Whole-rock and mineral chemical data from a profile of the ~900 Ma Niutishan Fe-Ti-rich sill in XuZhou, North China

In this article, the geochemical data of a ~900 Ma mafic sill from Xuzhou, North China are reported. These datasets include 37 whole-rock major and trace element data, and 21 major element data on plagioclase, 20 major element data on clinopyroxene crystals, 10 major element data on apatite crystals, 7 major element data of preserved coexisting titano-magnetite and ilmenite grains, 36 major element data on different types of ilmenite crystals, 13 major element and 11 trace element data on titanite. These data are associated with Su et al. “Petrogenesis of a ~900 Ma mafic sill from Xuzhou, North China: Implications for the genesis of Fe-Ti-rich rocks” (Su et al., 2018), and in which their characters and variations were interpreted and discussed.


Subject area
Geology More specific subject area Petrology Type of data Table  How data  The erosion surface of sample was carefully removed and fresh samples were made for sample powders and thin sections Experimental features For major elements, sample powders, $ 0.5 g for each, were fused into a glass bead with $ 5.0 g of lithium tetraborate; whole-rock trace element analyses were determined using an ELEMENT instrument after HNO 3 þ HF digestion of approximately 40 mg of sample powder in a Teflon vessel; thin and polished sections of the samples that were coated with carbon were made for the analysis of major elements on different minerals.

Value of the data
The whole-rock and mineral chemical data from a specific profile of the Niutishan mafic sill, one of the $ 900 Ma sills from Xuzhou, North China were firstly reported.
The datasets give basic information for a representative Fe-Ti-rich component-bearing mafic sill, and can be used for further investigation.
This Fe-Ti-rich sill is characterized by the presence of 45 vol% of titanite, and thus compositions of this mineral are of broad interesting for the related community.

Data
In this paper, we report whole-rock and minerals geochemical data from a specific profile of a $900 Ma mafic sill in XuZhou, North China. These datasets include 37 whole-rock major and trace element data (Table S1), and 21 major element data on plagioclase (Table 1), 20 major element data on clinopyroxene crystals (Table 2), 10 major element data on apatite crystals (Table 3), 7 major element data of preserved coexisting titano-magnetite and ilmenite grains (Table 4), 36 major element data on different types of ilmenite crystals (Table 5), 13 major element (Table 6) and 11 trace element data on titanite (Table 7). These data are associated with Su et al. "Petrogenesis of a $ 900 Ma mafic sill from Xuzhou, North China: Implications for the genesis of Fe-Ti-rich rocks" [1]. The variation of the listed data (both of the whole-rock and minerals chemical compositions) from the specific profile of the sill are significant. The highest values for MgO, Cr and the most primitive plagioclase composition occur in LZa (-19.4 to -21.8 m), the highest values for FeO t and TiO 2 occur in LZb (-17.7 to -18.7 m), the highest value for P 2 O 5 occurs in LZc (-16.7 to -17.7 m), and the most enriched incompatible elements occur in the MZ (-3.6 to -16.7). The uppermost rocks show the near mirror image of the lower section [1].

Sampling
A total of 38 samples were collected systematically with a constant spacing of $ 0.5 m from the top to the bottom of the Niutishan mafic sill. The true stratigraphic position and the distance between samples were corrected based on the average local dip (17°SE). The real outcrop thickness of this sill is $22 m, and the top surface was set to '0 m'. The erosion surface of sample was carefully removed. All analytical procedures were accomplished at the Institute of Geology and Geophysics, Chinese Academy of Sciences (IGGCAS).

Whole-rock analysis
Sample powders, $ 0.5 g for each, were fused into a glass bead with $ 5.0 g of lithium tetraborate. Major elements were measured using a PANalytical AXIOS Minerals instrument, and ferrous iron was measured by titration [2] (Table S1). The uncertainties for major elements wereo1.0 wt%. The precision was better than 0.2 wt% in the analytical range. The loss-on-ignition (LOI) was determined by the weight loss for a powdered sample after 2 h heating at 1000°C and 30 min cooling to ambient temperature. Two reference materials GSR1 and GSR3 were measured to evaluate the chemical preparation procedure and the condition of the instrument. GSR1 and GSR3 data are listed in Table S1, and are consistent with the reference values. Whole-rock trace element analyses were determined using an ELEMENT instrument after HNO 3 þ HF digestion of approximately 40 mg of sample powder in a Teflon vessel, with accuracy and reproducibility monitored using Chinese national standard samples GSR1 and GSR3. GSR1 and GSR3 data are listed in Table S1 and are consistent with the reference values. Both precision and accuracy are better than 5% for most of the trace elements (Table S1).

Electron microprobe mapping and analysis
Thin and polished sections of the gabbroic rocks that were coated with carbon were made for the analysis of major elements and backscattered electron images. Major element compositions of plagioclase, clinopyroxene, apatite and ilmenite were obtained by a JEOL JXA 8100 instrument (an electron microprobe analysis). Quantitative analyses were performed using wavelengthdispersive spectrometers (WDS) with an acceleration voltage of 15 kV, a beam current of 20 nA, and a defocused beam size of 5 μm. Major element compositions of titanite, titano-magnetite and ilmenite lamellae were measured by CAMECA SX Five FE instrument (an electron probe micro-analyser). Quantitative analyses were performed using wavelength-dispersive spectrometers (WDS) with an acceleration voltage of 15 kV, a beam current of 30 nA, and a focused beam size (0 μm). The peak counting time was 10-20 s for all elements, and the background counting time was 10 s on the highand low-energy background positions. All data were corrected online using a modified ZAF (atomic number, absorption, fluorescence) correction procedure. The detection limits were in the range of 0.008-0.02 wt% (1σ). The accuracy was generally less than 1 wt% for oxide contents greater than 5 wt% (Table 1-6).

Fe-Ti two-oxide geothermometer and oxygen barometer
There are a few preserved coexisting titano-magnetite and ilmenite grains in the thin sections, due to the exsolved mature of ilmenite in oxide pairs. The titano-magnetite and nearly coeval thick ilmenite lamellae led to our adoption of a revised Fe-Ti two-oxide geothermometer and oxygen barometer. Temperature and oxygen fugacity were calculated using the online MELTS software (http://melts.ofm-research.org).