Wen Zeng, Hanwen Zhou, Zhengxiang Li, Guangfu Xing, Zengqiu Zhong, Xilin Zhao. The Evolution of the Metamorphic Series in the NW Fujian Province, the NE Cathaysia Block[A]. Science Press, Beijing, 2016: 1-119， ISBN：978-7-03-050615-3

Preface

This book focuses on the Paleoproterozoic to Late Paleozoic basement evolution of the metamorphic rocks scattered in the NW Fujian Province, the NE Cathaysia Block the southeastern area of South China. Field observation, systematic sampling and petrographic investigation combined with of whole rock geochemistry, zircon U-Pb, Lu-Hf isotopes, trace elements, amphibole and biotite ⁴⁰Ar/³⁹Ar analyses and mineral chemistry study were applied in this project to determine the nature, ages and relations of the leucosomes, felsic paragneiss and mafic metamorphic rocks in study area and their implications to the reconstruction of the Precambrian Rodina Supercontinent.

Following conclusions are made:

1. Based on this study, according to their metamorphism and deformation characteristics, the metamorphic rock series in the study area can be divided into two types, moderately to strongly metamorphosed rock series that experienced ductile deformation and moderately metamorphosed rock series that have experienced ductile deformations. New La-ICPMS U-Pb zircon ages presented here and in previous study suggest that the original litho-stratigraphy should be abandoned and the terminology “Complex” should be used instead of “Group” and “Formation” for the high grade metamorphic rock series in northwestern Fujian , where the protoliths were strongly reworked by Early Paleozoic tectono-thermal events.

2. Obvious zircon U-Pb age peaks of ~1800 Ma suggest that the protoliths of the Cathaysia Block be comparable to the basements of North America rather than those of Eastern India and East Antarctica . Although the peaks of ~1800 Ma are also present in Western Australia , their ¹⁷⁶Hf/¹⁷⁷Hf ratios (0.280706 - 0.281510) are apparently lower than those of zircons from SW Cathaysia (0.281515 - 0.282098) and from this study (0.281232 - 0.282213, NE Cathaysia). Besides, detrital zircons in Cathaysia and NW Yangtze indicate significant juvenile input during Paleo- to Mesoproterozoic according to the zircon Hf isotopes, which are distinctly different from Western   Australia . These evidences suggest that the basement of the Cathaysia share similarities with that of North  America , lending support for the Rodinia configuration proposed by Li et al. (2008), in which Cathaysia was next to western Laurentia before and during the late Mesoproterozoic assembly of Rodinia.

3. The protoliths of the felsic paragneiss in the NW Fujian area are immature sediments, consisting of greywacke, arkose and lithic arenite compositions. The significant input of the paragneiss protolith was dominantly formed by several magmatic events during Neoproterozoic (820 ± 6 Ma, 780 ± 6 Ma, 776 ± 6 Ma, 758 ± 3 Ma, 740 ± 8 Ma and 722 ± 9 Ma), probably deposited not early than middle Neoproterozoic (~680 Ma). Many metamorphic rocks contain 0.99 - 0.72 Ga detrital magmatic zircons, which are interpreted as reflecting the tectono-thermal events related to the assembly and break-up of the Rodinia supercontinent during the Neoproterozoic.

4. In this study, new La-ICPMS U-Pb anatectic zircon data from the NW Fujian area suggest that the strong and widespread tectono-thermal events were related to the orogeny probably having started during the Middle Cambrian and lasted until the Middle Devonian, consisting of at least three main episodes (~473 Ma, ~445 Ma, ~423 Ma), with major orogeny events (including syn- to post-orogenic melting) constrained between ~473 Ma and ~407 Ma in the NE Cathaysia, and between ~468 Ma and ~415 Ma in the SW Cathaysia. The age peaks in the Cathaysia Block (ca. 488, 471, 455, 440 and 415 Ma) are within the age range of the Qinling-Tongbai-Dabie orogen during 512 - 406 Ma. This suggests a possible linkage or interaction of the two orogens.

5. The duration of the “Caledonian” orogeny in the NW Fujian area was no shorter than ~50 Myr, starting at ~473 Ma (~Early Ordovician) or earlier, and terminating at ~423 Ma (~Middle Silurian) or later. The “Caledonian” orogenic event in the Cathaysia Block was likely due to an intracontinental collision rather than the subduction of oceanic crust or arc-continental collision. Considering the inhomogeneous cooling paths for the Tianjingping, the Jiaoxi and Mayuan complexes, and different time restraint of the widespread anatectic and magmatic events occurred in different places, the “Caledonian” tectono-thermal events in the Cathaysia Block might vary between different segments of the orogen.

This book would not have been possible without the contributions off several people. To all of these people, I wish to express my gratitude. first and foremost, I would like to thank my parents for their parental guidance and support for my education. Special thanks go to my supervisor Prof. Zengqiu Zhong for taking me on since I was an undergraduate student, and for his supervision and direction. His invaluable advice and assistance in how to systematically characterize a small yet complicated geological outcrop have contributed to my fascination and love for uncovering the evolution history of the Cathaysia Block. I also thank Prof. Hanwen Zhou and A/Prof. Li Zhang for providing thorough, detailed and constructive reviews on my papers. I am particularly grateful to my supervisor Prof. Zheng-Xiang Li of Curtin University of Technology for his great help in completing the book. I appreciate the time that he spent revising the text, talking through ideas and teaching me about geochronology and tectonics. Prof. Ian Fitzsimons and Prof. Simon Wilde are gratefully acknowledged for reviewing and commenting on my writing of both the research proposal and final book chapters. I would like to extend my thanks to Xinqian Lv and Chunzhong Li, who provided warm hospitality and logistic support for the field work in northwestern Fujian Province.

Many people provided invaluable helps to my analytical work including advices, supports and helps with analytical procedures. They are sincerely thanked here. These include Yongsheng Liu, Zhaochu Hu, Haihong Chen, Keqing Zong, Chunlin Tong and Changgui Gao of the State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosiences (Wuhan), Hujun Gong, Xiaoming Liu, Honglin Yuan, Mengning Dai and Chunrong Diwu of the State Key Laboratory of Continental Dynamics, Northwest University, Pete Kinny, Alan Kennedy, Elaine Miller, Fred Jourdan, Chris Clark, Katy Evans, Hao Gao and Min Gao of Curtin University of Technology, and Janet Muhling of the University of Western Australia. I also thank Prof. Wu Yuanbao and Qiang Wang for the helpful discussions on U-Pb ages and Hf isotopes. I wish to express my gratitude to fellow students Rui Liu, Hua Xiang and Song Jin who participated in the fieldwork and discussions, and assisted with sample preparation and some analyses. I also wish to thank my friends Jiawen Niu, Mahbubul Ameen, Jinrong Wang, Jing Wan, Min Peng, Jing Wang and Xiaochi Liu, Cheng Lei for giving me confidence and guiding me through at times of doubt and despair.

Financial supports for the project came from the National Natural Science Foundation of China (grant No. 40372094 and 41602058), the Opening Foundation of State Key Laboratory of Continental Dynamics, Northwest University (grant No. 06LCD12), the Bureau of Land and Resources of Zhejiang Province (grant No. 2004005), China Geological Survey (grant No. 12120113070800 and Nandi [2016] 02-15), the Australian Research Council (grant No. DP0770228) that supported the analytical costs in Australia , a Curtin University CIPRS scholarship, a top-up scholarship from Curtin’s The Institute for Geoscience Research (TIGeR), and a visiting scholarship from the China Scholarship Council. All these support are gratefully acknowledged.