Behavior of volatile components and mechanism of ore formation in the magmatic-hydrothermal system

岩浆-热液系统挥发成分行为及成矿机制

基本信息

批准号：
12440143
负责人：
HAYASHI Ken-ichiro
金额：
$ 2.11万
依托单位：
Tohoku University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (B)
财政年份：
2000
资助国家：
日本
起止时间：
2000 至 2002
项目状态：
已结题

项目摘要

During the solidification of hydrous granitic magma, water of very high salinity separates from the magma. The magmatic water contains volatile components such as CO_2 and H_2S. Since concentration of dissolved metallic ions in magmatic water is rather high, it behaves as an ore-forming solution. In this study, ore deposits that have genetical relation with magmatic water are studied.The skarn-type magnetite deposit at the Beni Bou Ifrour mine, northeastem Morocco, is the one of the major iron deposits in northern Africa. The skarn ore develops between limestone and microgranodioritic intrusions. The genetical relationship between skarn and granodiorite has been argued. The result of K-Ar dating shows that age of skarn mineral is approximately same as that of granodiorite; this agreement suggests ore-forming solution of this deposit was magmatic water that derived from granodiorite. Data obtained from fluid inclusions show very high temperature, 〜500℃, and very high salinity, 〜75 wt% equivalent NaCl. Oxygen isotope values of skarn minerals suggest that water of magmatic origin precipitated skarn minerals. Therefore, magmatic water of high temperature and high salinity was responsible for the transport of large amount of iron during the formation of magnetite deposit.Oxygen isotope values of manganese silicate minerals from the metamorphosed bedded type manganese deposit at the Noda-Tamagawa mine, northeastern Japan, were analyzed. Since this manganese deposit is hosted in the roofpendant just above the granitic body, evidence of magmatic water probably recorded in manganese minerals. However, oxygen isotopic equilibrium has not been attained among manganese minerals of closely associated. This suggests that amount of metamorphic fluid during contact metamorphism has been very small.

在液态花岗岩岩浆的凝固过程中，盐度非常高的水与岩浆分离。岩浆水包含挥发性组件，例如CO_2和H_2S。由于岩浆水中溶解的金属离子的浓度相当高，因此它作为矿石形成溶液的表现。在这项研究中，与岩浆水有遗传关系的矿石沉积物是研究的。东北摩洛哥贝尼·布鲁尔矿（Beni Bou Ifrour）矿山的Skarn型磁铁矿沉积物是北非的主要铁矿矿床之一。 Skarn矿在石灰石和微畸形侵入之间发展。 Skarn和花岗岩之间的遗传关系已被争论。 K-AR约会的结果表明，Skarn矿物的年龄大致相同。该协议表明，该沉积物的矿石形成溶液是源自颗粒状的岩浆水。从流体夹杂物获得的数据显示出非常高的温度，〜500℃，盐度非常高，〜75 wt％等效的NaCl。 Skarn矿物质的氧同位素值表明岩浆起源的水沉淀出Skarn矿物质。因此，分析了高温和高盐度的岩浆水，负责在磁铁矿沉积物形成过程中大量铁的运输。分析了日本北川北川矿物质的变质层状型锰矿的锰硅矿物矿物质的氧同位素值。由于这种锰矿矿床位于花岗岩体上方的屋顶居民中，因此可能记录在锰矿物质中的岩浆水的证据。但是，在密切相关的锰矿物质中尚未获得氧同位素同位物质。这表明接触变质过程中的变质液数量很小。