Metamorphism and tectonic evolution of paired metamorphic belt of Tanumé and Pichilemu regions, Chilean Coastal Cordillera, VI region

• Grant number: 12/17635-6
• Support Opportunities: Scholarships abroad - Research Internship - Doctorate
• Start date: January 10, 2013
• End date: January 09, 2014
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geology
• Principal Investigator: Caetano Juliani
• Grantee: Thaís Nogueira Hyppolito
• Supervisor: Antonio García Casco
• Host Institution: Instituto de Geociências (IGC). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: Universidad de Granada (UGR), Spain
• Associated to the scholarship: 10/11954-7 - Metamorphism and tectonic evolution of the paired metamorphic belt at Tanumé and Pichilemu regions, Chilean Coastal Cordillera, VI Region, BP.DR

Abstract

The metamorphic basement of Central Chile comprises a paired metamorphic belt which is divided into two series: a high pressure (HP)-low temperature (LT) series (Western Series) and a low pressure (LP)-high temperature one (Eastern Series). The rocks from the HP-LT series record the metamorphic conditions attained during the subduction of an oceanic crust beneath the southwestern margin of Gondwana in the Paleozoic era. The rocks from the LP-HT series, which occupied the shallower levels of the accretionary prism, exhibit metamorphic features of been affected by the emplacement of granitic and granodioritic plutons from the coeval magmatic arc. The main lithotypes comprising the Western Series in the Pichilemu region are blueschists and isofacial greenschists, high pressure greenschists, quartzofeldspathic schists with muscovite and chlorite, amphibolites and garnet-quartz mica schists. In the Eastern Series outcrop quartzofeldspathic schists with muscovite, chlorite and biotite, in the Pichilemu region. Further north, in the Tanumé beach, outcrop quartzofeldspathic schists with muscovite, biotite and garnet; and quartzofeldspathic schists with muscovite, biotite, staurolite and andalusite.Thermobarometric studies on blueschists and greenschists, considering the role played by the bulk chemical composition in the formation of blueschist mineral assemblage and isofacial greenschists, and on the rocks formed beneath a hot mantle wedge (amphibolites and garnet-quartz micaschists) aim to define the P-T-t-d metamorphic paths and the tectonic-metamorphic evolution of the subduction zone. The whole-rock geochemistry studies on high-pressure metabasites and the characterization of their paleotectonic setting will allow the reconstruction of the depositional environment and the tectonic accretionary margin, developed in the permo-carboniferous margin of the southwestern Gondwana.Additionally, the metamorphic characterization of metapelites that outcrop in the Tanumé region (LP-HT) will contribute to the understanding of the tectonic-metamorphic evolution of the paired metamorphic belt in the Pichilemu region. (AU)

Scientific publications

(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)

HYPPOLITO, T.; GARCIA-CASCO, A.; JULIANI, C.; MEIRA, V. T.; HALL, C.. Late Paleozoic onset of subduction and exhumation at the western margin of Gondwana (Chilenia Terrane): Counterclockwise P-T paths and timing of metamorphism of deep-seated garnet-mica schist and amphibolite of Punta Sirena, Coastal Accretionary Complex, central Chile (34 degrees S). LITHOS, v. 206, p. 409-434, OCT 2014. (12/01191-1, 12/17635-6, 10/11954-7)

HYPPOLITO, T.; JULIANI, C.; GARCIA-CASCO, A.; MEIRA, V.; BUSTAMANTE, A.; HALL, C.. LP/HT metamorphism as a temporal marker of change ofdeformation style within the Late Palaeozoic accretionary wedge of central Chile. JOURNAL OF METAMORPHIC GEOLOGY, v. 33, n. 9, p. 1003-1024, DEC 2015. (12/01191-1, 12/17635-6, 10/11954-7)

HYPPOLITO, THAIS; JULIANI, CAETANO; GARCIA-CASCO, ANTONIO; MEIRA, VINICIUS TIEPPO; BUSTAMANTE, ANDRES; HERVE, FRANCISCO. The nature of the Palaeozoic oceanic basin at the southwestern margin of Gondwana and implications for the origin of the Chilenia terrane (Pichilemu region, central Chile). INTERNATIONAL GEOLOGY REVIEW, v. 56, n. 9, p. 1097-1121, 2014. (12/01191-1, 12/17635-6, 10/11954-7)