胡安·德富卡洋脊因代沃段热液黑烟囱体成矿物质来源:硫同位素的限制

选取胡安·德富卡洋脊(Juan de Fuca Ridge,JDFR)因代沃(Endeavour)段的17个热液黑烟囱体样品对其中的硫同位素进行分析测定,讨论了因代沃段热液活动区内黑烟囱体成矿的物质来源、将硫同位素数据与已发表的热液流体及硫化物数据耦合,并结合前人的成果得到如下认识:(1)因代沃段硫化物的硫同位素组成与其他无沉积物覆盖的洋脊硫化物硫同位素组成相似,然而其相比于南胡安·德富卡洋脊(South Juan de Fuca Ridge,SJFR)硫化物亏损重同位素;(2)结合前人研究成果,如果SJFR硫化物的硫全部来自基底玄武岩的淋洗与海水中的硫酸盐,那么因代沃段硫化物的硫可能有1%~3%来自沉积物的贡献,故提出因代沃段成矿系统中的硫来源主要来自基底玄武岩,同时伴随有少量海水硫酸盐来源及沉积物来源的硫加入;(3)将硫同位素数据与已发表的热液流体及硫化物数据进行耦合发现热液流体中的沉积物信号与硫化物中的硫可能来自不同的源,并提出沉积物端元可能位于下渗区。

Ore-forming matter sources of hydrothermal black smoker chimneys in the Endeavour segment of the Juan de Fuca Ridge: sulfur isotope constraints

Seventeen samples were collected from hydrothermal black smoker chimneys in the Endeavour segment of the Juan de Fuca Ridge, and were analyzed for sulfur isotope compositions.The ore-forming matter sources of hydrothermal black smoker chimneys were discussed, and the sulfur isotope data were coupled with the published data of hydrothermal fluid and sulfide.Summaries and /or conclusions are as follows.(1) Sulfide from the Endeavour segment has similar sulfur isotope range as that of other sediment-starving mid-ocean ridges, and heavy isotope is depleted when comparing with that of SJDFR (southern Juan de Fuca Ridge). Together with the previous results, it is considered that if sulfur in sulfide of SJDFR wholly comes from the leaching of basal basalts and sulfate in seawater,1%~3% sediment should contribute to sulfide in the Endeavour segment. Therefore, the sulfur sources for sulfide in the Endeavour segment are mainly from the leaching of basal basalts and minor from seawater and sediment. (2) Coupling the sulfur isotope data with the published data of hydrothermal fluid and sulfide, it is suggested that the sources for the sediment signal in hydrothermal fluid and sulfur in sulfide may be different, and it is proposed that the sediment end-member should be located in the recharge zone.