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Cenozoic volcamc rocks widespread in eastern China constitute an important part of the circum--Pacificvolcanic belt. This paper presents more than 150 K--Ar dates and a great deal of petrochemical analysis data from theCenozoic volcanic rocks distributed in Tengchong, China’s southeast coast, Shandong, Hebei, NeiMonggoland Northeast China. An integrated study shows that ubiquitous but uneven volcanic activities prevailed fromthe Eogene to the Holocene, characterized as being multi-episodic and multicycled. For example, in thepaleocene (67--58Ma),Eocene(57-37.5Ma), Miocene(22-18,16-19Ma),Pliocene (8--3Ma), and EarlyPleistocene--Middle Pleistocene(l.2-1.5Ma) there were upsurges of volcanism, while in the Oligocene therewas a repose period. In space, the older Eogene volcanic rocks are distributed within the region or in thecentral part of the NE--NNE-striking fault depression, while the younger Neogene and Quaternary volcanicroeks are distributed in the eastern and western parts. Petrologically, they belong essentially to tholeiite-series and alkali-series basalts, with alkalinity in the rocks increasing from old to young. The above regularities are controlled by both global plate movement and regional inherent tectonicpattern.
This paper presents more than 150 K - Ar dates and a great deal of petrochemical analysis data from theCenozoic volcanic rocks distributed in Tengchong, China’s southeast coast, An integrated study shows that ubiquitous but uneven volcanic activities prevailed from the Eogene to the Holocene, characterized as being multi-episodic and multicycled. For example, in the paraleocene (67-58Ma), Eocene (57- 37.5Ma), Miocene (22-18, 16-19Ma), Pliocene (8-3Ma), and EarlyPleistocene - Middle Pleistocene (1.2-1.5Ma) there were upsurges of volcanism, while in the Oligocene therewas a repose period. In space, the older Eogene volcanic rocks are distributed within the region or in the central part of the NE - NNE-striking fault depression, while the younger Neogene and Quaternary volcanic roeks are distributed in the eastern and western parts. gically, they belong essentially to tholeiite-series and alkali-series basalts, with alkalinity in the rocks increasing from old to young. The above regularities are controlled by both global plate movement and regional inherent tectonicpattern.