Application of big data in bauxite provenance: A case study of Yanlong area in Western Henan, China

The application of big data is of great significance to the quantitative study on provenance. In this paper, taking the bauxite in Yanlong area, western Henan, as an example, the detrital zircon U-Pb age big data obtained by Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICP-MS) are used to study the bauxite provenance. The results show that the Caledonian and Sibao Jinning zircons are from the North Qinling Orogenic Belt (NQOB). In contrast, the Lvliang and Wutai zircons may be derived from karst insoluble of Majiagou Formation limestone.


Introduction
Big data was first proposed by McKinsey, a world-famous consulting company, in the research report in the 1980s. In the research report, big data is defined as the acquisition, processing and analysis of data through network technology, from which massive valuable data are extracted [1]. Big data has been widely used in various fields due to its advantages, such as fast processing efficiency, high storage security, and high analysis accuracy [2].
There are also controversies about the source of the bauxite in the southeast of the North China Block, which is based on indirect evidence such as the spatial location of the bauxite. With the indepth development of computer technology and internet applications, wide variety of sources, fast operation, and massive amounts of information form big data, which gives birth to a new era of technology [3], so a new working model for solutions geological problems (such as provenance) comes into being.

Big data provenance
Zircon is widely distributed in all kinds of rocks, rich in U, Th and low in Pb, with high sealing temperature and stable minerals. It can provide accurate U-Pb age and is an ideal object for U-Pb dating [4][5][6][7][8]. At present, there are several methods for single-grain zircon analysis. SIMS (secondary ion mass spectrometry): in-situ analysis, expensive. SHRIMP: in-situ, high precision, sample damage is small, expensive, and long time to test. LA-ICP-MS: in-situ, fast, economical, large analysis volume, less accurate (meet the source requirements of a large amount of data).
LA-ICP-MS has been successfully used in the study of single-particle zircon, which has promoted provenance analysis and has become a method for U-Pb isotopic dating [9,10]. Based on zircon U-Pb dating, in-situ isotope Lu-Hf, combined with constraints of genetic mineralogy and geochemistry, LA-ICP-MS has become an effective method for studying material sources [4][5][6][7][8]11,12].

Application examples
LA-ICP-MS was performed on two representative lithologies of pisolitic-oolitic (clastic) bauxite (sample ZK0008-43) and bauxite mudstone (sample ZK0008-44) in Benxi Formation in borehole ZK0008 in Yanlong area (figure 1) detrital zircon U-Pb age determination, two samples were tested in a total of two hundred zircons, each sample obtained Th, U, Pb, Th/U and other components, 207 Pb/ 206 Pb、 206 Pb/ 238 U、 207 Pb/ 235 U isotopic ratios were obtained for each sample, 207 Pb/ 206 Pb、 206 Pb/ 238 U、 207 Pb/ 235 U ages, i.e. detrital zircon U-Pb age three thousand and two hundred data [8]. The Hf isotopic data of twenty-six detrital zircons from the pisolitic-oolitic (clastic) bauxite (sample ZK0008-43) of the Benxi Formation were measured. 176 Yb/ 177 Hf、 176 Hf/ 177 Hf、 176 Lu /177 Hf、2σ、ε hf (t)、two stage model age (T DM2 )、f(Lu/Hf) data, that is, HF isotopes need to analyse two hundred and thirty-four data [8]. a-Tectonic unit sketch of the study area (modified from [20]), b-Geologic column and sampling positions (modified from [8]). LA-ICP-MS detrital zircon U-Pb dating results remove thirteen zircons whose concordance degree is less than 90% and do not participate in the age spectrum statistics. One hundred and eighty-seven 3 detrital zircons with concordance degree than 90% are divided into two groups: the first group contains one hundred and thirty-six zircons, whose ages range from 378 Ma to 544 Ma, accounting for 73%, with a peak value of 443 Ma (figure 2); The second group of fifty-one zircons, ranging from 629 Ma to 3116 Ma, is from Precambrian, accounting for 27%, with three age peaks: 992 Ma (accounting for 45% of the Precambrian zircons), 1817 Ma (accounting for 14% of the Precambrian zircons) and 2500 Ma (accounting for 10% of the Precambrian zircons) (Figure 2), respectively, corresponding to the age of Sibao-Jinning, Lvliang and Wutai periods. According to the morphology, trace and REE characteristics of detrital zircons, the Caledonian and Sibao Jinning zircons are magmatic zircons. In contrast, the Lvliang and Wutai zircons are mainly metamorphic accretionary zircons of magmatic zircons.
According to the comparison of the age composition of detrital zircon with the U-Pb age spectrum of the NQOB, Majiagou Formation limestone, and North China Craton basement, combined with the tectonic background of the study area, zircon genetic mineralogy and Hf isotope analysis, it is believed that the Caledonian zircons and the Sibao-Jinning zircons derived from the NQOB. In contrast, the Lvliang and Wutai zircons may be derived from karst insoluble of Majiagou Formation limestone.

Conclusion
The detrital zircon age data of bauxite provenance obtained by LA-ICP-MS. Detrital zircon U-Pb ages are divided into two groups: the first group ages range from 378 Ma to 544 Ma, accounting for 73%, with a peak about 443 Ma; the second group ranging from 629 Ma to 3116 Ma, is from Precambrian, with three age peaks, corresponding to the age of Sibao-Jinning, Lvliang and Wutai periods.
It is proved that big data of LA-ICP-MS detrital zircon U-Pb dating and Hf isotope can quantitatively solve the problem of bauxite provenance. The Caledonian zircons and the Sibao-Jinning zircons derived from the North Qinling Orogenic Belt, while the Lvliang and Wutai zircons may be derived from karst insoluble of Majiagou Formation limestone.