Thermal conditions during deformation of partially molten crust from TitaniQ geothermometry: rheological implications for the anatectic domain of the Araçuaí belt, Eastern Brazil
| Autor: | Bernard Boyer, Alain Vauchez, Claude Merlet, Geane Carolina G. Cavalcante, Marcos Egydio-Silva, M. H. Bezerra de Holanda |
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| Přispěvatelé: | Géosciences Montpellier, Université des Antilles et de la Guyane (UAG)-Institut national des sciences de l'Univers (INSU - CNRS)-Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Universidade de São Paulo (USP) |
| Rok vydání: | 2014 |
| Předmět: |
010504 meteorology & atmospheric sciences
Stratigraphy Soil Science Mineralogy CROSTA DA TERRA Deformation (meteorology) 010502 geochemistry & geophysics 01 natural sciences law.invention Viscosity lcsh:Stratigraphy Geochemistry and Petrology law [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry Crystallization Petrology Quartz Chemical composition Earth-Surface Processes lcsh:QE640-699 0105 earth and related environmental sciences lcsh:QE1-996.5 Partial melting Paleontology Geology Crust Orogeny lcsh:Geology Geophysics 13. Climate action |
| Zdroj: | Solid Earth Solid Earth, European Geosciences Union, 2014, 5 (2), pp.1223-1242. ⟨10.5194/se-5-1223-2014⟩ Solid Earth, Vol 5, Iss 2, Pp 1223-1242 (2014) Repositório Institucional da USP (Biblioteca Digital da Produção Intelectual) Universidade de São Paulo (USP) instacron:USP |
| ISSN: | 1869-9510 1869-9529 |
| Popis: | During the Neoproterozoic orogeny, the middle crust of the Araçuaí belt underwent widespread partial melting. At the regional scale, this anatectic domain is characterized by a progressive rotation of the flow direction from South to North, suggesting a 3-D deformation of the anatectic middle crust. To better constrain whether melt volumes present in the anatectic middle crust of the Araçuaí orogen were large enough to allow a combination of gravity-driven and convergence-driven deformation, we used the titanium-in-quartz geothermometer (TitaniQ) to estimate the crystallization temperatures of quartz grains in the anatectic rocks. When possible, we compared these estimates with thermobarometric estimates from traditional exchange geothermobarometers applied to neighboring migmatitic kinzigites. TitaniQ temperatures range from 750 to 800 °C, suggesting that quartz start crystallizing at a minimum temperatures ≥800 °C. These results, combined with the bulk-rock composition of isolated leucosomes allow to estimate a minimum of ∼30% melt in the anatectic leucossomes and a corresponding viscosity of ∼109–110 Pa s. Such a minimum melt content and low viscosity are in agreement with interconnected melt networks observed in the field. Considering that these characteristics are homogeneous over a wide area, this supports that the strength of the middle crust was severely weaken by extensive partial melting turning it prone to gravity-driven channel flow and lateral extrusion. |
| Databáze: | OpenAIRE |
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