Polyphase white mica growth in low-grade metapelites from La Cébila Metamorphic Complex (Famatinian Belt, Argentina): evidence from microstructural and XRD investigations
Two tectono-thermal metamorphic events, M1-D1 (S1, with associated white mica and chlorite: WM1-Chl1) and M2-D2 (S2, with development of WM2-Chl2), are established from polyphase white mica growth for low-grade units from the Ordovician metasedimentary successions of La Cébila Metamorphic Complex in...
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| Autores principales: | , , |
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| Lenguaje: | English |
| Publicado: |
Servicio Nacional de Geología y Minería (SERNAGEOMIN)
2011
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062011000200002 |
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| Sumario: | Two tectono-thermal metamorphic events, M1-D1 (S1, with associated white mica and chlorite: WM1-Chl1) and M2-D2 (S2, with development of WM2-Chl2), are established from polyphase white mica growth for low-grade units from the Ordovician metasedimentary successions of La Cébila Metamorphic Complex in the Famatinian belt (western-central Argentina). The thermobarometric characterization of the M1 main event was carried out by means of clay-mineral analysis and crystallo-chemical parameter measurements. Epizonal (temperatures between 300 and 400°C) and low-pressure conditions are suggested for M1 event, based in Kübler index values ranging from 0.23 to 0.17 A°20, white mica b parameter values between 9.004 and 9.022 Á (mean of 9.014 Á, n=16) and Si contents between 3.13-3.29 a.p.f.u. Temperatures of ~180-270°C are estimated for the M2 event, with Kübler index values ranging from 0.31 to 0.46 A°20. The M1-D1 event of La Cébila could be linked to high-strain heating tectono-metamorphic Ordovician regime recorded in others complexes from Famatinian foreland region of Sierras Pampeanas. |
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