The University of Southampton
University of Southampton Institutional Repository

The role of fractional crystallization in the genesis of early syn-D3, tin-mineralized Variscan two-mica granites from the Carrazeda de Ansiães area, northern Portugal

The role of fractional crystallization in the genesis of early syn-D3, tin-mineralized Variscan two-mica granites from the Carrazeda de Ansiães area, northern Portugal
The role of fractional crystallization in the genesis of early syn-D3, tin-mineralized Variscan two-mica granites from the Carrazeda de Ansiães area, northern Portugal
A multiphase granitic complex (G1–G6) in the Carrazeda de Ansiães area, Central Iberian Zone, was emplaced during syn-kinematic stages of the Variscan orogeny, between 329.9 ± 0.8 Ma and 318.9 ± 1.9 Ma, as determined by ID-TIMS U–Pb on zircon and monazite. The complex intruded the metasedimentary Douro Group in a NW trending antiform formed during the D1 and D3 deformation phases, but was itself affected by ductile and brittle deformation. The granites have equal or higher amounts of muscovite than biotite, and contain surmicaceous enclaves and more rarely xenoliths, “schlieren” and microgranular enclaves. They are S-type, mainly alkaline-calcic and peraluminous with ASI ranging between 1.21 and 1.45 and normative corundum of 2.63–4.77%. They are enriched in LREE relatively to HREE, with negative Eu anomalies, (87Sr/86Sr)i = 0.7097–0.7159, ?Nd = ? 6.2 to ? 9.1, and ?18O = 10.96–11.81‰. Geochemical and isotopic characteristics show that granites G1, G2, G4 and G5 correspond to distinct pulses of magma formed by partial melting of heterogeneous metasedimentary material. Geochemical fractionation trends recorded by whole rocks and minerals permit to distinguish and model two fractional crystallization series G2–G3 and G5–G6, the latter also affected by crustal assimilation during fractionation. Granites G1, G2, G3 and G6 have ? 20 ppm Sn and G5 16 ppm Sn; they are also associated with mineralized Sn- and W-bearing quartz veins. Fractional crystallization was the responsible process for the increase in Sn content in granites from the series and their micas.
S-type granites, U–Pb zircon and monazite ages, Isotopic data, Fractional crystallization, Tin
0024-4937
177-191
Teixeira, R.J.S.
0f819b12-b467-4dc9-9c23-47193239c8bf
Neiva, A.M.R.
5e04fd56-df56-418e-bd3e-e5ba1b5defd7
Gomes, M.E.P.
8b8c6444-3f6c-4ea4-8606-21a9341d159e
Corfu, F.
e36e7120-d221-47be-b699-3706bc8be924
Cuesta, A.
b4881d22-765d-4dea-a1ec-e1d5db01052c
Croudace, I.W.
24deb068-d096-485e-8a23-a32b7a68afaf
Teixeira, R.J.S.
0f819b12-b467-4dc9-9c23-47193239c8bf
Neiva, A.M.R.
5e04fd56-df56-418e-bd3e-e5ba1b5defd7
Gomes, M.E.P.
8b8c6444-3f6c-4ea4-8606-21a9341d159e
Corfu, F.
e36e7120-d221-47be-b699-3706bc8be924
Cuesta, A.
b4881d22-765d-4dea-a1ec-e1d5db01052c
Croudace, I.W.
24deb068-d096-485e-8a23-a32b7a68afaf

Teixeira, R.J.S., Neiva, A.M.R., Gomes, M.E.P., Corfu, F., Cuesta, A. and Croudace, I.W. (2012) The role of fractional crystallization in the genesis of early syn-D3, tin-mineralized Variscan two-mica granites from the Carrazeda de Ansiães area, northern Portugal. Lithos, 153, 177-191. (doi:10.1016/j.lithos.2012.04.024).

Record type: Article

Abstract

A multiphase granitic complex (G1–G6) in the Carrazeda de Ansiães area, Central Iberian Zone, was emplaced during syn-kinematic stages of the Variscan orogeny, between 329.9 ± 0.8 Ma and 318.9 ± 1.9 Ma, as determined by ID-TIMS U–Pb on zircon and monazite. The complex intruded the metasedimentary Douro Group in a NW trending antiform formed during the D1 and D3 deformation phases, but was itself affected by ductile and brittle deformation. The granites have equal or higher amounts of muscovite than biotite, and contain surmicaceous enclaves and more rarely xenoliths, “schlieren” and microgranular enclaves. They are S-type, mainly alkaline-calcic and peraluminous with ASI ranging between 1.21 and 1.45 and normative corundum of 2.63–4.77%. They are enriched in LREE relatively to HREE, with negative Eu anomalies, (87Sr/86Sr)i = 0.7097–0.7159, ?Nd = ? 6.2 to ? 9.1, and ?18O = 10.96–11.81‰. Geochemical and isotopic characteristics show that granites G1, G2, G4 and G5 correspond to distinct pulses of magma formed by partial melting of heterogeneous metasedimentary material. Geochemical fractionation trends recorded by whole rocks and minerals permit to distinguish and model two fractional crystallization series G2–G3 and G5–G6, the latter also affected by crustal assimilation during fractionation. Granites G1, G2, G3 and G6 have ? 20 ppm Sn and G5 16 ppm Sn; they are also associated with mineralized Sn- and W-bearing quartz veins. Fractional crystallization was the responsible process for the increase in Sn content in granites from the series and their micas.

Full text not available from this repository.

More information

Published date: 2012
Keywords: S-type granites, U–Pb zircon and monazite ages, Isotopic data, Fractional crystallization, Tin
Organisations: Geochemistry

Identifiers

Local EPrints ID: 348020
URI: http://eprints.soton.ac.uk/id/eprint/348020
ISSN: 0024-4937
PURE UUID: b96f4d7f-68ac-40bd-99e4-a11bdad3787d

Catalogue record

Date deposited: 05 Feb 2013 13:46
Last modified: 16 Jul 2019 21:44

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of http://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×