Supplementary Information s46

SUPPLEMENTARY INFORMATION

Isotopic evidence for continental ice sheet in mid-latitude region in the supergreenhouse Early Cretaceous

Wu-Bin Yang1, He-Cai Niu1 †, Wei-Dong Sun1,2 †, Qiang Shan1, Yong-Fei Zheng3,

Ning-Bo Li1,4, Cong-Yin Li2, Nicholas T. Arndt5, Xing Xu6, Yu-Hang Jiang1,4, Xue-Yuan Yu1

1 CAS Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

2 State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China

3 CAS Key Laboratory of Crust-Mantle Materials and Environments, School of Earth and Space Sciences, University of Science and Technology of China, Hefei 230026, China

4 University of Chinese Academy of Sciences, Beijing 100049, China

5 ISTerre, Université de Grenoble, St Martin d’Heres 38401, France

6 Key Laboratory of Evolutionary Systematics of Vertebrates, Institute of Vertebrate Paleontology and Paleoanthropology, Chinese Academy of Sciences, Beijing 100044, China

†Corresponding authors: H.C.N. () and W.D.S. ()

First author: W.B.Y. ()

Supplementary Figures

Figure S1 Discrimination diagrams show the Baerzhe granites are A-type of granite, modified after Whalen et al1. Open squares show barren granite and the solid squares show mineralized granite. Data are taken from Yang et al.2.

Figure S2 REE distribution patterns and Cl images of hydrothermal and magmatic zircons from the Baerzhe A-type granites (authors’ unpublished data, show in Table S1). Hydrothermal zircon crystals occure in mineralizaed granite are tetragonal dipyramids, murky and featureless, and LREE-rich. Magmatic zircon crystals from the barren granite occur as prisms and oscillatory-zoned.

Figure S3 δ18O values of the two zircon standards analyses of this study. Ten analyses of zircon 91500 yield a mean δ18O value of 10.15±0.13 (2σ), and 44 analyses of Penglai zircon megacrysts yield a mean value of 5.20±0.05 (2σ).

Figure S4 The 176Hf/177Hf values of the three zircon standards analysed in this study are in good agreement with the reported values of Yuan et al3, with the following mean values: zircon 91500 = 0.282307±0.000004 (2σ), Monastery = 0.282739±0.000002 (2σ) and zircon GJ-1 = 0.282015±0.000003 (2σ).

Figure S5 Whole rock Hf-Nd isotope data for the Baerzhe granites, showing the parental magma has juvenile components. The fields for mid-ocean ridge basalts (MORB), ocean island basalts (OIB), and basalts from Reykjanes ridge, Iceland and Azores were all referred from Nowell et al4. The spots from authors’ unpublished data, 2σ internal errors of individual data points are smaller than the symbol size.

Figure S6 δ18O values determined by in-situ analysis of hydrothermal and magmatic zircons, as well as bulk rock and minerals. VSMOW is Vienna Standard Mean Ocean Water. Normal mantle zircon has a δ18O value of 5.3 ± 0.3‰5. The δ18O values of bulk rock, quartz phenocrysts, K-feldspar and bulk zircon are from Yuan et al6. Note that three SIMS analyses of magmatic zircon have mixed signals.

Figure S7 δ18O values of quartz and K-feldspar from the Baerzhe granite show remarkable oxygen isotopic disequilibrium. Isotherms are calculated after Zheng7 using data from Yuan et al6 (Table S3).

Figure S8 Variation of O isotope fractionation between quartz and magmatic zircon (ΔQuartz–zircon) with equilibrium temperature (°C), from theoretical calculations of Zheng7. The mean value of ΔQuartz–zircon =1.90±0.55‰ was calculated from the weighted average magmatic zircon δ18O value (excluding three mixed spots) of 3.47±0.11‰ (1σ) and the average quartz δ18O value of 5.37±0.54‰ (1σ), at an equilibrium temperature of ca.1030 °C.

Supplementary Tables

Table S1 Laser ablation ICP-MS analyses (ppm) of magmatic and hydrothermal zircons from the Baerzhe A-type granite (authors’ unpublished data).

Table S2 SIMS U-Pb analytical results of the hydrothermal and magmatic zircons from Baerzhe A-type granite.

Notes: a the value of 206Pb/204Pbm is the measured value.

b f206(%) is the percentage of common 206Pb in total 206Pb.

Table S3 SIMS oxygen isotopes analytical results of the hydrothermal and magmatic zircons, and the corresponding δ18O values of hydrothermal fluid and mean annual temperatures.