Trace Element and Isotope Characteristics of Cenozoic Basalts around the Tanlu Fault with Implications for the Eastern Plate Boundary between North and South China: An Extended Discussion

Abstract

Deciphering the collisional tectonics between the North and South China blocks is a key to understanding the evolution of the Eurasian continent. However, no consensus exists about the North and South China collision. Three main opinions about the North and South China plate boundary east of the Tanlu fault zone, based on three sharply contrasting tectonic models, deal with the North and South China collision. Yin and Nie (1993) suggested that the North China block is separated from the South China block by the Tanlu-Sulu-ImpingingHonam zones. Li (1994) advocated a subsurface suture extending eastward approximately from Nanjing. In contrast, in earlier works (Zhang 1997, 1999), I proposed that the North and South China blocks are divided by the Tanlu-Sulu-ImjingangYanji zones and that the whole of South Korea belongs tectonically to the South China block. Recently, Chung (1999) concluded that the lithospheric mantle source region of Cenozoic basalts from the Subei basin in the eastern part of the Tanlu fault is structurally affiliated with the North China block and therefore supported Li’s (1994) model. However, the conclusion that there are distinct isotopic features of Cenozoic basalts from North and South China, which formed the basis of Chung’s view, is drawn on a geographic rather than a tectonic divide, and recent geochemical data from the North and South China basalts, along with recent geophysical investigations, are apparently incompatible with this conclusion. Here I present both isotopic and geophysical data that disagree with Chung’s (1999) conclusions.