Magnetite geochemical big data: Dataset construction and application in genetic classification of ore deposits

doi:10.13745/j.esf.sf.2021.1.10

Abstract

Abstract:

Magnetite is an oxide mineral commonly found in magmatic, hydrothermal and sedimentary deposits. Its geochemical elemental composition is largely dependent on temperature, oxygen fugacity and other physicochemical conditions, and can reveal the ore-forming environment and indicate the genetic type of ore deposits. The major and trace elements in magnetite have been used for genetic classification of ore deposits since the 1960s. However, due to genetic diversity of ore deposits and complexity of geochemical composition of magnetite from the same type of ore deposits, the applicability of magnetite discrimination diagrams is often limited based on limited magnetite geochemical data. In this study, we collected from various publications a large amount of magnetite geochemical data (n=7388) determined by electron probe microanalysis (EPMA) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) to construct, preliminarily, two magnetite geochemical big data sets, and subsequently established a new genetic classification model based on random forest algorithm, and explored the importance of trace elements in the genetic classification of ore deposits. The results show that magnetite big data mining based on a machine learning algorithm can effectively distinguish the main types of ore deposit, with an overall classification accuracy up to 95%. Because the LA-ICP-MS magnetite data set contains high quality data on many trace elements, the classification accuracy is higher based on LA-ICP-MS data than on EPMA data, indicating the classification accuracy of ore deposit is affected by the number of trace elements in magnetite and by the accuracy of data analysis. At the same time, we found element V plays an important role in the classification of ore deposits. In addition, analyzing new magnetite data using the new discrimination model can yield the probability of each ore type and effectively distinguish the genetic type of ore deposit.

Key words: magnetite, geochemical big data, random forest, genetic type of ore deposit

CLC Number:

HONG Shuang, ZUO Renguang, HU Hao, XIONG Yihui, WANG Ziye. Magnetite geochemical big data: Dataset construction and application in genetic classification of ore deposits[J]. Earth Science Frontiers, 2021, 28(3): 87-96.

Figures/Tables 11

Table 1 Number of published magnetite EMPA and LA-ICP-MS data records for different types of mineral deposits

矿床类型	数据集数量/条
矿床类型	EPMA	LA-ICP-MS
IOCG	680	490
斑岩型	535	1 488
夕卡岩型	511	813
VMS	432	11
IOA	628	465
BIF	61	628
Fe-Ti	66	332
Ni-Cu	198	0

Fig.1 World map showing the locations of the selected ore deposits

Fig.2 Boxplot of EPMA (a) and LA-ICP-MS (b) result for trace elements in magnetite from different types of ore deposits

Fig.3 Classification accuracy (a) and element importance (b) based on EPMA data in Experiment 1

Fig.4 Classification accuracy (a) and element importance (b) based on LA-ICP-MS data in Experiment 1

Fig.5 Classification accuracy (a) and element importance (b) based on EPMA data in Experiment 2

Fig.6 Classification accuracy (a) and element importance (b) based on LA-ICP-MS data in Experiment 2

Fig.7 Classification accuracy (a) and element importance (b) based on EPMA data in Experiment 3

Fig.8 Classification accuracy (a) and element importance (b) based on LA-ICP-MS data in Experiment 3

Table 2 Classification results based on EPMA data (data from [39])

样本编号	各类型矿床的概率
样本编号	BIF	IOA	热液型	岩浆型
1	0.00	0.43	0.57	0.00
2	0.00	0.58	0.39	0.04
3	0.00	0.69	0.26	0.05
4	0.00	0.55	0.40	0.05
5	0.00	0.36	0.59	0.05
6	0.00	0.37	0.58	0.05
7	0.00	0.82	0.18	0.00
8	0.00	0.73	0.26	0.00
9	0.00	0.42	0.49	0.09
10	0.00	0.52	0.46	0.02
平均概率	0.00	0.55	0.41	0.04

Table 3 Classification results based on LA-ICP-MS data (data from [40])

样本编号	各类型矿床的概率
样本编号	BIF	IOA	热液型	岩浆型
1	0.07	0.69	0.22	0.02
2	0.08	0.69	0.21	0.02
3	0.08	0.69	0.20	0.02
4	0.11	0.59	0.28	0.02
5	0.10	0.58	0.30	0.02
6	0.13	0.56	0.29	0.02
7	0.14	0.57	0.29	0.00
8	0.00	0.44	0.47	0.09
9	0.13	0.56	0.29	0.02
10	0.10	0.58	0.30	0.02
平均概率	0.10	0.57	0.30	0.03

References 48

[1]	WARK D A, WATSON E B. TitaniQ: a titanium-in-quartz geothermometer[J]. Contributions to Mineralogy and Petrology, 2006, 152(6):743-754. DOI URL
[2]	KEITH M, HAASE K M, SCHWARZ-SCHAMPERA U, et al. Effects of temperature, sulfur, and oxygen fugacity on the composition of sphalerite from submarine hydrothermal vents[J]. Geology, 2014, 42(8):699-702. DOI URL
[3]	REICH M, DEDITIUS A, CHRYSSOULIS S, et al. Pyrite as a record of hydrothermal fluid evolution in a porphyry copper system: a SIMS/EMPA trace element study[J]. Geochimica et Cosmochimica Acta, 2013, 104:42-62. DOI URL
[4]	金露英, 秦克章, 李光明, 等. 大兴安岭北段岔路口斑岩 Mo-热液脉状Zn-Pb成矿系统硫化物微量元素的分布、起源及其勘探指示[J]. 岩石学报, 2015, 31(8):2417-2434.
[5]	DUPUIS C, BEAUDOIN G. Discriminant diagrams for iron oxide trace element fingerprinting of mineral deposit types[J]. Mineralium Deposita, 2011, 46(4):319-335. DOI URL
[6]	HUANG X W, QI L, MENG Y M. Trace element geochemistry of magnetite from the Fe(-Cu) deposits in the Hami region, Eastern Tianshan Orogenic Belt, NW China[J]. Acta Geologica Sinica-English Edition, 2014, 88(1):176-195.
[7]	NIELSEN R L, FORSYTHE L M, GALLAHAN W E, et al. Major-and trace-element magnetite-melt equilibria[J]. Chemical Geology, 1994, 117(1/2/3/4):167-191. DOI URL
[8]	DEYELL C L, HEDENQUIST J W. Trace element geochemistry of enargite in the Mankayan district, Philippines[J]. Economic Geology, 2011, 106(8):1465-1478. DOI URL
[9]	NADOLL P, ANGERER T, MAUK J L, et al. The chemistry of hydrothermal magnetite: a review[J]. Ore Geology Reviews, 2014, 61:1-32. DOI URL
[10]	GHIORSO M S, SACK R O. Thermochemistry of the oxide minerals[J]. Reviews in Mineralogy and Geochemistry, 1991, 25(1):221-264.
[11]	ANDERSON J L, BARTH A P, WOODEN J L, et al. Thermometers and thermobarometers in granitic systems[J]. Reviews in Mineralogy and Geochemistry, 2008, 69(1):121-142. DOI URL
[12]	BUDDINGTON A F, LINDSLEY D H. Iron-titanium oxide minerals and synthetic equivalents[J]. Journal of Petrology, 1964, 5(2):310-357. DOI URL
[13]	SCHEKA S A, PLATKOV A V, VEZHOSEK A A, et al. The trace element paragenesis of magnetite[M]. Moscow: Nauka, 1980: 147(in Russian).
[14]	RAMDOHR P. The ore minerals and their intergrowths[M]. New York: Pergamon Press, 1980.
[15]	LEACH D L, BRADLEY D C, HUSTON D, et al. Sediment-hosted lead-zinc deposits in Earth history[J]. Economic Geology, 2010, 105(3):593-625. DOI URL
[16]	MALMQVIST D, PARASNIS D S. Aitik: geophysical documentation of a third-generation copper deposit in north Sweden[J]. Geoexploration, 1972, 10(3):149-200. DOI URL
[17]	MCENROE S A, ROBINSON P, PANISH P T. Aeromagnetic anomalies, magnetic petrology, and rock magnetism of hemo-ilmenite-and magnetite-rich cumulate rocks from the Sokndal Region, South Rogaland, Norway[J]. American Mineralogist, 2001, 86(11/12):1447-1468. DOI URL
[18]	GREGORY D D, CRACKNELL M J, LARGE R R, et al. Distinguishing ore deposit type and barren sedimentary pyrite using laser ablation-inductively coupled plasma-mass spectrometry trace element data and statistical analysis of large data sets[J]. Economic Geology, 2019, 114(4):771-786. DOI URL
[19]	NADOLL P, KOENIG A E. LA-ICP-MS of magnetite: methods and reference materials[J]. Journal of Analytical Atomic Spectrometry, 2011, 26(9):1872-1877. DOI URL
[20]	SAVARD D, BARNES S J, DARE S A S, et al. Improved calibration technique for magnetite analysis by LA-ICP-MS[J]. Mineralogical Magazine, 2012, 76(6):2329.
[21]	MÜLLER B, AXELSSON M D, ÖHLANDER B. Trace elements in magnetite from Kiruna, northern Sweden, as determined by LA-ICP-MS[J]. Gff, 2003, 125(1):1-5. DOI URL
[22]	BEAUDOIN G, DUPUIS C. Iron-oxide trace element fingerprinting of mineral deposit types. Exploring for iron oxide copper-gold deposits: Canada and global analogues[R]. In Exploring for iron oxide copper-gold deposits: Canada and global analogues. GAC Short Course Notes, 2009: 107-121.
[23]	黄柯, 朱明田, 张连昌, 等. 磁铁矿LA-ICP-MS分析在矿床成因研究中的应用[J]. 地球科学进展, 2017, 32(3):262-275.
[24]	徐国风, 邵洁涟. 磁铁矿的标型特征及其实际意义[J]. 地质与勘探, 1979, 3:30-37.
[25]	林师整. 磁铁矿矿物化学、成因及演化的探讨[J]. 矿物学报, 1982, 3:166-174.
[26]	陈光远, 孙岱生, 殷辉安. 成因矿物学与找矿矿物学[M]. 重庆: 重庆出版社, 1987.
[27]	王顺金. 论磁铁矿的标型特征[M]. 武汉: 中国地质大学出版社, 1987.
[28]	LOBERG B E H, HORNDAHL A K. Ferride geochemistry of Swedish Precambrian iron ores[J]. Mineralium Deposita, 1983, 18(3):487-504. DOI URL
[29]	SINGOYI B, DANYUSHEVSKY L, DAVIDSON G J, et al. Determination of trace elements in magnetites from hydrothermal deposits using the LA-ICP-MS technique[C]// Keystone: 2006 Conference on Society of Economic Geologists, USA. 2006: 367-368.
[30]	陈华勇, 韩金生. 磁铁矿单矿物研究现状、存在问题和研究方向[J]. 矿物岩石地球化学通报, 2015, 34(4):724-730.
[31]	DARE S A S, BARNES S J, BEAUDOIN G, et al. Trace elements in magnetite as petrogenetic indicators[J]. Mineralium Deposita, 2014, 49(7):785-796. DOI URL
[32]	BOUTROY E, DARE S A A, BEAUDOIN G, et al. Magnetite composition in Ni-Cu-PGE deposits worldwide: application to mineral exploration[J]. Journal of Geochemical Exploration, 2014, 145:64-81. DOI URL
[33]	KNIPPING J L, BILENKER L D, SIMON A C, et al. Trace elements in magnetite from massive iron oxide-apatite deposits indicate a combined formation by igneous and magmatic-hydrothermal processes[J]. Geochimica et Cosmochimica Acta, 2015, 171:15-38. DOI URL
[34]	PISIAK L K, CANIL D, LACOURSE T, et al. Magnetite as an indicator mineral in the exploration of porphyry deposits: a case study in till near the Mount Polley Cu-Au deposit, British Columbia, Canada[J]. Economic Geology, 2017, 112(4):919-940. DOI URL
[35]	HUANG X W, BOUTROY é, MAKVANDI S, et al. Trace element composition of iron oxides from IOCG and IOA deposits: relationship to hydrothermal alteration and deposit subtypes[J]. Mineralium Deposita, 2019, 54(4):525-552. DOI URL
[36]	BREIMAN L. Random forests[J]. Machine learning, 2001, 45(1):5-32. DOI URL
[37]	BREIMAN L, CUTLER A. RFtools: for predicting and understanding data[C]. Interface'04 Workshop, 2004. http://oz.berkeley.edu/users/breiman/Random Forests.
[38]	COHEN J. A coefficient of agreement for nominal scales[J]. Educational and Psychological Measurement, 1960, 20(1):37-46. DOI URL
[39]	OVALLE J T, LA CRUZ N L, REICH M, et al. Formation of massive iron deposits linked to explosive volcanic eruptions[J]. Scientific reports, 2018, 8(1):1-11.
[40]	LA CRUZ N L, OVALLE J T, SIMON A C, et al. The geochemistry of magnetite and apatite from the El Laco iron oxide-apatite deposit, Chile: implications for ore genesis[J]. Economic Geology, 2020, 115(7):1461-1491. DOI URL
[41]	BROUGHM S G, HANCHAR J M, TORNOS F, et al. Mineral chemistry of magnetite from magnetite-apatite mineralization and their host rocks: examples from Kiruna, Sweden, and El Laco, Chile[J]. Mineralium Deposita, 2017, 52(8):1223-1244. DOI URL
[42]	NYSTROEM J O, HENRIQUEZ F. Magmatic features of iron ores of the Kiruna type in Chile and Sweden: ore textures and magnetite geochemistry[J]. Economic geology, 1994, 89(4):820-839. DOI URL
[43]	NASLUND H R, HENRIQUEZ F, NYSTRÖM J O, et al. Magmatic iron ores and associated mineralisation: examples from the Chilean high Andes and coastal Cordillera[M]. Adelaide: hydrothermal iron oxide copper-gold & related deposits: a global perspective, PGC Publishing, 2002, 2:207-226.
[44]	VELASCO F, TORNOS F, HANCHAR J M. Immiscible iron- and silica-rich melts and magnetite geochemistry at the El Laco volcano (northern Chile): evidence for a magmatic origin for the magnetite deposits[J]. Ore Geology Reviews, 2016, 79:346-366. DOI URL
[45]	HITZMAN M W, ORESKES N, EINAUDI M T. Geological characteristics and tectonic setting of Proterozoic iron oxide (Cu±U±Au±REE) deposits[J]. Precambrian Research, 1992, 58:241-287. DOI URL
[46]	RHODES A L, ORESKES N, SHEETS S. Geology and rare earth element geochemistry of magnetite deposits at El Laco, Chile[J]. Society of Economic Geologists Special Publication, 1999, 7:299-332.
[47]	SILLITOE R H, BURROWS D R. New field evidence bearing on the origin of the El Laco magnetite deposit, northern Chile[J]. Economic Geology, 2002, 97(5):1101-1109.
[48]	HU H, LI J W, HARLOV D E, et al. A genetic link between iron oxide-apatite and iron skarn mineralization in the Jinniu volcanic basin, Daye district, eastern China: evidence from magnetite geochemistry and multi-mineral U-Pb geochronology[J]. Geological Society of America Bulletin, 2020, 132(5/6):899-917. DOI URL