The granites in Xinchenggou area of Dongning County are located on the active continental margin of eastern part of Xing'anling-Mongolian orogenic belt. In this paper, petrologic and element geochemical studies were carried out for granites in Xinchenggou area, Dongning County. Major element geochemistry shows that the rocks are calc-alkaline and I-type granites, and are also characterized by enrichment of alkali, relative enrichment of potassium and S-type syn-collisional granites. The Rittman index δ is from 1.41 to 2.11. The alumina saturation index ACNK is from 1.02 to 1.20. REE concentrations are low ( ΣREE=72.35×10 -6~217.64×10 -6 ) and show obvious differentiation between LREE and HREE ( LaN/YbN=2.74~11.37 ), with apparent Eu negative anomalies ( δEu=0.14~0.83 ), and the abnormality of δCe (δCe =0.96~1.11) is not apparent. In addition, the rock mass is relatively poor in such elements as Nb, Ta, P and Ti, and rich in Rb, Ba and K . w(Nb)/w(Ta) ratios of trace elements are less than 16.2, suggesting that the magmas were formed by partial melting of the crust. The magmas were formed by collision between the North China plate and Siberia plate in Late Paleozoic-Early Mesozoic period and subduction of the paleo-Pacific plate towards the east edge of Eurasia in Late Triassic. The magmas also had the characteristics of multi-stages and complex genesis. Geophysical and geochemical anomaly, geochemical characteristics, and geochemical ore parameters indicate that this area has prospecting potential for epithermal-type Au-Ag-Cu deposits.
Kobayashi F . Middle Permian biogeography based on fusulinacean faunas[G] //Ross C A, Ross J R P, Brenckle P L.Late paleozoic foraminifera: Their biogeography, evolution, and paleoecology, and the mid-carboniferous boundary.Cushman Foundation for Foraminiferal Research, Special Publication 36, 1997: 73-76.
[6]
Kobayashi F . Palaeogeographic constraints on the tectonic evolution of the Maizuru Terrane of Southwest Japan to the eastern continental margin of South China during the Permian and Triassic[J]. Palaeogeogr Palaeoclimatol Palaeoecol, 2003,195:299-317.
doi: 10.1016/S0031-0182(03)00363-8
[7]
Zhang K J . North and South China collision along the eastern and southern North China margins[J]. Tectonophysics, 1997,270(1-2):145-156.
doi: 10.1016/S0040-1951(96)00208-9
[8]
Zhang K J . Granulite xenoliths from Cenozoic basalts in SE China provide geochemical fingerprints to distinguish lower crust terranes from the North and South China tectonic blocks: comment[J]. Lithos, 2004,73(1):127-134.
doi: 10.1016/j.lithos.2003.10.005
[9]
Li S Z, Jahn B M, Zhao S J , et al. Triassic southeastward subduction of North China Block to South China Block: Insights from new geological, geophysical and geochemical data[J]. Earth-Science Reviews, 2017,166:270-285.
doi: 10.1016/j.earscirev.2017.01.009
Middlemost Eric A K . Naming materials in the magma/igneous rock system[J]. Earth-Science Reviews, 1994,37:215-224.
doi: 10.1016/0012-8252(94)90029-9
[13]
Peccerillo R, Taylor S R . Geochemistry of Eocene calc-alkaline volcanic rocks from the Kastamonu area, Northern Turkey. Contrib[J]. Mineral Petrol, 1976,58:63-81.
doi: 10.1007/BF00384745
[14]
Middlemost Eric A K . Magmas and magmatic rocks: an introduction to igneous petrology[M]. London: Longman, 1985, 1-266.
Sun S S, McDonough W F . Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and processes[J]. Geological Society London Special Publications, 1989,42:313-345.
doi: 10.1144/GSL.SP.1989.042.01.19
Wu F Y, Jahn B M, Wilde S A , et al. Highly fractionated I-type granites in NE China(I): geochronology and petrogenesis[J]. Lithos, 2003,66:241-273.
doi: 10.1016/S0024-4937(02)00222-0
Wang Y J, Zhang Y, Fan W M , et al. Numerical modeling of the formation of Indo-Sinian peraluminous granitoids in Hunan Province: Basaltic underplating versus tectonic thickening[J]. Science in China:Series D, 2002,45(11):1042-1056.
doi: 10.1007/BF02911241
pmid: 23189623
[28]
Inger S, Harris N . Geochemical constraints on leucogranite magmatism in the Langtang Valley,Nepal Himalaya[J]. Journal of Petrology, 1993,34:345-368.
doi: 10.1093/petrology/34.2.345
Pearce J A, Harris N B W, Tindle A G . Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J]. Journal of Petrology, 1984,25(4):956-983.
doi: 10.1093/petrology/25.4.956
Collins W J, Beams S D, White A J R , et al. Nature and origin of A-type granites with particular reference to southeastern Australia[J]. Contributions to Mineralogy and Petrology, 1982,80(2):189-200.
doi: 10.1007/BF00374895
Hofmann A W . Chemical differentiation of the earth: the relationship between mantle, continental crust, and oceanic crust[J]. Earth and Planetary Science Letters, 1988,90:297-314.
doi: 10.1016/0012-821X(88)90132-X
[38]
Batchelor R A, Bowden P . Petrogenetic interpretation of granitoid rock series using multicationic parameters[J]. Chemical Geology, 1985,48(1/4):43-45.
doi: 10.1016/0009-2541(85)90034-8
