HR: 1340h
AN: V13E-0579 [Abstracts]
TI: The Geochemical Characteristics of Volcanic Rocks in the South of Akazi, West Kunlun, Xinjiang,
China
AU: Yongguan, D
EM: dyongguan@vip.sina.com
AF: Dong Yongguan, Nanjing Institute of Geology and mineral resources, 534 East Zhongshan road., Nanjing,
JS 210016
China
AU: Kunyi, G
EM: njgkunyi@cgs.gov.cn
AF: Guo Kunyi, Nanjing Institute of Geology and mineral resources, 534 East Zhongshan road., Nanjing, JS
210016
China
AU: * Chuanlin, Z
EM: njzchuanlin@cgs.gov.cn
AF: Zhang Chuanlin, Nanjing Institute of Geology and mineral resources, 534 East Zhongshan road., Nanjing,
JS 210016
China
AB:
The volcanic rocks of south Akazi distributed from Xinjiang-tibet road to Ulutwustang of Pishan county in West Kunlun
mountain, it_s long is about 80 km and width about 20-30 km from north to south.
The volcanic rocks is a set of basic volcanic rocks (spitite-keratophyre) bearing normal sedimentary clastic rocks and
carbonate rocks, the thickness of volcanic rocks is about 470-3500m. It_s age of Rb-Sr is about 1764Ma(Wang,1987).
The low parts of the volcanic rocks is a set of basic volcanic rocks bearing marble and fine clastic rocks, and the basic
volcanic rocks occured in middle to thick lay and the thickness of single lay is nA10m to nA100m, the pillow stractures
were found in place of Xinjiang-tibet road 112km from Xinjiang to tibet, and the volcanic rocks possess marine sedimentary
characteristics. The mid part is that of clastic rocks and the bimodal volcanic rocks composed of basalt and rhyolite
occurred on the top of clastic rocks.
The chemical contents of volcanic rocks showed that the basalt of low player came from deeper place.
The geochemical characteristics of the volcanic rocks shows that the basalt is the alkali basalt, it_s crystalization
differentiation is obvious. The geochemical characteristics of microelements shows that the basic rocks and acid rocks came
from deeper place and from the same magma source.
The geochemical characteristics of rare elements indicated that light and weigh REE differentiated at middling, the
characteristics of ÝŽEu and Eu shows light positive anomaly for the most of basalt, and that shows obvious negative anomaly,
the light and weigh REE differentiated strongly for acid rock., and the volcanic rocks enriched light REE. The
characteristics above shows that basic and acid rocks may be came from the same source but from different degree of
crystalizational differentiation. The forming mechanism of volcanic rocks is that the basaltic magma formed in mantle melting
partially and occurred differentiation in the moved up process of basaltic magma, at last, rhyolite formed on the top of
volcanic rocks from acid magma.
The characteristics of microelements for basic rocks is as same as that of standard N-MORB curves, and is similar to
tholeiite-alkali intraplate basalt and indicated that the basalt formed in continental intraplate. It is showed that the
magama came from some source of transiyional mantle or enriching mantle and was similar to the oceanic ridge basalt(ORB). The
rate of Nb/U, Ce/Pb and the contents of Nb, Ce is similar to the continental crust, these characteristis above indicated
that the volcanic rocks formed in the continental intraplate environment.
The rate of Ti/V is same as that of mid ocean ridge basalt, the rate of Th/Yb, Zr/Hf, Tb/y indicated that volcanic magma
came from the source of trasitional mantle or from some kinds sources enriched mantle. The rate of Ce/Y is showed that
volcanic magma came from the source of enriched mantle which was alterated by water-bearing fluid.
DE: 1009 Geochemical modeling (3610, 8410)
DE: 1051 Sedimentary geochemistry
DE: 3610 Geochemical modeling (1009, 8410)
DE: 8410 Geochemical modeling (1009, 3610)
SC: Volcanology, Geochemistry, Petrology [V]
MN: Fall Meeting 2005