吐哈盆地硫磺山铜多金属矿床表生黄钾铁矾^(40)Ar/^(39)Ar定年及对风化、地貌演化及古气候的启示  

^(40)Ar/^(39)Ar GEOCHRONOLOGY OF SUPERGENE JAROSITE FROM LIUHUANGSHAN COPPER POLYMETALLIC DEPOSITS IN Tu-Ha BASIN AND THE ENLIGHMENT TO WEATHERING,LANDSCAPE EVOLUTION AND PALEOCLIMATE

作　　者：杨静[1] 郑德文[2] 陈文[3] 武颖[2] 许英霞 杨莉[3] 

机构地区：[1]中国地质科学院地质力学研究所,北京100081 [2]地震动力学国家重点实验室(中国地震局地质研究所),北京100029 [3]中国地质科学院地质研究所,北京100037 [4]华北理工大学矿业工程学院,唐山063009

出　　处：《地质力学学报》2017年第2期232-242,共11页Journal of Geomechanics

基　　金：国家自然科学基金项目(41403047;41272215);中国地质调查局地质调查项目"特殊地质地貌区填图试点(DD20160060)

摘　　要：黄钾铁矾是干旱—半干旱地区硫化物矿床氧化带中一种常见表生含钾硫酸盐矿物,对其进行^(40)Ar/^(39)Ar年代学研究,不仅可以直接限定硫化物矿床次生富集的时间,还可以为区域地貌形成演化和古气候演变等重大地质事件提供关键的年代学信息。本文对中国新疆吐哈盆地硫磺山铜多金属矿床氧化带中三个表生黄钾铁矾样品进行了^(40)Ar/^(39)Ar定年,第一次获得了始新世的风化矿物的年龄。结合已发表的年龄数据显示:在吐哈盆地,海拔较高的矿床氧化带剖面(如硫磺山矿床)记录了基岩的持续和较完整的区域风化事件,这些老的风化年龄的存在证明了剥蚀并不是均匀的,即其地貌演化遵循的是斜坡后退模型。对于吐哈盆地的古气候,这些表生硫酸盐的年龄表明:始新世以来吐哈盆地曾多次出现过有利于化学风化和硫化物矿床次生富集的干旱—半干旱气候,且主要集中在以下几个时期:27.7~23.3 Ma、16.4~14.7 Ma、11~7.8 Ma,之后气候开始向极端干旱气候转变,4.1~3.3 Ma之后吐哈盆地可能已经流行大规模的极端干旱气候。Supergene jarosite is widely distributed in oxidation zone of sulphide deposits in arid-semiarid area.Precise 40 Ar/39 Ar age constraints of supergene jarosite can not only define the timing of sulfide secondary enrichment, but also provide key information on the geochronology to the regional geomorphic evolution and paleoclimatic evolution. In this article, 40Ar/39 Ar laser incremental heating analysis of jarosite from theLiuhuangshan copper polymetallic deposit in Tu-Ha Basin is conducted, and the age of Eocene weathering mineral is defined for the first time. Combined with the published chronology data, it indicates that the profile of oxidation zone of ore deposit from the higher elevation sites recorded the more complete and lasting regional weathering events. The presence of ancient weathering ages in current outcrops in Tu-Ha Basin suggests that denudation was not homogeneous, and the landscape evolution followed a scarp retreat model. The ages in this present study and published ages demonstrate that chemical weathering and supergene enrichment under an arid-semiarid climate are mainly concentrated in the following period： 27. 7 -23. 3、16. 4 -14. 7、11 -7. 8 Ma. After the 11 -7. 8 Ma, a progressive change from arid-semiarid climate towards hyperarid climatic, and predominantly hyperarid climate may had persisted at least since 4. 1 -3. 3 Ma.

关 键 词：黄钾铁矾 40Ar/39Ar年代学 硫磺山铜多金属矿床 风化 地貌演化 古气候 

分 类 号：P597[天文地球—地球化学]