The dynamic history of the Trans-Mexican Volcanic Belt and the Mexico subduction zone

详细信息	查看全文 | 推荐本文 |

• 作者：Luca Ferrari^a ; ^b ; ^{luca@geociencias.unam.mx} ; Teresa Orozco-Esquivel^a ; Vlad Manea^a ; Marina Manea^a
• 关键词：Trans-Mexican Volcanic Belt ; Cocos plate ; Rivera plate ; Subduction dynamics ; Arc volcanism ; Mexico crust and lithosphere
• 刊名：Tectonophysics
• 出版年：2012
• 期刊代码：82_00401951
• 类别：ear
• 出版时间：5 February, 2012
• 卷：522-523
• 期：Complete
• 页码：122-149
• 文件大小：8128 K

摘要

The Trans-Mexican Volcanic Belt (TMVB) is a 1000 km long Neogene continental arc showing a large variation in composition and volcanic style, and an intra-arc extensional tectonics. It overlies the Rivera and Cocos slabs, which display marked changes in geometry. Geophysical studies indicate that lithospheric mantle is very thin or absent beneath the forearc and arc, the fluids from the slab are released in a 40 to 100 km wide belt beneath the frontal part of the arc, and the lower crust beneath the arc is partially molten. East of 101掳W the TMVB is built on a Precambrian to Paleozoic crust with thickness of 50-55 km. West of 101掳W the TMVB is underlain by Jurassic to Cenozoic marine and continental arcs with a 35-40 km thick crust.

The evolution of the TMVB occurred in four stages: 1) from ~ 20 to 10 Ma the initial andesitic arc moved inland showing progressively drier melting and, eventually, slab melting, suggesting flattening of the subducted slab; 2) since ~ 11 Ma a pulse of mafic volcanism migrated from west to east reaching the Gulf of Mexico by 7 Ma. This mafic lavas marks the lateral propagation of a slab tear, triggered by cessation of subduction beneath Baja California; 3) thereafter, the volcanic front started moving trenchward, with a marked phase of silicic volcanism between 7.5 and 3 Ma, local emplacement of small volume intraplate-like basalts since 5 Ma, and development of extensional faulting. These features are related to slab rollback, enhancing asthenophere flux into the mantle wedge and promoting partial melting of the crust; 4) the modern arc consists of a frontal belt dominated by flux and slab melting, and a rear belt characterized by more differentiated rocks or by mafic lavas with little or no evidence of subduction fluids but higher asthenosphere fingerprint.