，刚性岩石圈板块的下部)之间的长期关系，并确定在裂谷、漂移和吸积等重大构造事件期间，地壳和SCLM是否耦合。在这些事件中，地壳和南海地壳之间的潜在耦合/去耦合对于识别和理解全球尺度的构造和岩浆作用至关重要。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)地体在横渡大洋时是否保留其SCLM？(Ii)碰撞造山作用后是否发生了SCLm交代？(3)超级大陆之下的超级烟柱是否取代了小岛屿环流？以及(Iv)地壳和南海地壳之间的耦合是持久的和普遍的，还是随着时间的推移而变化的，如果是这样的话，什么时候和为什么？

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?