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Intra‐arc opening and closure of a marginal sea: The case of the Guerrero Terrane (SW Mexico)
Author(s) -
Monod Olivier,
Faure Michel,
Salinas JuanCarlos
Publication year - 1994
Publication title -
island arc
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.554
H-Index - 58
eISSN - 1440-1738
pISSN - 1038-4871
DOI - 10.1111/j.1440-1738.1994.tb00002.x
Subject(s) - geology , flysch , cretaceous , paleontology , terrane , volcanic arc , basement , cenomanian , island arc , continental margin , volcanic rock , volcano , back arc basin , subduction , tectonics , civil engineering , engineering
The pre‐Oligocene structure of southwest Mexico, south of the trans‐Mexico volcanic axis, is investigated from Taxco (Guerrero state, abbreviation: Gro) to the Pacific coast. Three volcano‐sedimentary units are recognized; from east to west the calc‐alkaline Teloloapan, tholeiitic Arcelia and calc‐alkaline Zihuatanejo suites. Structural and stratigraphic data show that the Teloloapan volcanic arc, active during ?Late Jurassic and early Cretaceous, was built upon continental basement. The Teloloapan lavas are overlain by the Albian–Cenomanian Morelos platform carbonates and followed by the Upper Cretaceous Mexcala flysch. In contrast, the Arcelia pillow lavas are associated with sandstones and cherts of Albian‐?Cenomanian age. The Zihuatanejo arc was also installed upon continental basement and its magmatic activity was in part coeval with Arcelia magmatism. Unlike the almost undeformed Zihuatanejo volcanic rocks, all the other volcanic units are involved in east‐vergent thrusting and recumbent folding associated with ductile tectonics, as well as the Late Cretaceous Mexcala flysch overlying the Morelos platform carbonates. Contrasting with previous views, the present results do not support a major mid‐Cretaceous thrusting event in the study area. The new geodynamic interpretation proposed here considers that the Arcelia rocks were formed in a marginal basin situated east of the Zihuatanejo arc. Closure of this basin in Paleocene times is responsible for the east vergent thrust tectonics in SW Mexico.