Geochemical probing of continental lithosphere through time in transported terranes

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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? To build on previous research, I will investigate the coupling/decoupling of the SCLM and crust primarily during the Paleozoic evolution of peri-Gondwanan terranes. These transported terranes originated along the margin of Gondwana (precursor supercontinent) in the Neoproterozoic, rifted from that margin in the Early Paleozoic and were transferred across an ocean to collide with Laurentia or Baltica (precursor continents) before the end of the Paleozoic.