CAJ | 학술논문

本文对越南西北部Phan Si Pan地区变质地体中的一个Ngoi Chi片麻岩进行了锆石CL内部结构分析、LA-(MC)-ICP-MS锆石U-Pb定年和Hf同位素分析。CL图象和Th/U比值特征显示该片麻岩样品中的锆石主要为岩浆锆石,有少量窄的变质边。岩浆锆石的年龄为~2.9 Ga,表明该样品是越南西北部Phan Si Pan地区的基底岩石。它们的εHf(t)值为–4.70±0.92,二阶段Hf模式年龄为~3.5 Ga,表明其为更古老的(>3.5 Ga)冥太古代地壳物质部分熔融作用形成。变质边部锆石给出了~1.8 Ga的年龄,表明变质作用发生在古元古代早期, Phan Si Pan地区在这一时期可能经历了一次重要的构造热事件。
본문대월남서북부Phan Si Pan지구변질지체중적일개Ngoi Chi편마암진행료고석CL내부결구분석、LA-(MC)-ICP-MS고석U-Pb정년화Hf동위소분석。CL도상화Th/U비치특정현시해편마암양품중적고석주요위암장고석,유소량착적변질변。암장고석적년령위~2.9 Ga,표명해양품시월남서북부Phan Si Pan지구적기저암석。타문적εHf(t)치위–4.70±0.92,이계단Hf모식년령위~3.5 Ga,표명기위경고로적(>3.5 Ga)명태고대지각물질부분용융작용형성。변질변부고석급출료~1.8 Ga적년령,표명변질작용발생재고원고대조기, Phan Si Pan지구재저일시기가능경력료일차중요적구조열사건。
This paper reports the result of an integrated study of zircon U-Pb age and Hf isotope composition for a gneiss sample (Ngoi Chi formation) from the Phan Si Pan area in northwest Vietnam. CL imaging reveals that most zircons are magmatic, with a few of them exhibiting thin metamorphic rims. The magmatic zircons gave a weighted mean U-Pb age of ~2.9 Ga, indicating the gneiss is the basement rock in the Phan Si Pan area. They haveεHf(t) value of –4.70±0.92, and two-stage Hf model age of ~3.5 Ga, indicating that the gneiss was derived from partial melting of >3.5 Ga crustal rock. The metamorphic rims yielded an age of ~1.8 Ga, implying that the metamorphic event occurred in the Neoarchean era, which might have been also a major tectono-thermal event in the Phan Si Pan area.