Tectonic, magmatic and thermal evolution of the SE China margin during breakup
Intervenant : Michael Nirrengarten
Post Doctorant, Laboratoire Géoscience et Environnement, Université de Cergy Pontoise
Recent high-quality seismic acquisitions on rifted margins around the world highlight the variability of the architecture of Continent-Ocean Transitions (COT). Drilling control, to determine the basement nature and timing of deformation are essential to constrain tectono-magmatic evolution of rifting and breakup. With the recent deep-sea drillings (IODP 349-367 & 368), high-resolution seismic images, thermal maturity data and modelling, the SE China is an ideal natural laboratory to unravel breakup processes.
Our investigations of the COT architecture highlight the major lithospheric thinning, which triggered melt production and impregnation within continental crust. With gravity modelling we determine the location of the continent ocean boundary. However, our observations suggest that the initial oceanic crust accretion is not yet localized and asymmetric before the onset of a mid-oceanic ridge.
The second aspect of this study is to compare the tectono-magmatic model with thermal maturity data in order to answer specific questions: 1) Can we record and characterize the thermal imprint of breakup in COT? 2) What is the variation in paleo heat flow in the COT for each drilled site 3) What is the pre-, syn- and post-rift thermal evolution of COT?
This study shows the interplay between extensional faulting and magmatism during breakup and assess the influence of magmatism on the thermal maturity and thermal evolution.