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

This book reports on the petrography and geochemistry of clinopyroxene phenocrysts in mafic dykes in the Jiaodong Peninsula, southeastern North China Craton, including major elements, trace elements, Sr isotopic compositions, and H2O contents. It also explores the source of ore-forming materials and the process of Au element migration and deposition in the region's geodynamic setting.

Format: Paperback / softback
Length: 203 pages
Publication date: 12 March 2022
Publisher: Springer Verlag, Singapore

Minerals exhibit remarkable textural and compositional responses to evolving magmatic environments, serving as invaluable archives of information about magmatic processes and compositions. This comprehensive book presents a detailed petrography and in-situ geochemistry study of clinopyroxene phenocrysts within mafic dykes in the southeastern North China Craton. It includes in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents, providing further insights into the petrogenesis and geodynamics of these mafic dykes. Systematic analyses of mineralogical, major, and trace elements, Sr–Nd isotopes, and in-situ S isotopes on pyrite, the primary gold-bearing mineral assemblage, and visible gold are conducted to explore the origins of ore-forming materials and the mechanisms of Au element migration and deposition. Additionally, a summary of the geodynamic setting of mineralization in the studied region is provided.

Introduction:
The Jiaodong Peninsula, located in southeastern North China Craton, is a region of significant geological interest due to its abundance of mafic dykes. These dykes, characterized by their high-temperature and high-pressure conditions, are believed to have played a crucial role in the formation and evolution of the craton. Clinopyroxene phenocrysts, which are commonly found within these dykes, provide valuable insights into the magmatic processes and compositions associated with their formation.

Petrography and Geochemistry of Clinopyroxene Phenocrysts:
The petrography study involves the detailed examination of clinopyroxene phenocrysts using optical microscopy, electron microprobe analysis, and other advanced techniques. This analysis helps in identifying the mineralogical characteristics, such as crystal structure, texture, and chemical composition, of the phenocrysts. In-situ geochemistry, on the other hand, involves the direct measurement of major elements, trace elements, Sr isotopic compositions, and H2O contents in the clinopyroxene phenocrysts. This approach provides valuable information about the magmatic environment and the processes that led to the formation of the clinopyroxene phenocrysts.

In-situ Determinations of Major Elements, Trace Elements, Sr Isotopic Compositions, and H2O Contents:
The in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents in the clinopyroxene phenocrysts provide crucial information about the petrogenesis and geodynamics of the mafic dykes. Major elements, such as Si, Al, Fe, and Mg, are important indicators of the source rock and the degree of melting that occurred during the magmatic process. Trace elements, such as Cr, V, Ni, and Co, can provide insights into the composition of the mantle source and the processes of partial melting and fractional crystallization. Sr isotopic compositions, particularly Sr/Sr ratios, can help in tracing the provenance of the magma and the tectonic setting of the region. H2O contents can provide information about the temperature and pressure conditions during the crystallization of the clinopyroxene phenocrysts.

Constraints on the Petrogenesis and Geodynamics of the Mafic Dykes:
The in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents in the clinopyroxene phenocrysts provide further constraints on the petrogenesis and geodynamics of the mafic dykes. These constraints help in refining the existing models and understanding the processes that led to the formation of these dykes. For example, the presence of certain trace elements, such as Cr and V, in the clinopyroxene phenocrysts suggests that the mantle source was contaminated by crustal material during the partial melting process. The Sr/Sr ratios of the clinopyroxene phenocrysts can help in determining the tectonic setting of the region, as they are sensitive to the temperature and pressure conditions during the magmatic process.

Systematic Analyses of Mineralogical, Major, and Trace Elements, Sr–Nd Isotopes, and In-situ S Isotopes on Pyrite:
In addition to the in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents, systematic analyses of mineralogical, major, and trace elements, Sr–Nd isotopes, and in-situ S isotopes on pyrite are conducted. Pyrite is the primary gold-bearing mineral assemblage in the studied region, and its mineralogy and geochemistry can provide insights into the source of ore-forming materials and the process of Au element migration and deposition. Sr–Nd isotopes, in particular, can help in tracing the provenance of the gold and the tectonic setting of the region. In-situ S isotopes can provide information about the temperature and pressure conditions during the formation of the gold deposits.

Geodynamic Setting of Mineralization:
The geodynamic setting of mineralization in the studied region is also summarized in this book. The Jiaodong Peninsula is located in the eastern part of the North China Craton, which is a continental craton characterized by thickened continental crust and extensive orogenic belts. The mafic dykes in the Jiaodong Peninsula are believed to have formed during the late Paleozoic to early Mesozoic period as a result of the collision of the Indian Plate with the Eurasian Plate. The collision led to the uplift and deformation of the crust, which resulted in the formation of high-temperature and high-pressure conditions suitable for the formation of mafic dykes.

Conclusion:
In conclusion, this book presents a comprehensive petrography and in-situ geochemistry study of clinopyroxene phenocrysts within mafic dykes in the southeastern North China Craton. The in-situ determinations of major elements, trace elements, Sr isotopic compositions, and H2O contents provide valuable insights into the petrogenesis and geodynamics of these mafic dykes. Systematic analyses of mineralogical, major, and trace elements, Sr–Nd isotopes, and in-situ S isotopes on pyrite and visible gold further explore the origins of ore-forming materials and the processes of Au element migration and deposition. The geodynamic setting of mineralization in the studied region is also summarized, providing a framework for understanding the tectonic evolution of the craton.

Weight: 332g
Dimension: 235 x 155 (mm)
ISBN-13: 9789811610240
Edition number: 1st ed. 2021