Mineral Micro-Geochemistry Constraints on Petrogenesis and Genesis of Gold Deposit

Minerals respond texturally and compositionally to changing magmatic environments and preserve a wealth of information regarding magmatic processes and compositions in their crystal-growth stratigraphy. This book reports the detailed petrography and in-situ geochemistry of the clinopyroxene phenocrysts of the mafic dykes in the Jiaodong Peninsula, southeastern North China Craton, including in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents with further constraints on the petrogenesis and geodynamics of the mafic dykes. Systematic analyses of mineralogical, major, and trace elements, Sr–Nd isotopes, and in-situ S isotopes on the pyrite of the main gold-bearing mineral assemblages and visible gold were conducted, aiming to explore the source of ore-forming materials and the process of Au element migration and deposition. The geodynamic setting of mineralization in the studied region is also summarized. Acknowledgments 5 Contents 6 1 Introduction 8 References 12 2 Geological Setting 17 2.1 North China Craton 17 2.2 Jiaodong Gold Province 18 2.2.1 Strata 20 2.2.2 Structure 23 2.2.3 Intrusions Rocks 24 2.2.4 Dyke Swarms 26 2.2.5 Ore Resources 26 References 27 3 Micro-Geochemistry of Clinopyroxene of the Mafic Dykes in the Jiaodong Peninsula: Implications for Petrogenesis and Geodynamic 30 3.1 Introduction 30 3.2 Petrology of the Early Cretaceous Mafic Dykes in the Jiaodong Peninsula 31 3.3 Emplacing Age of the Early Cretaceous Jiaodong Mafic Dykes 34 3.4 Petrogenesis of the Mafic Dykes 36 3.4.1 Geochemical Compositions of the Jiaodong Mafic Dykes 36 3.4.2 Limited Crustal Contamination 36 3.4.3 Fractional Crystallization 48 3.4.4 Magma Mixing: Evidence from Reversely Zoned Clinopyroxene Phenocrysts 50 3.4.5 Nature of the Mantle Source of the Mafic Dykes 70 3.5 Mantle Source Were Enriched by the Subduction-Related Metasomatism 72 3.5.1 Enriched Features of High-Mg Clinopyroxene Phenocrysts 73 3.5.2 High H2O Contents of Clinopyroxene Phenocrysts 81 3.6 Lithospheric Mantle Was Changed During Mesozoic 89 3.6.1 Nature of the Plaleoproterozoic Lithospheric Mantle 89 3.6.2 Lithospheric Mantle Were Enriched by Metasomatism of the Paleo–Pacific Plate Subduction During Mesozoic 96 3.7 Thinning of the Lithosphere Beneath Jiaodong Peninsula as a Result of Continuous Thermo-Mechanical Erosion 98 3.7.1 The Variation of Lower Continental Crust Beneath Jiaodong Peninsula 99 3.7.2 The Thinning of Lithospheric Mantle Beneath Jiaodong Peninsula 126 References 128 4 Micro-Geochemistry of Pyrite and Gold Mineral in Jiaodong Gold Deposits: Implications for Genesis of Gold Deposit 140 4.1 Introduction 140 4.2 Ore Deposit Geology 142 4.2.1 Linglong Gold Orefield 142 4.2.2 Jiaojia Gold Deposit 144 4.2.3 Sanshandao-Xinli Deposit 146 4.3 The Micro-Geochemical Characteristics of Gold from “Jiaojia-Type” Gold Deposit: Implications for Sources of Ore-Forming Minerals and Fluids of Sanshano-Xinli Gold Deposit 149 4.3.1 Mineralogical Characteristics 149 4.3.2 Micro-Geochemical Characteristics 151 4.3.3 Geological Significance of Elements in Silver-Gold Minerals 157 4.3.4 Sources of Ore-Forming Minerals and Fluids 161 4.4 The Micro-Geochemical Characteristics of Pyrite in the Linglong-Type and Jiaojia-Type Gold Deposits in the Jiaodong Gold Province: Implications for genesis of gold deposit 162 4.4.1 Fluid Inclusions 162 4.4.2 Geochemical Composition of Pyrite 168 4.4.3 Features and Sources of Ore-Forming Fluids 170 4.4.4 Source of Ore-Forming Materials 179 4.4.5 Gold Transport and Deposition 197 4.4.6 Deposit Genesis 198 References 200