Ocean-floor volcanism in the Lachlan Fold Belt: new evidence from the Wyalong area, New South Wales

Geochemical data indicate that a recently recognised sequence of Ordovician volcanic rocks (the Narragudgil Volcanics) south of Wyalong (NSW) accumulated in an oceanic environment, either
in a mid-ocean ridge (MORB) or back-arc basin (BAB) setting. These volcanics occur in the same package of highly magnetic rocks with a complex magnetic signature as the Gidginbung Volcanics, host to the Temora gold deposit. They were previously considered to be part of the Gidginbung Volcanics, although Warren et al. (1995: Cootamundra 1:250 000 Sheet Explanatory Notes, Geological Survey of New South Wales) noted the presence of rocks in this area as having "...affinities
to the older Jindalee Group with which they may be correlatable.

地球化学数据表明，新近在怀亚隆（Wyalong）以南的新南威尔士州（New South Wales, NSW）境内，识别出一套奥陶纪（Ordovician）火山岩序列——纳拉古吉尔火山岩（Narragudgil Volcanics），该套岩石形成于大洋环境，构造背景可能为洋中脊（mid-ocean ridge, MORB）或弧后盆地（back-arc basin, BAB）。该套火山岩与赋存特莫拉金矿床（Temora gold deposit）的吉丁本火山岩（Gidginbung Volcanics）同属一套具有复杂磁异常特征的强磁性岩石组合。此前，该套火山岩被划归为吉丁本火山岩的一部分，但沃伦等人（1995年：《库塔曼德拉1:25万图幅注释》，新南威尔士州地质调查局）指出，该区域内的岩石具有"与年代更老的金达利群（Jindalee Group）具有亲缘性，二者或可进行地层对比"。