We found a match
Your institution may have rights to this item. Sign in to continue.
- Title
Geochemistry and Sr- Nd- Pb isotopic constraints on the petrogenesis of Cenozoic lavas from the Pali Aike and Morro Chico area (52° S), southern Patagonia, South America.
- Authors
Choo, Mi Kyung; Lee, Mi Jung; Lee, Jong Ik; Kim, Kyu Han; Park, Kye-Hun
- Abstract
Geochemical and isotopic analyses ( Sr- Nd- Pb) of late Miocene to Quaternary plateau lavas from the Pali Aike and Morro Chico areas (52° S) were undertaken to constrain the melting processes and mantle sources that contributed to magma generation and the geodynamic evolution of southernmost Patagonia, South America. The Pali Aike and Morro Chico lavas are alkaline ( Pali Aike, 45-49 wt.% Si O2; 4.3-5.9 wt.% Na2 O+ K2 O) and subalkaline ( Morro Chico, 50.5-50.8 wt.% SiO2; 4.0-4.4 wt.% Na2 O+ K2 O), relatively primitive ( Pali Aike, 9.5-13.7 wt.% Mg O; Morro Chico, 7.6-8.8 wt.% Mg O) mafic volcanic rocks that have typical intraplate ocean island basalt-like signatures. Incompatible trace element ratios and isotopic ratios of the Pali Aike and Morro Chico lavas differ from those of the majority of Neogene southern Patagonian slab window lavas in showing more enriched characteristics and are similar to high-μ ( HIMU)-like basalts. The rare earth element ( REE) modeling to constrain mantle melting percentages suggests that these lavas were produced by low degrees of partial melting (1.0-2.0% for Pali Aike lavas and about 2.6-2.7% for Morro Chico lavas) of a garnet lherzolite mantle source. The major systematic variations of Sr- Nd- Pb isotopes in southern Patagonian lavas are related to geographic location. The Pali Aike and Morro Chico lavas from the southernmost part of Patagonia have lower 87 Sr/86 Sr and higher 143 Nd/144 Nd and 206 Pb/204 Pb ratios, relative to most of the southern Patagonian lavas erupted north of 49.5° S, pointing to a HIMU-like signature. An isotopically depleted and HIMU-like asthenospheric domain may have been the main source of magmas in the southernmost part of Patagonia (e.g. Pali Aike, Morro Chico, and Camusu Aike volcanic field), suggesting the presence of a major discontinuity in the isotopic composition of the asthenosphere in southern Patagonia. On the basis of geochemical and isotope data and the available geological and geotectonic reconstructions, a link between the HIMU asthenospheric mantle domain beneath southernmost Patagonia and the HIMU mega-province of the southwestern Pacific Ocean is proposed.
- Subjects
PACIFIC Ocean; ISOTOPES; PETROGENESIS; ANALYTICAL geochemistry; BASALT; MAGMAS
- Publication
Island Arc, 2012, Vol 21, Issue 4, p327
- ISSN
1038-4871
- Publication type
Article
- DOI
10.1111/iar.12002