Probing crustal thickness evolution and geodynamic processes in the past from magma records: An integrated approach
2017; Geological Society of America; Linguagem: Inglês
10.1130/2017.2526(01)
ISSN2331-219X
AutoresJérôme Ganne, Wouter P. Schellart, Gideon Rosenbaum, Xiaojun Feng, Vincent De Andrade,
Tópico(s)High-pressure geophysics and materials
ResumoA new and simple integrated approach is proposed for qualitatively unravelling the crustal thickness of fossil magmatic systems based on the chemical and thermal records in amphibole-bearing magmatic rocks. Statistical analyses applied to a large multidimensional amphibole database show that Ti-rich and Si-poor magmatic amphiboles, which formed at high-temperature (T) conditions (>950 °C), were dominantly developed in basaltic to basaltic-andesitic (SiO2-poor, i.e., 40 km) Jurassic to Cretaceous accretionary belt along the circum-Pacific orogenic belts that bounded the Panthalassa Ocean. The destruction of this thick belt started at ca. 125 Ma and was initially recorded by the thinnest magmatic systems hosting amphibole-bearing magma. Thinning of the circum-Pacific orogenic belts became widespread in the northern regions of western America and in the western Pacific after ca. 75 Ma, possibly in response to oceanic plate segmentation, which triggered slab rollback and overriding plate extension.
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