Study on the chronology and trace element characteristics of skarn mineral in the Niukutou deposit, Qimantag region, Qinghai Province

doi:10.13745/j.esf.sf.2024.11.27

Abstract

Abstract:

The Niukutou deposit is a large-scale skarn Pb-Zn polymetallic deposit discovered in recent years in the Qimantag region, East Kunlun orogenic belt, Qinghai Province. The study of its mineralization age and ore genesis remains highly controversial. This paper presents a study of the porphyritic granite on the southwest side of the Niukutou M1 ore district and the associated skarn minerals. Through field research, LA-ICP-MS zircon U-Pb dating, and LA-ICP-MS mineral in-situ trace element analysis, this study aims to determine the chronology of the ore-related intrusion and the ore-forming ages of skarn minerals, reveal the physical and chemical conditions of mineralization, and further clarify the relationship between the evolution of ore-forming fluids and mineralization. LA-ICP-MS U-Pb geochronology results indicate that the porphyritic granite closely related to skarn on the southwest side of the Niukutou deposit was emplaced at (222.7±2.2) Ma, alignand the crystallization age of the associated garnet is 219 Ma. Both ages fall within the Late Triassic (Indosinian period), indicating Indosinian mineralization on the southwest side of the Niukutou deposit, distinct from the previously known Devonian event. Comprehensive field research and LA-ICP-MS mineral in-situ trace element analysis reveal a distinct skarn zonation sequence outward from the ore-forming intrusive: garnet skarn zone→hedenbergite skarn zone→(ilvaite-bearing) Mn-hedenbergite skarn zone→(ilvaite-bearing) johannsenite skarn zone. During the evolution of the ore-forming fluid, the REE patterns of these minerals change from LREE-enriched and HREE-depleted to LREE-depleted and HREE-enriched. Concurrently, δEu values, ΣREE contents, and U and Nd concentrations decrease. These geochemical trends indicate declining temperature and oxygen fugacity (f(O₂)), alongside increasing Mn content and pH of the fluid. The aforementioned changes in the physicochemical conditions of the ore-forming fluids resulted in the formation of a mineral assemblage comprising pyrrhotite, magnetite, chalcopyrite, and Mn-poor skarn minerals proximal to the ore-forming intrusive, whereas sphalerite, galena, and Mn-rich skarn minerals precipitated distal to it.

Key words: Late Triassic mineralization, U-Pb geochronology of zircon and garnet, LA-ICP-MS in-situ trace elements of skarn minerals, Qimantag

CLC Number:

WANG Xinyu, WANG Shulai, LIU Ming, ZHU Xinyou, LIU Jiajun, YANG Xinyu, WANG Huan, WANG Yuwang, WU Jinrong. Study on the chronology and trace element characteristics of skarn mineral in the Niukutou deposit, Qimantag region, Qinghai Province[J]. Earth Science Frontiers, 2025, 32(5): 326-344.

Figures/Tables 15

Fig.1 Regional geological and tectonic map of Qimantag belt (a) and Regional geological and mineral resources map of Qimantag belt (b). Modified after [4,7-8].

Fig.2 Geological sketch map of the Niukutou ore district

Fig.3 Geological profile of No.10 exploration line n in M1 magnetic anomaly area of Niukutou Ore district (location of profile A-A'is shown in Fig.2)

Fig.4 Geological map and skarn zoning plane map of the M1 section in Niukutou deposit (location is shown in Fig.2)

Fig.5 Hand specimens (a) and microscopic photos (b-d) of porphyritic granite in Niukutou ore district

Table 1 U-Pb isotopic compositions of porphyric granite

Fig.6 CL image (a), zircon covariance age curve (b), and weighted average (c) of porphyric granite in Niukutou deposit

Table 2 U-Pb compaston of garme from Ninkutu depositi

Fig.7 Tera-Wasserburg diagram of 207Pb-corrected 206Pb/238U age from garnet of the Niukutou deposit

Fig.8 Photo of hand specimens from main skarn minerals in Niukutou ore district

Fig.9 Microscopic photos of skarn minerals in Niukutou ore district

Table 3 The LA-ICP-MS imsiu mrcanalysis resuts of garnet, pyroxene and ivaite in the Niukutou deposit

Fig.10 Chondrite-normalized rare earth element (REE) distribution patterns for different generations of garnet (a, b), pyroxene (c, d), and ilvaite (e, f) from the Niukutou deposit. The chondrite-normalized values were calculated by [26].

Fig.11 Binary plots of (a) Y versus total rare earth element (∑REE), (b) Ho versus Y, (c) δEu versus ∑REE, (d) U versus ∑REE, (e) δCe versus ∑REE, and (f) δCe versus ∑REE in the Niukutou deposit

Fig.12 Profile showing the skarn zonation and evolution process of the ore-forming fluid in the Niukutou skarn deposit

References 54

[1]	毛景文, 周振华, 丰成友, 等. 初论中国三叠纪大规模成矿作用及其动力学背景[J]. 中国地质, 2012, 39(6): 1437-1471.
[2]	高永宝, 李文渊, 钱兵, 等. 东昆仑野马泉铁矿相关花岗质岩体年代学、地球化学及Hf同位素特征[J]. 岩石学报, 2014, 30(6): 1647-1665.
[3]	宋忠宝, 张雨莲, 贾群子, 等. 东昆仑祁漫塔格地区野马泉深部的华力西期花岗闪长岩U-Pb年龄及其意义[J]. 现代地质, 2014, 28(6): 1161-1169.
[4]	徐国端. 青海祁漫塔格多金属成矿带典型矿床地质地球化学研究[D]. 昆明: 昆明理工大学, 2010.
[5]	董云鹏, 惠博, 孙圣思, 等. 中国中央造山系原-古特提斯多阶段复合造山过程[J]. 地质学报, 2022, 96(10): 3426-3448.
[6]	丰成友, 赵一鸣, 李大新, 等. 青海西部祁漫塔格地区夕卡岩型铁铜多金属矿床的夕卡岩类型和矿物学特征[J]. 地质学报, 2011, 85(7): 1108-1115.
[7]	ZHONG S H, FENG C Y, SELTMANN R, et al. Geochemical contrasts between Late Triassic ore-bearing and barren intrusions in the Weibao Cu-Pb-Zn deposit, East Kunlun Mountains, NW China: constraints from accessory minerals (zircon and apatite)[J]. Mineralium Deposita, 2018, 53(6): 855-870.
[8]	王新雨, 王书来, 吴锦荣, 等. 青海省牛苦头铅锌矿床成矿时代研究: 来自成矿岩体年代学和黄铁矿Re-Os地球化学证据[J]. 西北地质, 2023, 56(6): 71-81.
[9]	王新雨, 祝新友, 李加多, 等. 青海牛苦头矿区两期岩浆岩及其夕卡岩型成矿作用[J]. 岩石学报, 2021, 37(5): 1567-1586.
[10]	姚磊, 吕志成, 赵财胜, 等. 青海祁漫塔格地区牛苦头矿床和卡而却卡矿床B区花岗质岩石LA-ICP-MS锆石U-Pb年龄: 对泥盆纪成岩成矿作用的指示[J]. 地质通报, 2016, 35(7): 1158-1169.
[11]	钟世华, 丰成友, 李大新, 等. 新疆维宝夕卡岩铜铅锌矿床维西矿段矿物学特征[J]. 地质学报, 2017, 91(5): 1066-1082.
[12]	赵子烨. 青海牛苦头矿床夕卡岩矿物学及成矿作用研究[D]. 北京: 中国地质大学(北京), 2019.
[13]	李加多, 王新雨, 祝新友, 等. 青海祁漫塔格海西期成矿初探: 以牛苦头M1铅锌矿床为例[J]. 矿产勘查, 2019, 10(8): 1775-1783.
[14]	罗攀, 吴锦荣, 张坤, 等. 牛苦头矿床矿石矿物标型特征及成因[J]. 矿产勘查, 2023, 14(6): 880-888.
[15]	王新雨, 祝新友, 李加多, 等. 青海牛苦头矿区锰质黑柱石成因及其地质意义[J]. 地质学报, 2020, 94(8): 2279-2290.
[16]	WANG X Y, WANG S L, ZHANG H Q, et al. Geochemical characteristics of the mineral assemblages from the niukutou Pb-Zn skarn deposit, East Kunlun Mountains, and their metallogenic implications[J]. Minerals, 2022, 13(1): 18.
[17]	SLÁMA J, KOŠLER J, CONDON D J, et al. Plešovice zircon: a new natural reference material for U-Pb and Hf isotopic microanalysis[J]. Chemical Geology, 2008, 249(1/2): 1-35.
[18]	LIU Y S, HU Z C, GAO S, et al. In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J]. Chemical Geology, 2008, 257(1/2): 34-43.
[19]	YANG Y H, WU F Y, YANG J H, et al. U-Pb age determination of schorlomite garnet by laser ablation inductively coupled plasma mass spectrometry[J]. Journal of Analytical Atomic Spectrometry, 2018, 33(2): 231-239.
[20]	WIEDENBECK M, ALLÉ P, CORFU F, et al. Three natural zircon standards for u-th-pb, lu-hf, trace element and ree analyses[J]. Geostandards Newsletter, 1995, 19(1): 1-23.
[21]	EGGINS S M, SHELLEY J M G. Compositional heterogeneity in NIST SRM 610-617 glasses[J]. Geostandards Newsletter: The Journal of Geostandards and Geoanalysis, 2002, 26: 269-286.
[22]	JOCHUM K P, WEIS U, STOLL B, et al. Determination of reference values for NIST SRM 610-617 glasses following ISO guidelines[J]. Geostandards and Geoanalytical Research, 2011, 35(4): 397-429.
[23]	WU S T, WÖRNER G, JOCHUM K P, et al. The preparation and preliminary characterisation of three synthetic andesite reference glass materials (ARM-1, ARM-2, ARM-3) for In situ microanalysis[J]. Geostandards and Geoanalytical Research, 2019, 43(4): 567-584.
[24]	PATON C, HELLSTROM J, PAUL B, et al. Iolite: freeware for the visualisation and processing of mass spectrometric data[J]. Journal of Analytical Atomic Spectrometry, 2011, 26(12): 2508-2518.
[25]	CHU G B, CHEN H Y, ZHANG S T, et al. Geochemistry and geochronology of multi-generation garnet: new insights on the genesis and fluid evolution of prograde skarn formation[J]. Geoscience Frontiers, 2023, 14(1): 101495.
[26]	SUN S S, MCDONOUGH W F. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[J]. Geological Society, London, Special Publications, 1989, 42(1): 313-345.
[27]	李光明, 沈远超, 刘铁兵. 东昆仑祁漫塔格地区华力西期花岗岩地质地球化学特征[J]. 地质与勘探, 2001, 37(1): 73-78.
[28]	丰成友, 王松, 李国臣, 等. 青海祁漫塔格中晚三叠世花岗岩: 年代学、地球化学及成矿意义[J]. 岩石学报, 2012, 28(2): 665-678.
[29]	刘建楠. 青海野马泉铁锌矿床多期次构造-岩浆热年代学成矿意义[D]. 北京: 中国地质科学院, 2018.
[30]	瞿泓滢, 丰成友, 裴荣富, 等. 青海祁漫塔格虎头崖多金属矿区岩体热年代学研究[J]. 地质学报, 2015, 89(3): 498-509.
[31]	于淼, 丰成友, 保广英, 等. 青海尕林格铁矿床夕卡岩矿物学及蚀变分带[J]. 矿床地质, 2013, 32(1): 55-76.
[32]	丰成友, 李东生, 屈文俊, 等. 青海祁漫塔格索拉吉尔夕卡岩型铜钼矿床辉钼矿铼-锇同位素定年及其地质意义[J]. 岩矿测试, 2009, 28(3): 223-227.
[33]	何书跃, 李东生, 李良林, 等. 青海东昆仑鸭子沟斑岩型铜(钼)矿区辉钼矿铼-锇同位素年龄及地质意义[J]. 大地构造与成矿学, 2009, 33(2): 236-242.
[34]	周建厚, 丰成友, 王辉, 等. 新疆祁漫塔格于沟子铁多金属矿辉钼矿Re-Os年龄及其地质意义[J]. 地质与勘探, 2014, 50(1): 1-7.
[35]	于淼, 丰成友, 刘洪川, 等. 青海尕林格夕卡岩型铁矿金云母⁴⁰Ar/³⁹Ar年代学及成矿地质意义[J]. 地质学报, 2015, 89(3): 510-521.
[36]	陈博, 张占玉, 耿建珍, 等. 青海西部祁漫塔格山卡尔却卡铜多金属矿床似斑状黑云二长花岗岩LA-ICP-MS锆石U-Pb年龄[J]. 地质通报, 2012, 31(增刊1): 463-468.
[37]	谌宏伟, 罗照华, 莫宣学, 等. 东昆仑喀雅克登塔格杂岩体的SHRI MP年龄及其地质意义[J]. 岩石矿物学杂志, 2006, 25(1): 25-32.
[38]	贾建团. 青海祁漫塔格地区牛苦头铁多金属矿床特征研究[D]. 北京: 中国地质大学(北京), 2013.
[39]	蒋成伍. 青海省格尔木市四角羊—牛苦头地区夕卡岩型铁多金属矿矿化特征及成矿模式研究[D]. 北京: 中国地质大学(北京), 2013.
[40]	DIETVORST E J L. Retrograde garnet zoning at low water pressure in metapelitic rocks from Kemiö, SW Finland[J]. Contributions to Mineralogy and Petrology, 1982, 79(1): 37-45.
[41]	FLYNN R T, WAYNE BURNHAM C. An experimental determination of rare earth partition coefficients between a chloride containing vapor phase and silicate melts[J]. Geochimica et Cosmochimica Acta, 1978, 42(6): 685-701.
[42]	PARK C, SONG Y, KANG I M, et al. Metasomatic changes during periodic fluid flux recorded in grandite garnet from the Weondong W-skarn deposit, South Korea[J]. Chemical Geology, 2017, 451: 135-153.
[43]	GASPAR M, KNAACK C, MEINERT L D, et al. REE in skarn systems: a LA-ICP-MS study of garnets from the Crown Jewel gold deposit[J]. Geochimica et Cosmochimica Acta, 2008, 72(1): 185-205.
[44]	WOOD S A. The geochemistry of rare earth elements and yttrium in geothermal waters[M]. Denver: Society of Economic Geologists, 2005: 133-158.
[45]	BAU M. Controls on the fractionation of isovalent trace elements in magmatic and aqueous systems: evidence from Y/Ho, Zr/Hf, and lanthanide tetrad effect[J]. Contributions to Mineralogy and Petrology, 1996, 123(3): 323-333.
[46]	ANDERS E, GREVESSE N. Abundances of the elements: meteoritic and solar[J]. Geochimica et Cosmochimica Acta, 1989, 53(1): 197-214.
[47]	BAU M. Rare-earth element mobility during hydrothermal and metamorphic fluid-rock interaction and the significance of the oxidation state of europium[J]. Chemical Geology, 1991, 93(3/4): 219-230.
[48]	SVERJENSKY D A. Europium redox equilibria in aqueous solution[J]. Earth and Planetary Science Letters, 1984, 67(1): 70-78.
[49]	XIAO X, ZHOU T F, WHITE N C, et al. The formation and trace elements of garnet in the skarn zone from the Xinqiao Cu-S-Fe-Au deposit, Tongling ore district, Anhui Province, eastern China[J]. Lithos, 2018, 302: 467-479.
[50]	VAN WESTRENEN W, ALLAN N L, BLUNDY J D, et al. Atomistic simulation of trace element incorporation into garnets: comparison with experimental garnet-melt partitioning data[J]. Geochimica et Cosmochimica Acta, 2000, 64(9): 1629-1639.
[51]	SMITH M P, HENDERSON P, JEFFRIES T E R, et al. The rare earth elements and uranium in garnets from the beinn an dubhaich aureole, Skye, Scotland, UK: constraints on processes in a dynamic hydrothermal system[J]. Journal of Petrology, 2004, 45(3): 457-484.
[52]	INGUAGGIATO C, CENSI P, ZUDDAS P, et al. Geochemistry of REE, Zr and Hf in a wide range of pH and water composition: the Nevado del ruiz volcano-hydrothermal system (Colombia)[J]. Chemical Geology, 2015, 417: 125-133.
[53]	MICHARD A. Rare earth element systematics in hydrothermal fluids[J]. Geochimica et Cosmochimica Acta, 1989, 53(3): 745-750.
[54]	KOLB J. The role of fluids in partitioning brittle deformation and ductile creep in auriferous shear zones between 500 and 700 ℃[J]. Tectonophysics, 2008, 446(1/2/3/4): 1-15.