negative anomaly
1.Based on the seventh generation of International Geomagnetic Referance Field, thenondipole magnetic fields for 1900-2000 (interval is 5 years.) were calculated anddrawn, the locations and intensities of each magnetic anomaly centre at different epochwere computod and analysed, too. The distribution rangs are very large, and theintensities are very strong for the following five magnetic anomalies: Eastern Asianpositive anomaly, Oceanian negative anomaly, Southern Atlantic positive anomaly,African negative anomaly and Northern American positive anomaly.
6.Before the 9th July 1979 Liyang earthquake, beginning from mid June the vertical component at the Liyang station about 20km from the epicentral area decreased gradually to a negative anomaly. After decreasing to the lowest level in the last ten days of June, it increased quickly to a positive anomaly. Just before the tectonic event, the observational value was brought back to its initial value.
7.Chemical compositions of the lamproites are very close to the average composition of Asia lamproites and coincide with those of the west Kimberley lamproites, Australia. Their REE compositions and patterns lie within the area of world lamproites. Most lamproite samples we found exist the common characteristics of lamproites: with positive anomaly in Ba K La and Ce and negative anomaly in Ta Nb Sr and Ti.
8.Through composite analyses for the two kinds of cases, respectively, it is shown that there are positive departure of500 hpa geopotential height and negative anomaly of sea level pressure in East Asia, which meanEast--Asian winter monsoon becomes weaker in the EI Nino wintertime. The anomalous circulation situation is well analogous to the observed PNA pattern in the Aleutian and North Americanarea.
9.The different-altitudes upward continuation of the recently-surveyed aeromagnetic anomalies in central and western Qinghai Tibet plateau revealed an extremely distinct NNE trending negative magnetic anomaly zone in the eastern part of the surveyed area, i.e., in the vast area extending from Qaidam southwestward within central Qinghai-Tibet plateau.
10.Geochemical data indicate that Yajiangqiao trondhjemite, Huatan trondhjemite and Mopanshan granite, considered as component parts of Kangding complex formed in Late Archean or Palaeoproterozoic, are similar to TTG in such aspects as low Mg~#, Na-2O>K-2O, strong fractionationed REE, no or slightly negative Eu anomaly, low Yb-N, Cr, Ni, V, Nb, Ta, Ti, high Ba, and changeable Sr.
