Exploration of concealed fluorite deposit in shallow overburden areas: A case study in Elimutai, Inner Mongolia, China

doi:10.13745/j.esf.sf.2021.1.7

Abstract

Abstract:

The Chifeng area in Inner Mongolia, China possesses a series of fracture-hosted hydrothermal vein-type fluorite deposits and is considered having a superior economic mineralization potential. In this study, we present an integrated prospecting approach integrating geological, geophysical, geochemical, and remote sensing techniques for exploration of concealed fluorite deposit in shallow overburden areas. The study area in Elimutai in the southern extension of the Shuitou fluorite belt, covered widely by Quarternary sediments, is ideal for such exploration. The fluorite orebodies in the study area show vertical zonation with, from top to bottom, distributions of silicified cap and head, main, and tail orebodies. The silicified cap in Elimutai is characterized by highly silicified breccia, secondary quartzite and quartz stockwork, whereas the head orebody contains fluorite vein. The outcrop of silicified cap is 30-50 m higher in latitude than the head orebody. The WorldView-2 remote sensing image reveals a linear distribution of ore-controlling fractures in the SN-striking northern/central segment and NNE-NE-striking southern segment. The results show the overlapping of mineralized outcrop, low-resistivity anomaly zone (by very low frequency electromagnetic (VLF-EM) analysis), positive Ca anomaly zone (by portable X-ray fluorescence (PXF) analysis), and positive F anomaly zone (by partial extraction geochemistry (PEG) analysis). The multi-anomalies can be used as indicator for the exploration and prediction of ore-controlling fractures and concealed fluorite orebody. In combination with VLF-EM mapping, the mineralized and altered outcrop zone overlaps with the SN-trending VLF low-resistivity anomaly zone, indicating the mineralization potential of the Elimutai area for concealed and semi-concealed fluorite. At the key prediction zone in Elimutai, the drill cores reveals the concealed fluorite ore well, exposing silicified cap, head orebody or narrow fractures. The overall evidence suggests that the deeper level of Elimutai is highly likely to contain the economically significant main fluorite orebody.

Key words: geological, geophysical, geochemical and remote sensing prospecting techniques, mineral resource prediction, concealed fluorite deposit, Elimutai, Inner Mongolia

CLC Number:

P62
P619.215

TANG Li, ZHANG Shouting, WANG Liang, PEI Qiuming, FANG Yi, CAO Huawen, ZOU Hao, YIN Shaobo. Exploration of concealed fluorite deposit in shallow overburden areas: A case study in Elimutai, Inner Mongolia, China[J]. Earth Science Frontiers, 2021, 28(3): 208-220.

Figures/Tables 11

Fig.1 (a) Simplified geological map of the southern Great Xing’an Range, and (b) geological map of the Shuitou fluorite belt in Linxi, Inner Mongolia. Modified after [3].

Fig.2 Geological map of Elimutai showing the prospecting lines

Fig.3 Representative field photos of the Elimutai area, featuring outcrops

Fig.4 WorldView-2 remote sensing image of the Elimutai area

Table 1 Physical properties of fluorite ore and wall rocks in the Linxi area

采样地点	岩性描述	样本数	密度/(g·cm^-3)	电阻率/(Ω·m)	极化率/%	磁性/(10^-5SI)
宝山	岩体内含萤石石英脉	2	2.38	2 909	8.44	10.0
水头南	石英脉	10	2.20	6 567	3.47	13.5
水头北	燧石角砾岩、石英脉	4	2.28	5 187	2.99
马岱沟	含矿带石英脉	2	2.04			5.0
宝山	白色结晶硅质岩	6	2.11	7 072	1.04
水头南	富萤石矿石	4	2.55	13 049	0.90
水头北	萤石矿石	8	2.52	1 264	1.59
马岱沟	角砾状矿石	1	2.29	778	6.11	65.0
马岱沟	萤石矿石	1	2.54	632	0.98
宝山	粗晶富矿石	5	2.50	3 824	4.01
宝山	绿帘石化中粗粒花岗岩	5	2.08	1 373	2.55	147
宝山	中粗粒花岗岩	6	2.07	975	5.20	272
马岱沟	半风化花岗岩	1	2.05			320
水头南	强硅化流纹斑岩	8	2.06	996	3.25	194
水头北	变砂岩	2	2.70	780	2.53	1 033
水头北	黑色碳质板岩	2	2.57	130	65.7	1 448

Fig.5 Planar mapping of low-resistivity anomaly zones by very low frequency electromagnetic (VLF-EM) measurements. Modified after [52].

Fig.6 Composite diagram showing, from top, F, Ca and low-resistivity anomaly profiles along the #10 prospecting line of Elimutai

Fig.7 Composite diagram showing, from top, F, Ca, and low-resistivity anomaly profiles along the #20 prospecting line of Elimutai

Fig.8 Vertical zonation model of fracture-hosted hydrothermal vein type fluorite orebody (modified after [57])

Fig.9 Superposition of geophysical (low-resistivity) and geochemical (F, Ca) anomaly measurements in the prediction zone of Elimutai

Fig.10 Examples of fluorite orebodies from the Elimutai drill core

References 60

[1]	李敬, 张寿庭, 商朋强, 等. 萤石资源现状及战略性价值分析[J]. 矿产保护与利用, 2019, 39(6):62-68.
[2]	王亮, 张寿庭, 裴秋明, 等. 内蒙古林西县小北沟萤石矿床流体包裹体特征[J]. 矿物学报, 2015(增刊1):500-501.
[3]	张寿庭, 曹华文, 郑硌, 等. 内蒙古林西水头萤石矿床成矿流体特征及成矿过程[J]. 地学前缘, 2014, 21(5):31-40.
[4]	陈武, 张寿庭, 张红亮. 对中国萤石矿开发利用问题的思考[J]. 资源与产业, 2014, 16(2):51-55.
[5]	陈石义, 张寿庭. 我国氟化工产业中萤石资源利用现状与产业发展对策[J]. 资源与产业, 2013, 15(2):79-83.
[6]	邹灏, 张寿庭, 方乙, 等. 中国萤石矿的研究现状及展望[J]. 国土资源科技管理, 2012, 29(5):35-42.
[7]	毛景文, 杨宗喜, 谢桂青, 等. 关键矿产:国际动向与思考[J]. 矿床地质, 2019, 38(4):689-698.
[8]	BERNHARDT D, REILLY I I. Mineral commodity summaries 2019[J]. US Geological Survey, Reston, USA, 2019: 42-43.
[9]	王自国, 朱培元. 中央企业萤石矿战略布局思考[J]. 中国矿业, 2020, 29(6):8-11.
[10]	方贵聪, 王登红, 陈毓川, 等. 南岭萤石矿床成矿规律及成因[J]. 地质学报, 2020, 94(1):161-178.
[11]	袁俊宏. 我国萤石资源开发利用情况[J]. 化工新型材料, 2005, 33(6):27-29.
[12]	王吉平, 朱敬宾, 李敬, 等. 中国萤石矿预测评价模型与资源潜力分析[J]. 地学前缘, 2018, 25(3):172-178.
[13]	孙月君. 内蒙古自治区萤石矿资源潜力评价[M]. 武汉: 中国地质大学出版社, 2018.
[14]	王吉平, 商朋强, 熊先孝, 等. 中国萤石矿床成矿规律[J]. 中国地质, 2015, 42(1):18-32.
[15]	HAN B, SHANG P, GAO Y, et al. Fluorite deposits in China: geological features, metallogenic regularity, and research progress[J]. China Geology, 2020, 3(3):473-489.
[16]	张彦生, 王亮, 高永璋. 内蒙古林西县水头萤石矿床地质特征、类型及其开发利用价值[J]. 中国地质, 2020. https://kns.cnki.net/kcms/detail/11.1167.P.20200805.1340.004.html
[17]	韩润生, 吴鹏, 王峰, 等. 论热液矿床深部大比例尺 “四步式” 找矿方法: 以川滇黔接壤区毛坪富锗铅锌矿为例[J]. 大地构造与成矿学, 2019, 43(2):246-257.
[18]	成秋明. 覆盖区矿产综合预测思路与方法[J]. 地球科学: 中国地质大学学报, 2012, 37(6):1109-1125.
[19]	赵鹏大. 成矿定量预测与深部找矿[J]. 地学前缘, 2007, 14(5):1-10.
[20]	陈毓川, 裴荣富, 王登红, 等. 矿床成矿系列: 五论矿床的成矿系列问题[J]. 地球学报, 2016, 37(5):519-527.
[21]	BEDINI E. Application of WorldView-3 imagery and ASTER TIR data to map alteration minerals associated with the Rodalquilar gold deposits, Southeast Spain[J]. Advances in Space Research, 2019, 63(10):3346-3357. DOI URL
[22]	刘怀金, 杨永强, 孙引强, 等. 内蒙古边家大院铅锌银多金属矿床原生晕地球化学特征及深部找矿预测[J]. 地质找矿论丛, 2016, 31(2):245-252.
[23]	谢学锦. 勘查地球化学的现状与未来展望[J]. 地质论评, 1996, 42(4):346-356.
[24]	卿成实, 彭秀红, 徐波, 等. 原生晕找矿法的研究进展[J]. 矿物学报, 2011(增刊1):828-829.
[25]	THABENG O L, MERLO S, ADAM E. High-resolution remote sensing and advanced classification techniques for the prospection of archaeological sites’ markers: the case of dung deposits in the Shashi-Limpopo Confluence area (southern Africa)[J]. Journal of Archaeological Science, 2019, 102:48-60. DOI URL
[26]	于汪, 王猛, 商朋强, 等. 地面高精度磁法在萤石矿勘查中的应用[J]. 地质学刊, 2019, 43(3):428-433.
[27]	夏炳卫, 曹华文, 裴秋明, 等. VLF-EM和EH4在浅覆盖区萤石矿床勘查中的应用: 以林西水头萤石矿区为例[J]. 桂林理工大学学报, 2016, 36(2):228-233.
[28]	PEI Q, ZHANG S, HAYASHI K, et al. Nature and genesis of the Xiaobeigou fluorite Deposit, Inner Mongolia, Northeast China: evidence from fluid inclusions and stable isotopes[J]. Resource Geology, 2019, 69(2):148-166. DOI URL
[29]	PEI Q, ZHANG S, SANTOSH M, et al. Geochronology, geochemistry, fluid inclusion and C, O and Hf isotope compositions of the Shuitou fluorite deposit, Inner Mongolia, China[J]. Ore Geology Reviews, 2017, 83:174-190. DOI URL
[30]	WANG L, TANG L, ZHANG S, et al. Genesis of the Yujiadian F-Pb-Zn-Ag deposit, Inner Mongolia, NE China: constraints from geochemistry, fluid inclusion, zircon geochronology and stable isotopes[J]. Ore Geology Reviews, 2020, 122. DOI: 10.1016/j.oregeorev.2020.103528 DOI
[31]	YUAN M W, LI S R, LI C L, et al. Geochemical and isotopic composition of auriferous pyrite from the Yongxin gold deposit, Central Asian Orogenic Belt: implication for ore genesis[J]. Ore Geology Reviews, 2018, 93:255-267. DOI URL
[32]	WAN L, LU C, ZENG Z, et al. Nature and significance of the late Mesozoic granitoids in the southern Great Xing’an range, eastern Central Asian Orogenic Belt[J]. International Geology Review, 2019, 61(5):584-606. DOI URL
[33]	邵济安, 王友, 唐克东. 有关内蒙古西拉木伦带古生代—早中生代构造环境的讨论[J]. 岩石学报, 2017, 33(10):3002-3010.
[34]	SAFONOVA I. Juvenile versus recycled crust in the Central Asian Orogenic Belt: implications from ocean plate stratigraphy, blueschist belts and intra-oceanic arcs[J]. Gondwana Research, 2017, 47:6-27. DOI URL
[35]	LI S Z, ZANG Y B, WANG P C, et al. Mesozoic tectonic transition in South China and initiation of Palaeo-Pacific subduction[J]. Earth Science Frontiers, 2017, 24(4):213-225.
[36]	WILDE S A. Final amalgamation of the Central Asian Orogenic Belt in NE China: Paleo-Asian Ocean closure versus Paleo-Pacific plate subduction: a review of the evidence[J]. Tectonophysics, 2015, 662:345-362. DOI URL
[37]	姚书振, 周宗桂, 宫勇军, 等. 初论成矿系统的时空结构及其构造控制[J]. 地质通报, 2011, 31(4):469-477.
[38]	邵济安, 牟保磊, 朱慧忠, 等. 大兴安岭中南段中生代成矿物质的深部来源与背景[J]. 岩石学报, 2010, 26(3):649-656.
[39]	ZHAI D, WILLIAMS-JONES A E, LIU J, et al. The genesis of the giant Shuangjianzishan epithermal Ag-Pb-Zn deposit, Inner Mongolia, Northeastern China[J]. Economic Geology, 2020, 115(1):101-128. DOI URL
[40]	ZHANG H, ZHAI D, LIU J, et al. Fluid inclusion and stable (HOC) isotope studies of the giant Shuangjianzishan epithermal Ag-Pb-Zn deposit, Inner Mongolia, NE China[J]. Ore Geology Reviews, 2019, 115. DOI: 10.1016/j.oregeorev.2019.103170 DOI
[41]	ZHAI D, LIU J, COOK N J, et al. Mineralogical, textural, sulfur and lead isotope constraints on the origin of Ag-Pb-Zn mineralization at Bianjiadayuan, Inner Mongolia, NE China[J]. Mineralium Deposita, 2019, 54(1):47-66. DOI URL
[42]	ZHAI D, LIU J, ZHANG A, et al. U-Pb, Re-Os, and ⁴⁰Ar/³⁹Ar geochronology of porphyry Sn±Cu±Mo and polymetallic (Ag-Pb-Zn-Cu) vein mineralization at Bianjiadayuan, inner Mongolia, northeast China: implications for discrete mineralization events[J]. Economic Geology, 2017, 112(8):2041-2059. DOI URL
[43]	ZHAI D, LIU J, ZHANG H, et al. S-Pb isotopic geochemistry, U-Pb and Re-Os geochronology of the Huanggangliang Fe-Sn deposit, Inner Mongolia, NE China[J]. Ore Geology Reviews, 2014, 59:109-122. DOI URL
[44]	ZHAI D, LIU J, WANG J, et al. Zircon U-Pb and molybdenite Re-Os geochronology, and whole-rock geochemistry of the Hashitu molybdenum deposit and host granitoids, Inner Mongolia, NE China[J]. Journal of Asian Earth Sciences, 2014, 79:144-160. DOI URL
[45]	邵济安, 张履桥, 牟保磊. 大兴安岭中生代伸展造山过程中的岩浆作用[J]. 地学前缘, 1999, 6(4):339-346.
[46]	牛树银, 陈超, 张福祥, 等. 大兴安岭中南段成矿控矿构造分析[J]. 地质论评, 2016, 62(B11):323-324.
[47]	冯志强. 大兴安岭北段古生代构造-岩浆演化[D]. 长春: 吉林大学, 2015.
[48]	XIAO R. Geological and tectonic evolution characteristics of polymetallic metallogenic belt[J]. Arabian Journal of Geosciences, 2020, 13(18):1-12. DOI URL
[49]	方乙, 张寿庭, 邹灏, 等. 浅覆盖区萤石矿综合勘查方法研究: 以内蒙古林西赛波萝沟门萤石矿为例[J]. 成都理工大学学报(自然科学版), 2014, 41(1):94-101.
[50]	EZE C L, MAMAH L I, ISRAEL-COOKEY C. Very low frequency electromagnetic (VLF-EM) response from a lead sulphide lode in the Abakaliki lead/zinc field, Nigeria[J]. International Journal of Applied Earth Observation and Geoinformation, 2004, 5(2):159-163. DOI URL
[51]	陈伟军, 郝情情, 褚少雄, 等. 甚低频电磁法在隐伏金属矿床定位预测中的应用: 以大兴安岭西南段铜多金属矿点为例[J]. 地质与勘探, 2017, 53(3):528-532.
[52]	方乙, 邹灏, 王光凯, 等. 浅覆盖区萤石矿综合勘查方法研究: 以内蒙古林西赛波萝沟门萤石矿为例[J]. 桂林理工大学学报, 2013, 33(2):246-251.
[53]	PIOREK S. Field-portable X-ray fluorescence spectrometry: past, present, and future[J]. Field Analytical Chemistry & Technology, 1997, 1(6):317-329.
[54]	王振亮, 张寿庭, 梁晓辉, 等. X荧光仪及视电阻率测量的综合找矿方法应用: 以内蒙古碧流台银铅锌多金属矿为例[J]. 矿产勘查, 2012, 3(6):811-817.
[55]	李欣宇, 邹灏, 张强, 等. 便携式X荧光元素分析法在浅覆盖区萤石矿勘查中的应用与分析: 以内蒙古乌力吉敖包萤石矿为例[J]. 物探化探计算技术, 2018, 40(5):681-688.
[56]	高乐, 周永章, 王琨, 等. 偏最小二乘降维法在粤西层控型铅锌矿床发育区水系沉积物地球化学测量数据分析中的应用[J]. 大地构造与成矿学, 2020, 44(2):258-266.
[57]	张寿庭. 浙江武义盆地中段萤石矿体垂向分带特征与规律[J]. 西南工学院学报, 1997, 12(4):52-59.
[58]	徐旃章, 张寿庭. 浙江省萤石矿时空演化序列与典型萤石矿田的剖析及评价[M]. 北京: 地质出版社, 2013.
[59]	张作伦, 曾庆栋, 叶杰, 等. 甚低频电磁法在矿体勘查中的应用[J]. 地质与勘探, 2008, 44(1):67-69.
[60]	FRASER D C. Contouring of VLF-EM data[J]. Geophysics, 1969, 34(6):958-967. DOI URL