Geochemical and isotopic constraints on the petrogenesis of granitoids from the Dalat zone, southern Vietnam

Détails

ID Serval
serval:BIB_DD6E2A43C17A
Type
Article: article d'un périodique ou d'un magazine.
Collection
Publications
Titre
Geochemical and isotopic constraints on the petrogenesis of granitoids from the Dalat zone, southern Vietnam
Périodique
Journal of Asian Earth Sciences
Auteur(s)
Thuy N.T.B., Satir M., Siebel W., Vennemann T.W., Van Long T.
ISSN-L
1367-9120
Statut éditorial
Publié
Date de publication
2004
Peer-reviewed
Oui
Volume
23
Pages
467-482
Langue
anglais
Résumé
Late Mesozoic granitoids of the Dalat zone are of sub-alkaline affinity,
belong to the high-K calc-alkaline series and display features typical
of I-type granites. The Dinhquan suite consists of hornblende-biotite
granodiorites, diorites, and minor granites emplaced at similar to110
My. These rocks have relatively low initial Sr-87/Sr-86 ratios
(0.7049-0.7061) and moderate epsilon(Nd(T)) values (-0.8 to -2.0).
Chondrite-normalized REE patterns are fractionated and have small
negative Eu anomalies (Eu/Eu* = 0.55-0.97). All these characteristics,
combined with low Al2O3/(FeO + MgO + TiO2) and (Na2O + K2O)/(FeO + MgO +
TiO2) ratios and high Mg# values, suggest an origin through dehydration
melting of alkaline mafic lower crustal source rocks. The Cana suite
contains biotite-bearing granites poor in hornblende. The rocks are
96-93 My old in age, having higher initial Sr-87/Sr-86 ratios
(0.7060-0.7064) and nearly constant epsilon(Nd(T)) (- 2.5 to - 2.7)
values. These characteristics, in conjunction with the chemical
signatures and old T-DM model ages, indicate that crustal material
played a very important role in their petrogenesis. The granites are
further characterized by strong negative Eu anomalies (Eu/Eu* =
0.04-0.39) and Sr, suggesting melting with residual plagioclase and/or a
high degree of fractional crystallization. The Deoca suite is made up of
92-88 My old pink porphyritic hornblende-biotite-bearing granodiorites,
monzogranites and diorites. Initial isotopic compositions (Sr-87/Sr-86 =
0.7055-0.7069; epsilon(Nd(T)) = +0-9 to -3.3) and chemical features
suggest derivation by dehydration melting of heterogeneous
metagreywacke-type sources with additional input of mantle-derived
material. Furthermore, the Deoca rocks have concave-upward REE patterns
indicating that amphibole played a dominant and garnet an insignificant
role during magma segregation. (C) 2003 Elsevier Ltd. All rights
reserved.
Création de la notice
29/09/2012 16:23
Dernière modification de la notice
20/08/2019 16:02
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