Petrogenetic links between lepidolite-subtype aplite-pegmatite,aplite veins and associated granites at Segura (central Portugal) |
| |
| Authors: | Isabel Margarida Horta Ribeiro Antunes Ana Margarida Ribeiro Neiva João Manuel Farinha Ramos Paulo Bravo Silva Maria Manuela Vinha Guerreiro Silva Fernando Corfu |
| |
| Institution: | 1. Polytechnic Institute of Castelo Branco, 6001-909 Castelo Branco, Portugal;2. Department of Earth Sciences and Geosciences Centre, University of Coimbra, 3000-272 Coimbra, Portugal;3. LNEG National Laboratory of Energy and Geology, Apartado 1089, 4466-956 S. Mamede de Infesta, Portugal;4. Department of Geosciences, University of Oslo, PB1047, Blindern N-0316, Norway |
| |
| Abstract: | In the Segura area, Variscan S-type granites, aplite veins and lepidolite-subtype granitic aplite-pegmatite veins intruded the Cambrian schist-metagraywacke complex. The granites are syn D3. Aplite veins also intruded the granites. Two-mica granite and muscovite granite have similar ages of 311.0 ± 0.5 Ma and 312.9 ± 2.0 Ma but are not genetically related, as indicated by their geochemical characteristics and (87Sr/86Sr)311 values. They correspond to distinct pulses of magma derived by partial melting of heterogeneous metapelitic rocks. Major and trace elements suggest fractionation trends for: (a) muscovite granite and aplite veins; (b) two-mica granite and lepidolite-subtype aplite-pegmatite veins, but with a gap in most of these trends. Least square analysis for major elements, and modeling of trace elements, indicate that the aplite veins were derived from the muscovite granite magma by fractional crystallization of quartz, plagioclase, K-feldspar and ilmenite. This is supported by the similar (87Sr/86Sr)311 and δ18O values and the behavior of P2O5 in K-feldspar and albite. The decrease in (87Sr/86Sr)311 and strong increase (1.6‰) in δ18O from two-mica granite to lepidolite-subtype aplite-pegmatite veins, and the behaviors of Ca, Mn and F of hydroxylapatite indicate that these veins are not related to the two-mica granite. |
| |
| Keywords: | Aplites Lepidolite-subtype aplite-pegmatites Lepidolite Montebrasite Sn&ndash Nb&ndash Ta oxide minerals Parent granite Crystal fractionation |
| 本文献已被 ScienceDirect 等数据库收录！ |
|
