Geochemical evidence for a lithospheric source for magmas from Acoculco Caldera, eastern Mexican volcanic belt.
Verma, Surendra P (2001) Geochemical evidence for a lithospheric source for magmas from Acoculco Caldera, eastern Mexican volcanic belt. International Geology Review. 43; 1, Pages 31-51. 2001.
| Authors | Verma, Surendra P |
|---|---|
| Year | 2001 |
| Title | Geochemical evidence for a lithospheric source for magmas from Acoculco Caldera, eastern Mexican volcanic belt. |
| Source | International Geology Review. 43; 1, Pages 31-51. 2001. |
| Publisher | Winston & Son. Silver Spring, MD, United States. 2001. |
| Document type | Serial |
| ISSN | 0020-6814 |
| GeoRef | 2002-078037 |
| Keywords | Acoculco-Caldera; alkaline-earth-metals; andesites-; basalts-; calderas-; Deep-Sea-Drilling-Project; DSDP-Site-487; DSDP-Site-488; eastern-Mexican-volcanic-belt; geochemistry-; igneous-rocks; IPOD-; isotope-ratios; isotopes-; Leg-66; lithosphere-; magmas-; major-elements; mantle-; metals-; Mexican-volcanic-belt; Mexico-; mid-ocean-ridge-basalts; Nd-144-Nd-143; neodymium-; P-T-conditions; partial-melting; petrography-; phase-equilibria; provenance-; Puebla-Mexico; rare-earths; rhyolites-; sampling-; Sr-87-Sr-86; stable-isotopes; strontium-; trace-elements; upper-mantle; volcanic-features; volcanic-rocks |
Abstract
This study reports new geochemical and Sr-Nd-Pb radiogenic isotope data on eight samples of hy-normative Quaternary basaltic-to-rhyolitic volcanic rocks from Acoculco caldera, located in the state of Puebla, Mexico, at the eastern part of the Mexican Volcanic Belt MVB. The isotopic ratios of basaltic rocks are as follows: super 87 Sr/ super 86 Sr approximately 0.70383, super 143 Nd/ super 144 Nd approximately 0.51283, super 206 Pb/ super 204 Pb approximately 18.78, super 207 Pb/ super 204 Pb approximately 15.60, and super 208 Pb/ super 204 Pb approximately 38.49. These isotopic ratios are somewhat similar to the rift-related basic rocks from Los Humeros caldera, eastern MVB, as well as from the Sierra de Chichinautzin monogenetic field along the volcanic front of the central MVB. For comparison, all samples from basalt to rhyolite in the Acoculco area show the following ranges: super 87 Sr/ super 86 Sr 0.703824-0.706413, super 143 Nd/ super 144 Nd 0.512685-0.512837, super 206 Pb/ super 204 Pb 18.778-18.810, super 207 Pb/ super 204 Pb 15.599-15.628, and super 208 Pb/ super 204 Pb 38.487-38.608. The basaltic rocks from the Acoculco caldera do not show the characteristic negative Nb anomaly with respect to Ba and Ce, as is typical of such magmas in volcanic arcs. Available geochemical and isotopic evidence does not support the generation of these basic magmas by direct slab melting or indirect fluid transport to the mantle participation of the subducted Cocos plate. They could be generated in the upper mantle from a lithospheric source, similar to that proposed recently for the nearby Los Humeros caldera. The evolved basaltic trachyandesitic, basaltic andesitic, and rhyolitic magmas could have originated from such basaltic magmas through assimilation coupled with fractional crystallization. All available geological, geochemical, and geophysical evidence also supports the recently proposed tectonic-petrogenetic model for the origin of magmas in the MVB.