Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that th...Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that the deposition of the supracrustal rocks occurred around 2 552-2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806±16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with relatively low intensity happened in the study area. it is speculated that a likely tectonic setting where the Jianping metamorphic complex formed is an active Continental margin that is involved in Continental collision and crustal thickening shortly after its formation.展开更多
北山南部地区敦煌岩群广泛分布着铁矿化磁铁石英岩,这些铁矿化磁铁石英岩沿片岩顺层分布,长度几米到一百多米不等,宽几十厘米到两米左右,浅灰色到肉红色,具强磁性。为了研究这种石英岩的成因,笔者对新疆与甘肃的交界处白山西南侧这套地...北山南部地区敦煌岩群广泛分布着铁矿化磁铁石英岩,这些铁矿化磁铁石英岩沿片岩顺层分布,长度几米到一百多米不等,宽几十厘米到两米左右,浅灰色到肉红色,具强磁性。为了研究这种石英岩的成因,笔者对新疆与甘肃的交界处白山西南侧这套地层的斜长角闪片岩中具有代表性的磁铁石英岩完整采集样品,样品具石英、磁铁矿、白云母、黑云母和绿泥石五种矿物,TFe为12.60%~12.70%。根据野外磁铁石英岩产出地质特征、室内显微镜薄片鉴定结果和电子探针检测各矿物特征,结合化学简项分析和岩石化学分析结果,发现本文研究的磁铁石英岩与国内外BIF(Banded iron formation)型磁铁石英岩不同,不具有沉积特征,可能为单纯变质成因。北山地区敦煌岩群这套古老变质地层可能经历了晚太古代、古元古代两次重要的变质事件,本文研究的铁矿化磁铁石英岩可能是在其中一次变质事件过程中形成的。这套变质地层是铁、铜、金等金属元素富集的含矿地层,具有极其重要的研究意义和找矿意义。展开更多
文摘Using the zircon Pb evaporation method and high precise ion microprobe analyses, zircon isotopic ages in supracrustal magnetite quartzites from Jianping metamorphic complex have been obtained. The results show that the deposition of the supracrustal rocks occurred around 2 552-2 520 Ma and the peak of granulite facies metamorphism reached at about 2 487 Ma; about (1 806±16) Ma, i.e. Mid-Proterozoic, the other possible metamorphic event with relatively low intensity happened in the study area. it is speculated that a likely tectonic setting where the Jianping metamorphic complex formed is an active Continental margin that is involved in Continental collision and crustal thickening shortly after its formation.
文摘北山南部地区敦煌岩群广泛分布着铁矿化磁铁石英岩,这些铁矿化磁铁石英岩沿片岩顺层分布,长度几米到一百多米不等,宽几十厘米到两米左右,浅灰色到肉红色,具强磁性。为了研究这种石英岩的成因,笔者对新疆与甘肃的交界处白山西南侧这套地层的斜长角闪片岩中具有代表性的磁铁石英岩完整采集样品,样品具石英、磁铁矿、白云母、黑云母和绿泥石五种矿物,TFe为12.60%~12.70%。根据野外磁铁石英岩产出地质特征、室内显微镜薄片鉴定结果和电子探针检测各矿物特征,结合化学简项分析和岩石化学分析结果,发现本文研究的磁铁石英岩与国内外BIF(Banded iron formation)型磁铁石英岩不同,不具有沉积特征,可能为单纯变质成因。北山地区敦煌岩群这套古老变质地层可能经历了晚太古代、古元古代两次重要的变质事件,本文研究的铁矿化磁铁石英岩可能是在其中一次变质事件过程中形成的。这套变质地层是铁、铜、金等金属元素富集的含矿地层,具有极其重要的研究意义和找矿意义。
