Geochemical composition of sulfide and oxide minerals from ODP Sites 193-1188 and 193-1189, PACMANUS field@en

Ocean Drilling Program (ODP) Leg 193 recovered core from the active PACMANUS hydrothermal field (eastern Manus Basin, Papua New Guinea) that provided an excellent opportunity to study mineralization related to a seafloor hydrothermal system hosted by felsic volcanic rocks. The purpose of this work is to provide a data set of mineral chemistry of the sulfide-oxide mineralization and associated gold occurrence in samples drilled at Sites 1188 and 1189. PACMANUS consists of five active vent sites, namely Rogers Ruins, Roman Ruins, Satanic Mills, Tsukushi, and Snowcap. In this work two sites were studied: Snowcap and Roman Ruins. Snowcap is situated in a water depth of 1670 meters below sea level [mbsl], covers a knoll of dacite-rhyodacite lava, and is characterized by low-temperature diffuse venting. Roman Ruin lies in a water depth of 1693-1710 mbsl, is 150 m across, and contains numerous large, active and inactive, columnar chimneys. Sulfide mineralogy at the Roman Ruins site is dominated by pyrite with lesser amounts of chalcopyrite, sphalerite, pyrrhotite, marcasite, and galena. Sulfide minerals are relatively rare at Snow Cap. These are dominated by pyrite with minor chalcopyrite and sphalerite and traces of pyrrhotite. Native gold has been found in a single sample from Hole 1189B (Roman Ruins). Oxide minerals are represented by Ti magnetite, magnetite, ilmenite, hercynite (Fe spinel), and less abundant Al-Mg rich chromite (average = 10.6 wt% Al2O3 and 5.8 wt% MgO), Fe-Ti oxides, and a single occurrence of pyrophanite (Mn Ti O3). Oxide mineralization is more developed at Snowcap, whereas sulfide minerals are more extensive and show better development at Roman Ruins. The mineralogy was obtained mainly by a detailed optical microscopy study. Oxide mineral identifications were confirmed by X-ray diffraction, and mineral chemistry was determined by electron probe microanalyses.大洋钻探计划（Ocean Drilling Program, ODP）193航次从位于巴布亚新几内亚马努斯盆地东部的活跃PACMANUS热液场（PACMANUS hydrothermal field）获取了岩芯，为研究长英质火山岩宿主的海底热液系统相关矿化作用提供了绝佳契机。本数据集旨在提供1188和1189站位钻探样品中硫化物-氧化物矿化的矿物化学数据，以及伴生金的产出特征。PACMANUS热液场包含5个活动喷口位点，分别为罗杰斯废墟（Rogers Ruins）、罗马废墟（Roman Ruins）、撒旦磨坊（Satanic Mills）、筑紫（Tsukushi）与雪冠（Snowcap）。本研究仅针对其中两个位点开展：雪冠与罗马废墟。雪冠位点水深1670米（mbsl），坐落于英安流纹英安岩熔岩穹丘之上，以低温弥散喷流为典型特征。罗马废墟位点水深为1693~1710 mbsl，直径约150米，分布有大量活跃与休眠的柱状烟囱。罗马废墟位点的硫化物矿物组成以黄铁矿为主，伴生少量黄铜矿、闪锌矿、磁黄铁矿、白铁矿与方铅矿。雪冠位点的硫化物矿物相对稀少，同样以黄铁矿为主，仅含少量黄铜矿、闪锌矿以及微量磁黄铁矿。研究人员在1189B孔的单一样品中发现了自然金（native gold）。氧化物矿物包括钛磁铁矿（Ti magnetite）、磁铁矿（magnetite）、钛铁矿（ilmenite）、铁尖晶石（hercynite，Fe-spinel），以及含量较低的富铝镁铬铁矿（平均Al₂O₃含量为10.6 wt%，MgO含量为5.8 wt%）、铁钛氧化物（Fe-Ti oxides），还有一例红钛锰矿（MnTiO₃）产出。雪冠位点的氧化物矿化更为发育，而罗马废墟位点的硫化物矿物分布更广、发育程度更佳。本研究的矿物学数据主要通过详细的光学显微镜观测获得；氧化物矿物的鉴定通过X射线衍射（X-ray diffraction）得以验证，矿物化学组成则通过电子探针显微分析（electron probe microanalyses）测定。