40Ar/39Ar GEOCHRONOLOGY OF SUPERGENE JAROSITE FROM LIUHUANGSHAN COPPER POLYMETALLIC DEPOSITS IN Tu-Ha BASIN AND THE ENLIGHMENT TO WEATHERING, LANDSCAPE EVOLUTION AND PALEOCLIMATE
-
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40Ar/39Ar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40Ar/39Ar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。Abstract: Supergene jarosite is widely distributed in oxidation zone of sulphide deposits in arid-semiarid area. Precise 40Ar/39Ar 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/39Ar laser incremental heating analysis of jarosite from the Liuhuangshan 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.
-
图 6 差异风化与侵蚀—斜坡后退模型示意图[30]
Figure 6. Diagram of differential weathering and erosion-scarp retreat model
表 1 硫磺山铜多金属矿床氧化带中三个表生黄钾铁矾激光加热40Ar/39Ar同位素分析结果
Table 1. 40Ar/39Ar laser incremental heating analysis results of the three jarosite samples from the Liuhuangshan deposit
加热阶段 激光功率/% 36Ar(a)/计数 37Ar(ca)/计数 38Ar(cl)/计数 39Ar(k)/计数 40Ar(r)/计数 年龄/Ma 误差(1σ)/Ma 40Ar(r)/% 39Ar(k)/% LHS-06 J=0.00220320±0.00000110 001 2.4 454038.5 0.0 2773.6 64247.1 13368103 682.38 ±7.08 9.06 2.65 002 3.0 233013.2 0.0 1335.2 101071.3 5619147 208.95 ±3.61 7.55 4.17 003 4.0 285811.6 0.0 1556.6 212203.0 7286304 131.87 ±1.62 7.94 8.75 004 4.5 155599.7 0.0 952.1 195338.1 3764719 75.20 ±1.59 7.57 8.06 005 5.0 152475.7 0.0 600.7 146294.8 3201065 85.14 ±1.49 6.63 6.04 006 5.5 128673.3 0.0 518.2 164419.9 3033754 72.06 ±0.97 7.39 6.78 007 6.0 115599.2 0.0 174.2 150989.6 2563535 66.41 ±2.10 6.98 6.23 008 7.0 * 95055.3 0.0 74.5 141718.1 1989293 55.08 ±1.05 6.61 5.85 009 7.0 * 96472.0 0.0 43.2 142632.5 1995717 54.90 ±1.13 6.54 5.88 010 7.5 * 85700.4 0.0 235.8 157629.8 2223797 55.35 ±0.88 8.07 6.50 011 8.0 * 87532.7 0.0 0.0 132210.7 1894615 56.21 ±0.41 6.82 5.45 012 8.5 * 64408.4 0.0 0.0 109467.6 1563441 56.02 ±0.85 7.59 4.52 013 9.0 * 74693.9 0.0 45.8 129864.5 1846148 55.77 ±0.43 7.72 5.36 014 9.5 * 74136.3 0.0 0.0 117584.8 1623559 54.19 ±0.81 6.90 4.85 015 10.0 * 73072.1 0.0 0.0 119674.2 1699412 55.71 ±0.72 7.30 4.94 016 11.0 * 62290.3 0.0 85.8 150716.4 2124124 55.30 ±0.94 10.35 6.22 017 12.0 * 81394.0 0.0 244.0 187740.6 2667237 55.73 ±0.92 9.98 7.75 LHS-10 J=0.00210794±0.00000105 001 2.0 161095.0 0.0 73.1 13429.8 2167823 529.59 ±18.15 4.36 0.50 002 2.5 550143.6 0.0 3864.9 183920.5 14972852 286.39 ±2.28 8.43 6.89 003 3.0 234508.2 0.0 831.2 149724.1 4128850 102.17 ±2.47 5.62 5.61 004 3.5 256799.3 0.0 1682.8 275988.8 5536562 74.90 ±1.35 6.80 10.34 005 4.0 * 195954.5 10988.0 1546.5 308577.1 3928528 47.89 ±0.44 6.35 11.56 006 4.5 * 225492.9 0.0 1415.3 318946.4 4079954 48.11 ±0.36 5.77 11.95 007 5.0 * 162256.9 0.0 714.9 218448.5 2815326 48.47 ±0.93 5.55 8.19 008 5.5 * 126834.7 809.1 903.0 196424.3 2537082 48.58 ±0.75 6.34 7.36 009 6.0 * 128162.5 0.0 891.1 198922.7 2677404 50.59 ±1.49 6.60 7.46 010 6.5 * 134377.2 0.0 1204.3 195851.6 2490028 47.82 ±0.51 5.90 7.34 011 7.0 * 109442.8 0.0 885.3 163467.0 2118509 48.74 ±0.61 6.15 6.13 012 8.0 * 146880.5 0.0 1208.9 215033.4 2726256 47.69 ±0.88 5.91 8.06 013 9.0 * 153847.8 0.0 1398.3 229536.7 2965634 48.59 ±1.16 6.12 8.60 LHS-09 J=0.00212410±0.00000106 001 2.4 142867.1 0.0 0.0 201530.6 2214895 41.73 ±1.00 4.98 5.96 002 3.0 38686.2 0.0 0.0 196007.1 1378179 26.81 ±0.53 10.76 5.79 003 4.0 24548.1 0.0 0.0 326348.3 2568306 29.98 ±0.23 26.15 9.65 004 4.5 22817.1 0.0 0.0 281584.3 2674856 36.12 ±0.23 28.40 8.32 005 5.0 * 20227.4 0.0 0.0 241377.7 2569248 40.43 ±0.31 30.06 7.14 006 6.0 * 21655.9 0.0 0.0 335786.0 3550995 40.17 ±0.19 35.69 9.93 007 7.0 * 27901.9 0.0 56.5 364837.3 3907132 40.67 ±0.40 32.15 10.79 008 8.0 * 15111.1 0.0 0.0 227155.5 2399218 40.12 ±0.21 34.95 6.72 009 9.0 * 14495.4 0.0 0.0 206766.8 2180267 40.06 ±0.31 33.73 6.11 010 10.0 * 11146.6 0.0 0.0 203458.7 2137178 39.90 ±0.20 39.35 6.01 011 11.0 * 12904.9 0.0 0.0 196015.9 2074971 40.21 ±0.42 35.24 5.79 012 12.0 * 10271.7 0.0 0.0 175183.3 1936765 41.97 ±2.31 38.95 5.18 013 13.0 * 12078.5 0.0 0.0 185073.3 1974840 40.53 ±0.20 35.62 5.47 014 15.0 * 12292.1 0.0 0.0 241450.1 2573258 40.48 ±0.18 41.46 7.14 表 2 三个表生黄钾铁矾40Ar/39Ar年龄结果
Table 2. Results of 40Ar/39Ar ages of three jarosite samples from Liuhuangshan deposit
样品 样品颗粒 坪年龄Age/Ma 反等时线年龄/Ma 40Ar/36Ar 说明 LHS-06 LHS-06-1 55.6±0.2 55.0±1.7 295.8±0.8 微小39Ar反冲, 坪年龄 LHS-10 LHS-10-1 48.2±0.2 48.6±4.3 295.3±1.8 微小39Ar反冲, 坪年龄 LHS-09 LHS-09-1 40.3±0.1 40.1±0.6 296.5±2.5 坪年龄 -
[1] Alpers C N, Brimhall G H. Middle Miocene climatic change in the Atacama Desert, northern Chile:evidence from supergene mineralization at La Escondida[J]. GSA Bulletin, 1988, 100(10):1640~1656. doi: 10.1130/0016-7606(1988)100<1640:MMCCIT>2.3.CO;2 [2] Clark A, Tosdal R, Farar E, et al. Geomorphologic environment and age of supergene enrichment of the Cuajone, Quellaveco, and Toquepala Porphyry Copper Deposits, Southeastern Peru[J]. Economic Geology, 1990, 85(7):1604~1628. doi: 10.2113/gsecongeo.85.7.1604 [3] Vasconcelos P M, Brimhall G H, Becker T, et al. 40Ar/39Ar analysis of supergene jarosite and alunite:implications to the paleoweathering history of western USA and West Africa[J]. Geochimica et Cosmochimica Acta, 1994, 58(1):401~420. doi: 10.1016/0016-7037(94)90473-1 [4] Vasconcelos P M. K-Ar and 40Ar/39Ar geochronology of weathering processes[J]. Annual Review of Earth and Planetary Sciences, 1999, 27(1):183~229. doi: 10.1146/annurev.earth.27.1.183 [5] Vasconcelos P M D. 40Ar/39Ar geochronology of supergene processes in ore deposits[A]. Lambert D, Ruiz J.Reviews in Economic Geology[M]. Chelsea, Michigan, USA:Society of Economic Geologists, 1999, 73~113. [6] Bird M I, Chivas A R, McDougall I. An isotopic study of surficial alunite in Australia2.Potassium-argon geochronology[J]. Chemical Geology:Isotope Geoscience Section, 1990, 80(2):133~145. doi: 10.1016/0168-9622(90)90022-5 [7] Arehart G B, O'Neil J R. Western U.S. continental climate record since 30 Ma as recorded in alunite:comparison with the marine record[A]. 1992 Annual Meeting of the Geological Society of America (GSA)[C]. Cincinnati, OH:Geological Society of America, 1992, 24:268. [8] Rye R O, Bethke P M, Lanphere M A. Age and stable isotopic systematics of supergene alunite and jarosite from the Creede mining district, Colorado:Implications for supergene processes and Neogene geomorphic evolution and climate of the southern Rocky Mountains[C]. Uinted States:Geological Society of America, 1993, 25:274. [9] Sillitoe R H, McKee B H. Age of supergene oxidation and enrichment in the Chilean porphyry copper province[J]. Economic Geology, 1996, 91(1):164~179. doi: 10.2113/gsecongeo.91.1.164 [10] Marsh T, Einaudi M, McWilliams M. 40Ar/39Ar geochronology of Cu-Au and Au-Ag mineralization in the Potrerillos District, Chile[J]. Economic Geology, 1997, 92(7/8):784~806. http://www.academia.edu/13072690/3_Geochronology_and_geodynamics_of_Late_Cretaceous_magmatism_and_Cu_Au_mineralization_in_the_Panagyurishte_region_of_the_Apuseni_Banat_Timok_Srednogorie_belt_Bulgaria [11] Mote T I, Becker T A, Renne P, et al. Chronology of exotic mineralization at El Salvador, Chile, by 40Ar/39Ar dating of copper wad and supergene alunite[J]. Economic Geology, 2001, 96(2):351~366. doi: 10.2113/gsecongeo.96.2.351 [12] Bouzari F, Clark A H. Anatomy, evolution, and metallogenic significance of the supergene ore body of the Cerro Colorado Porphyry Copper Deposit, I Region, Northern Chile[J]. Economic Geology, 2002, 97(8):1701~1740. doi: 10.2113/gsecongeo.97.8.1701 [13] Quang C X, Clark A H, Lee J K W, et al. 40Ar/39Ar ages of hypogene and supergene mineralization in the Cerro Verde-Santa Rosa porphyry Cu-Mo cluster, Arequipa, Peru[J]. Economic Geology, 2003, 98(8):1683~1696. doi: 10.2113/gsecongeo.98.8.1683 [14] Quang C X, Clark A H, Lee J K W, et al. Response of supergene processes to episodic Cenozoic uplift, pediment erosion, and ignimbrite eruption in the porphyry copper province of southern Perú[J]. Economic Geology, 2005, 100(1):87~114. doi: 10.2113/100.1.0087 [15] Arancibia G, Matthews S J, Perez D A C. K-Ar and 40Ar/39Ar geochronologyof supergene processes in the Atacama Desert, Northern Chile:tectonic and climatic relations[J]. Journal of the Geological Society, 2006, 163(1):107~118. doi: 10.1144/0016-764904-161 [16] Vasconcelos P M, Conroy M. Geochronology of weathering and landscape evolution, Dugald River valley, NW Queensland, Australia[J]. Geochimica et Cosmochimica Acta, 2003, 67(16):2913~2930. doi: 10.1016/S0016-7037(02)01372-8 [17] 许英霞, 秦克章, 丁奎首, 等.东天山红山高硫型浅成低温铜金矿床:中生代成矿与新生代氧化的K-Ar、Ar-Ar年代学证据及其古构造和古气候意义[J].岩石学报, 2008, 24(10):2371~2383. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200810018.htmXU Ying-xia, QIN Ke-zhang, DING Kui-shou, et al. Geochronology evidence of Mesozoic metallogenesis and Cenozoic oxidation at Hongshan HS-epithermal Cu-Au deposit, Kalatage region, eastern Tianshan, and its tectonic and paleoclimatic significances[J]. Acta Petrologica Sinica, 2008, 24(10):2371~2383. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200810018.htm [18] 何为, 李大明, 郑德文, 等.东天山地区风化矿物黄钾铁矾的K-Ar测年及其环境意义[J].地震地质, 2009, 31(3):415~423. http://www.cnki.com.cn/Article/CJFDTOTAL-DZDZ200903004.htmHE Wei, LI Da-ming, ZHENG De-wen, et al. K-Ar dating of jarosite in the Eastern Tianshan and its environmental significance[J]. Seismology and Geology, 2009, 31(3):415~423. http://www.cnki.com.cn/Article/CJFDTOTAL-DZDZ200903004.htm [19] Yang J, Zheng D W, Li D M, , et al. 40Ar/39Ar analysis of supergene Yavapaiite and preliminary investigation on Ar closure temperature[J].Science China Earth Sciences, 2012, 55(12):1996~2004. doi: 10.1007/s11430-012-4491-3 [20] 杨静, 郑德文, 邱华宁, 等.吐哈地区表生黄钾铁矾40Ar/39Ar定年及其对晚中新世风化前锋拓展速率的限定[J].科学通报, 2014, 59(30):2956~2963.YANG Jing, ZHENG De-wen, QIU Hua-ning, et al. 40Ar/39Ar geochronology of supergene Jarosite constraints on weathering front propagation rate in the TuHabasin[J].Chinese Science Bulletin, 2014, 59(30):2956~2963. [21] Yang J, Zheng D W, Chen W, et al. 40Ar/39Ar geochronology of supergene K-bearing sulfate minerals:Cenozoic continental weathering and its paleoclimatic significance in the Tu-Ha Basin, northwestern China[J]. Palaeogeography, Palaeoclimatology, Palaeoecology, 2016, 445:83~96, doi: 10.1016/j.palaeo.2016.01.005. [22] 涂光炽, 李锡林.干旱和极端干旱气候条件下硫化物矿床氧化带发育特征(以西北五个矿床为例说明)[J].地质学报, 1963, 43(4):361~377. http://www.cnki.com.cn/Article/CJFDTOTAL-DZXE196304003.htmTU Guang-zhi, LI Xi-lin. Studies on the characteristic features of the oxidation zone of the sulphite deposits in arid to extremely arid regions:with special reference to observations obtained from five sulphide deposits in the Northwestern China[J]. Acta Geological Sinica, 1963, 43(4):361~377. http://www.cnki.com.cn/Article/CJFDTOTAL-DZXE196304003.htm [23] 方同辉, 秦克章, 王书来, 等.浅析卡拉塔格铜金矿成矿地质背景[J].矿床地质, 2002, 21(S):380~383. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ2002S1105.htmFANG Tong-hui, QIN Ke-zhang, WANG Shu-lai, et al. Elementary analysis of geological background ofKalatage copper and gold deposit[J]. Mineral Deposits, 2002, 21(S):380~383. http://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ2002S1105.htm [24] 秦克章, 方同辉, 王书来, 等.吐哈盆地南缘古生代"天窗"卡拉塔格铜金矿化区的发现及其成矿潜力[J].中国地质, 2001, 28(3):16~23. http://www.cnki.com.cn/Article/CJFDTOTAL-DIZI200103003.htmQIN Ke-zhang, FANG Tong-hui, WANG Shu-lai, et al. Discovery of the Kalatage Cu-Au mineralized district and its prospecting potentiality, Paleozoic window at the south margin of the Tu-Ha basin[J]. Geology in China, 2001, 28(3):16~23. http://www.cnki.com.cn/Article/CJFDTOTAL-DIZI200103003.htm [25] 秦克章, 丁奎首, 许英霞, 等.东天山红山Cu-Au矿床氧化带首次发现的副针绿矾巨晶及其多型针绿矾[J].岩石学报, 2008, 24(5):1112~1122. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200805018.htmQIN Ke-zhang, DING Kui-shou, XU Ying-xia, et al. Tremendous crystal-paraeoquimbite and its polytypecoquimbite found for the first time in Hongshan Hs-epithermal Cu-Au deposit, Eastern Tianshan, NW-China, and its significance[J]. Acta Petrologica Sinica, 2008, 24(5):1112~1122. http://www.cnki.com.cn/Article/CJFDTOTAL-YSXB200805018.htm [26] 李华芹, 陈富文.东天山硫磺山铜多金属矿床成岩成矿作用同位素地质年代学[J].地球学报, 2003, 24(6):555~558. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200306013.htmLI Hua-qin, CHEN Fu-wen. Rock-forming and ore-forming chronology of the Liuhuangshan copper-polymetallic deposit in East Tianshan Mountains[J]. Acta Geoscientica Sinica, 2003, 24(6):555~558. http://www.cnki.com.cn/Article/CJFDTOTAL-DQXB200306013.htm [27] 叶庆同, 吴一平, 傅旭杰, 等.西南天山金和有色金属矿床成矿条件和成矿预测[M].北京:地质出版社, 1999, 206.YE Qing-tong, WU Yi-ping, FU Xu-jie, et al. Ore-forming Conditions and Metallogenic Prognosis of Gold and Nonferrous Metallic Resources in Southwestern Tian shan Mountain[M]. Beijing:Geology Publishing House, 1999, 206. [28] Mc Dougall I, Harrison T M. Geochronology and Thermochronology by the 40Ar/39Ar method[M].2nd ed.New York:Oxford University Press, 1999, 269. [29] Koppers A P. ArArCALC-software for 40Ar/39Ar age calculations[J]. Computers & Geosciences, 2002, 28(5):605-619. http://www.academia.edu/13671358/Hydrothermal_fluids_argon_isotopes_and_mineralization_ages_of_the_Fankou_Pb_Zn_deposit_in_south_China_Insights_from_sphalerite_sup_40_sup_Ar_sup_39_sup_Ar_progressive_crushing [30] Vasconcelos P M D. Geochronology of weathering in the Mt Isa and Charters Towers regions, Northern Queensland[R]. Open File Reports 139.Leme:CRC, 2002. [31] 昝立宏, 程捷.新疆吐鲁番盆地古近纪气候事件的研究[J].古地理学报, 2008, 10(6):647~656. http://www.cnki.com.cn/Article/CJFDTOTAL-GDLX200806015.htmZAN Li-hong, CHENG Jie. Study on the Paleogene climatic events in the Turpan Basin, Xinjiang[J]. Journal of Palaeogeography, 2008, 10(6):647~656. http://www.cnki.com.cn/Article/CJFDTOTAL-GDLX200806015.htm [32] 程捷, 张秋营, 张西娟, 等.吐鲁番盆地新生代环境演变[M].北京:地震出版社, 2005, 122.CHENG Jie, ZHANG Qiu-ying, ZHANG Xi-juan, et al. Environmental Evolution During the Cenozoic in the Turpan Basin[M]. Beijing:Seismological Press, 2005, 122.