Colloform sulphide veins of Port au Port peninsula, Newfoundland
Colloform sulphide veins of Port au Port peninsula, Newfoundland
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DOI：
10.2113/gsecongeo.38.8.621
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发表时间：
1943-12
期刊：
影响因子：
5.8
通讯作者：
K. D. Watson
中科院分区：
文献类型：
--
作者：
K. D. Watson
在纽芬兰西南部欧港半岛的固特异展望，狭窄、透镜状、扭曲的矿脉占据着突出的垂直节理，这些节理平行于奥陶系石灰岩中宽阔背斜的轴线。富含方解石的脉石具有良好的梳状结构。方铅矿是最丰富的硫化物，主要以近平行的、拉长的立方体生长形式存在，其取向为垂直于矿脉带状的三角轴线。硫化锌主要以胶状细粒闪锌矿的形式赋存，呈棕色闪锌矿，具有垂直于条带的刀片结构。高指数浸泡介质中发现纤锌矿。白铁矿多呈同心条带、放射状纤维结构的结节状产出。列举了一种反常品种的铁铁矿的性质。少量黄铁矿一般与白铁矿共生。X-射线分析表明，矿化过程中产出的细小黑粉主要为铁灰石。提出了原生矿物的共生关系，认为矿石中的黄铁矿和黄铁矿、闪锌矿和纤锌矿空间组合密切，基本上是同生共生的，矿床形成于上密西西比晚期低温高压条件下。硫化物的几个结构特征表明胶体现象的重要性。虽然在矿床附近没有侵入岩，但纽芬兰的一些地方出现了后上古生代的火成岩。
At the Goodyear Prospect on the Port au Port peninsula in southwestern Newfoundland, narrow, lenticular, crustified veins occupy prominent vertical joints which strike parallel to the axis of a broad anticline in Ordovician limestone. The abundant calcite gangue exhibits excellent comb structure. Galena, the most plentiful sulphide, occurs mainly as subparallel, elongate growths of cubes oriented with trigonal axes normal to the banding of the veins. Zinc sulphide occurs principally as finely colloform-banded, brown sphalerite with bladed structure normal to the banding. An immersion medium of high index revealed wurtzite. Marcasite commonly occurs as nodules displaying concentric banding and radial fibrous structure. Properties of an anomalous variety of marcasite are listed. Pyrite in small amounts is generally associated with marcasite. Fine black powder occurring in marcasite nodules was shown by X-ray to be mainly marcasite. The paragenesis of the primary minerals is given; pyrite and marcasite, and, sphalerite and wurtzite which occur in close spatial association in the ore are believed to be essentially contemporaneous.Evidence is presented that the ores were deposited in post-upper Mississippian time under conditions of low temperature and pressure. Several textural features of the sulphides suggest the importance of colloidal phenomena. Although intrusives are unknown in the vicinity of the deposits, igneous rocks of post-upper Paleozoic age occur in a few places in Newfoundland.