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Geochemical and isotopic constraints on the petrogenesis of granitoids from the Dalat zone, southern Vietnam
| Content Provider | Semantic Scholar |
|---|---|
| Author | Thuy, Nguyen Satır, Muharrem Siebel, Wolfgang Vennemann, Torsten Walter Long, Trinh Van |
| Copyright Year | 2004 |
| Abstract | Abstract 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 ∼110 My. These rocks have relatively low initial 87 Sr/ 86 Sr ratios (0.7049–0.7061) and moderate e 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 Al 2 O 3 /(FeO+MgO+TiO 2 ) and (Na 2 O+K 2 O)/(FeO+MgO+TiO 2 ) 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 87 Sr/ 86 Sr ratios (0.7060–0.7064) and nearly constant e 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 ( 87 Sr/ 86 Sr=0.7055–0.7069; e 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. |
| Starting Page | 467 |
| Ending Page | 482 |
| Page Count | 16 |
| File Format | PDF HTM / HTML |
| DOI | 10.1016/j.jseaes.2003.06.001 |
| Volume Number | 23 |
| Alternate Webpage(s) | https://homepages.uni-tuebingen.de//wolfgang.siebel/pdffiles/thuy_jaes.pdf |
| Alternate Webpage(s) | https://doi.org/10.1016/j.jseaes.2003.06.001 |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
