HR: 08:20h
AN: T31E-02    [Abstracts]
TI: Geochemistry of basalts from Northeast China
AU: Chen, Y
EM: yangcz@umich.edu
AF: The University of Michigan, Department of Geological Sciences, Ann Arbor, MI 48109-1063 United States
AU: * Zhang, Y
EM: youxue@umich.edu
AF: The University of Michigan, Department of Geological Sciences, Ann Arbor, MI 48109-1063 United States
AB: One of the notable areas of intraplate volcanism is northeast China. In an area of about two million square kilometers, there are numerous volcanic fields (about 600 volcanos known, Liu, 1999) with ages from Late Cretaceous (80 Ma) to recent (the most recent eruption was 300 years ago). Individual volcanic centers are usually small and a volcanic field typically consists of several to tens of volcanic centers. In this report, we review petrological and geochemical data in literature, present our new data, examine compositional correlations for this vast volcanic province, and explore possible controls of geochemistry by other parameters such as lithosphere thickness, crustal thickness and heat flow. Preliminary results show that not all data are consistent, probably reflecting analytical uncertainties of various labs. Isotopically, the basalts range from depleted mantle to bulk silicate Earth. Some elemental concentrations are correlated, and the correlation is strong along one linear belt of volcanic fields. There are systematic geochemical differences between alkali basalts from northeast China and intraplate alkali basalts from east Australia or from Hawaii. Basalt chemistry seems to vary systematically along a linear volcanic belt. The variations can be roughly explained by varying the degree and depth of mantle partial melting (such as the presence or absence of garnet), and might be related to lithosphere thickness. More work is in progress to examine basalt chemistry and other parameters and to understand the significance of the correlations and variations.
DE: 8110 Continental tectonics--general (0905)
DE: 7218 Lithosphere and upper mantle
DE: 3640 Igneous petrology
DE: 1020 Composition of the crust
DE: 1065 Trace elements (3670)
SC: Tectonophysics [T]
MN: 2004 AGU Fall Meeting