Please enter verification code
Geochemistry of Sodium Alkaline Igneous Formations in NE Vietnam: Evidence of Paleohotspot & Mesohotspot Traces
Science Research
Volume 3, Issue 2, April 2015, Pages: 38-44
Received: Feb. 25, 2015; Accepted: Mar. 12, 2015; Published: Mar. 17, 2015
Views 2797      Downloads 194
Nguyen Trung Chi, Petroleum Department, Petrovietnam University (PVU), Ba Ria City, Ba Ria- Vung Tau Province 74000, Viet Nam
Martin F. J. Flower, Department of Earth and Environmental Sciences, University of Illinois—Chicago, (UIC), USA
Article Tools
Follow on us
Researched results on geochemistry of major, trace and isotopic elements from igneous formations in NE Vietnam area have established a Sodium alkaline igneous Province (Chi Nguyen et al., 2004), which consist of a chain of alkaline igneous formations: ijolite- melteigite- jacupirangite- nepheline syenite rocks from Pia Ma massif (Tuyen Quang) toward SE distance ~200km via Bang Phuc massif (Bac Kan), and then to Ngoi Biec one (Yen Bai) towards SW~ 250km, they created a assemblage of alkaline ultramafic-mafic and nepheline syenite rocks at Viet Bac Craton, that is a part of South China Platform margin. The research on petrogenesis of the above mentioned alkaline rocks show that: 1) Alkaline ultramafic – mafic rocks and nepheline syenite has a very high content of (Na2O+K2O) from (1.94-8.4%) to (9.62-16.7%), high Al2O3 from (6.88-16.93%) to (17.2 - 24.32%) belong to both alkaline ultramafic- mafic groups and nepheline syenite rock. The P2O5 content of those 2 groups is very high (0.7- 1.10%). Agpait Index (AI) of nepheline syenite rocks < 1, but Na > K and Ca, Mg contents is high, showing nepheline syenite is the miaskitic type. The total content of (REE+Y) varies from 164÷432ppm with Ce/Y=2.83÷6.64,(La/Sm)N=4.12,(Ce/Sm)N=2.64, (Yb/Lu)N = 1.27, Eu/Eu*= 0.1-0.28. However, the range isotope content of Sr and Nd in whole rocks of Pia Ma and that of Cho Don are different, in Pia Ma: 0.705846 ÷ 0.706419 and 0.511831 ÷ 0.511975 with value of εNd = - 2.35 ÷ +0.12 belong to EM1- type and aged in 519 ± 40Ma (Early Cambrian); in Cho Don: 0.709893 ÷ 0.718356 and 0.511854 ÷ 0.512010 with value of εNd = - 9.79 to - 2.9 belong to EM2-type and aged in 231 ± 23 Ma (Late Triassic ). 2) The geochemical characteristics of trace elements and isotope from above rocks indicated that, have fractional crystallization of a mixed magma liquid with composition of nephelinite derived from partial melting of depleted mantle source. This magma source may intruded into crust at Pia Ma in Early Paleozoic (Paleohotspot trace) and then at Cho Don and Ngoi Biec in Late Triassic (Mesohotspot traces) as they pass over "hotspot" in mantle. Possibly, this hotspot reactivated in Eocen and by the way to open the East Sea. The movenment speed of South China Plate towards North is about 0,7- 2,2 mm/year.
Sodium Alkaline Igneous, Ijolite-Melteigite-Jacupirangite, Nepheline Syenite, Hotspot Traces
To cite this article
Nguyen Trung Chi, Martin F. J. Flower, Geochemistry of Sodium Alkaline Igneous Formations in NE Vietnam: Evidence of Paleohotspot & Mesohotspot Traces, Science Research. Vol. 3, No. 2, 2015, pp. 38-44. doi: 10.11648/
Chi N.T et al., 2004. Petrology and Metallogeny of alkaline magmatic formations in North Vietnam. Concluded report of Project, Documented in Institute of Geological Information- Archives and Museum. Hanoi (558p.)
Condie K.C., 1989. Plate tectonic and Crust Evolution (Third edition). Pergarmon Press, New York.
Deer W. A., Howie R. A. and Zussman J. 1992: An introdution to the rock - forming minerals. Longman scientific & technical.
Edgar A.E., 1987. The genegis of alkaline rocks magmas with emphasis on their sources regions: Inference from experimental studies. In : Fitton and Upton. 29-52
Faure G., 1986. Principles op Isotope Geology (Second edition).Wiley, New York. 589 p.
Faure G., 2001. Origin of Igneous Rocks- The isotopic Evidence. Springer. 496 P.
Henderson P. (ed).,1984. Rare Earth Element Geochemistry, Developments in Geochemistry 2. Elservier. New York. 150 p.
Le Bas M.J.,et al., 1987. Nephelinites and carbonatites. In : Alkaline Rocks. Fitton J.G. and Upton B.G.J., (eds)., Geol, Soc. Spe, Publ. 30.
MacKenzie,D.P., and Weiss,N., 1975.Speculation on the thermal and tectonic history of the Earth.Geophys. J.Roy. Astro. Soc., 42, 131-174
Metcalfe, I. 1996. IGCP Lecture: Gondwana dispersion & Asian accretion. The Australian Geologist, No. 98, pp. 23-29.
Sorensen, H. (ed),. 1979. Alkaline Rocks. Wiley, New York. 622p
Wilson,J.T.,1963. A Possible origin of the Hawaiian islands. Can.J. Phys. 41, 863-870
Science Publishing Group
1 Rockefeller Plaza,
10th and 11th Floors,
New York, NY 10020
Tel: (001)347-983-5186