论文部分内容阅读
加利福尼亚海岸山脉北部的Franciscan杂岩和Great Valley岩系中的热泉和冷泉,流出含盐度为几个重量百分比、并富含D和墙~(18)O的水,尽管过去有人分别描述过这些水,并称之为“变质水”、“原生水”和“蛇纹石化流体”。而我们这次的研究表明,这些热泉和冷泉具有同一补给水,即为捕获的白垩纪海水,这种海水已经各种反应发生了变化。该区是了解地下水的混溶性和了解变质流体源、油田水和矿质迁移问题等重要的实例。该地下水中的δ~(34)S值具一定变动范围,有的接近海相硫酸盐值(+20％),δ~(13)C接近海相方解石值(0％)。泉水中锶同位素特征源于Great Valley岩系(~(87)~(86)Sr/~(86)Sr值约为0.705)。富盐泉水池与见白色细粒沉淀物的蛇纹石相物质成排并列产出,其pH值为11。部分地下水被加热、还原,并将Au、Ag、Sb、As和Hg迁移至地表(热泉沉淀物中金品位从小于1×10~(-6)到大于10×10~(-6)。这些经加热水的化学和同位素特征,与附近McLaughlin金矿床所发现金矿化流体相似。热泉沉淀出黄铁矿、自然硫,其方解石呈过饱和态。其它一些泉盐度较低,呈氧化态冷泉,为热泉流体的稀释相。它们不携带金属元素,但其硅和方解石均呈过饱和态。泉中气体中的~3He/~4He值均高于大气中的值,表明可能含有岩浆组分,这与Clear Lake的第四纪火山活动的存在相一致。~(129)I值指示为源于60～80Ma以前的水中碘化物,这与源流体的原生特征相符。
The Franciscan complex and the hot springs and cold springs in the northern part of the California Coastal Ranges flow out of saltwater with several percentages of salinity and are rich in D and 18-18 O, although some have been described These water, and called “metamorphic water”, “primary water” and “serpentine fluid.” Our current study shows that these hot springs and cold springs have the same make-up water, that is, the Cretaceous sea water captured, which has been altered by a variety of reactions. This area is an important example for understanding the miscibility of groundwater and for understanding the sources of metamorphic fluids, the problems of oil and water and mineral migration. The δ ~ (34) S value of the groundwater fluctuates within a certain range, some of them are close to the marine sulfate value (+20%) and δ ~ (13) C is close to the marine calcite value (0%). The strontium isotope in spring water is derived from the Great Valley series (~ (87) ~ (86) Sr / ~ (86) Sr is ~ 0.705). The salt-rich spring pool appears in parallel with the serpentine phase of white fine sediment with a pH of 11. Some of the groundwater is heated and reduced, and Au, Ag, Sb, As and Hg migrate to the surface (hot springs sediment gold grade from less than 1 × 10 -6 to more than 10 × 10 -6. The chemical and isotopic characteristics of these heated waters are similar to the gold mineralized fluids found in the nearby McLaughlin Gold Deposit. Hot springs precipitate pyrite, natural sulfur and their calcite is supersaturated, while others have lower salinity, Oxidative cold springs, which are dilute phases of hot spring fluids, do not carry metallic elements but have both supersaturated silicon and calcite. The ~ 3He / ~ 4He values in the spring gas are above atmospheric values, indicating that Containing magmatic components, consistent with the Quaternary volcanic activity of Clear Lake.The ~ (129) I value indicates iodide in water from 60-80 Ma, consistent with the primary characteristics of source fluids.