The South China Craton (SCC)

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Table of contents

1 Introduction
1.1 The continental lower crust
1.1.1 Water in the deep crust
1.1.2 Water in nominally anhydrous minerals
1.1.3 H-O-Li stable isotopes
1.2 Framework of this study
1.3 Aim of this study
1.4 Structure of this study
2 Geological background
2.1 The North China Craton
2.2 The Dabie-Sulu UHP Belt
2.3 The South China Craton
2.4 Lithospheric thinning in eastern China
3 Localities and samples
3.1 Hannuoba
3.2 Nushan
3.3 Daoxian
3.4 Samples
3.4.1. Hannuoba xenolith granulites
3.4.2. Hannuoba terrain granulites
3.4.3. Nushan xenolith granulites
3.4.4. Daoxian xenolith granulites
3.4.5. Hannuoba xenolith peridotites
3.4.6. Nushan xenolith peridotites
4 Analytical methods
4.1 Petrography and sample documentation
4.2 Electron microprobe (EMP)
4.3 Fourier transform infrared spectroscopy (FTIR)
4.3.1 Spectrometer and measurement parameters
4.3.2 Calculation of water content
4.4 Isotopic ratio mass spectrometry (IRMS)
4.5 Secondary ion mass spectrometry (SIMS)
4.5.1 Rare earth elements
4.5.2 Hydrogen isotopes
4.5.3 Oxygen isotopes
4.5.4 Lithium contents and isotopic compositions
5 Results
5.1 EMP results
5.1.1 Granulites
5.1.2 Peridotites
5.2 FTIR results
5.2.1 Granulites
5.2.1.1 Near-IR absorption
5.2.1.2 Hydrogen-related species
5.2.1.3 Water content
5.2.2 Peridotites
5.2.2.1 H-related species
5.2.2.2 Water content
5.3 IRMS results
5.4 SIMS results
5.4.1 REE contents
5.4.2 Hydrogen isotopic compositions
5.4.3 Oxygen isotopic compositions
5.4.4 Lithium contents and isotopic compositions
6 Water in the continental lower crust
6.1 Preservation of initial hydrogen information
6.2 Distribution of water within sub-grain scale
6.3 Partitioning of water between lower crustal phases
6.4 Water budget in the lower crust
6.5 Water content contrast between Precambrian and Phanerozoic lower crust
6.6 Speculation on the high electrical conductivity in the lower crust
7 Water in the deep continental lithosphere beneath the North China Craton
7.1 Preservation of initial water content in mantle minerals
7.2 Estimation of the ascent rate of xenolith/hosted alkaline basalts
7.3 Lateral variation of water content in the continental lithosphere
7.4 Vertical variation of water content between the lower crust and upper mantle
7.5 Implications on the rheological viscosity of the deep continental lithosphere
8 REE distribution and H-O-Li stable isotopes of lower crustal granulite minerals
8.1 Partitioning of REE between coexisting phases
8.2 Oxygen isotopic compositions
8.2.1 Isotopic vs. cation exchange temperatures
8.2.2 Recycled crustal materials during the petrogenesis
8.2.3 Inter-grain δ18O heterogeneities
8.3 Hydrogen isotopic compositions
8.3.1 Fractionation of H-isotopes between cpx and plag
8.3.2 Possible origins for the δD variations
8.3.3 Constraints on fluids in the continental lower crust
8.4 Lithium contents and isotopic compositions
8.4.1 Li-abundance and isotopic systematics
8.4.2 Partitioning and isotopic fractionation of Li between lower crustal minerals
8.4.3 Possible origins for δ7Li in the granulite minerals
9 Conclusions and future work