Petrology of granitoids in the White Tiger, Dragon oil field basement and adjacent areas of the Cửu Long Basin
Vũ Như Hùng, Trịnh Long
Based on materials of quantitative study on the geology-structure side
and material composition of granitoids lying in the basement of White Tiger and
Dragon oil fields and adjacent areas of the
1. Type of post-collision continental margin arc magmas of T3-J1 age, including an association of differentiated from intermediate to felsic rocks closely related to activities of subduction zone, having deep origin from mantle strongly contaminated by the crust, with: IRSr = 0.70448; IRNd = 0.512207; εNd = -2.86, belonging to the I- S-granite type. Their isotopic age is 178±5 - 222±5 Ma..
2. Type of active continental margin arc magmas of K1 age, including an association of differentiated from mafic, intermediate to felsic rocks closely related to subduction zone settings. Behaviours of trace elements reflect that they took source from magmas of mantle partly mixed and contaminated by the crust. They have low IRSr (0.70645 - 0.70695); IRNd = 0.512309 - 0.512361; εNd = (-3.43) - (-1.92) with 147Sm/144Nd = 0.098 - 0.1238, showing that their magmas took source from enriched mantle with the somewhat contaminated and mixed tendency. Their isotopic age is 111±5 - 143,80 Ma..
3. Type of spreading on the continental margin arc magmas of
4. Type of anorogenic magmas of Paleogene age, including 2 bimodal associations: felsic (with IRSr = 0.70639; IRNd = 0.512532; eNd = -0.81), taking source from metasomatic mantle, rich in trace elements of EMII type, and mafic (with IRSr = 0.70614; IRNd = 0.512606; eNd = -0.23), taking source from mantle having the composition corresponding to homogenous chondrite source domain.
Người biên tập: GS.TS. Trần Văn Trị.