New zircon U-Pb ages for erratic emplacement of 2213-2130 Ma Paleoproterozoic calc-alkaline I-type granitoid rocks in the Lawra Volcanic Belt of Northwestern Ghana, West Africa

doi:10.1016/j.precamres.2014.08.009

	New zircon U-Pb ages for erratic emplacement of 2213-2130 Ma Paleoproterozoic calc-alkaline I-type granitoid rocks in the Lawra Volcanic Belt of Northwestern Ghana, West Africa
	Sakyi, Patrick Asamoah 1; Su, Ben-Xun 2,3; Anum, Solomon 4; Kwayisi, Daniel 1; Dampare, Samuel Boakye 5; Anani, Chris Y.1; Nude, Prosper M.1
刊名	PRECAMBRIAN RESEARCH
	2014-11-01
卷号	254 页码:149-168
关键词	Birimian Granitoids Geochronology Lawra belt Subduction Volcanic Arc
ISSN号	0301-9268
DOI	10.1016/j.precamres.2014.08.009
文献子类	Article
英文摘要	Paleoproterozoic Birimian granitoid rocks from the Lawra volcanic belt of northwestern Ghana have been analyzed for their major, trace, REE concentrations and their zircon U-Pb age. Based on the mineral assemblages, the calc-alkaline, metaluminous to weakly peraluminous I-type granitoids were classified as: (1) gneissic biotite granite, (2) hornblende granodiorite, (3) biotite granite, (4) two-mica granite and (5) pyroxene hornblende gneiss. The high La-N/Yb-N (similar to 4-146) values of the granitoids, characterized by enriched LREE pattern and flat to depleted HREE pattern ((Dy/Yb)(N) = 0.95-3.47), is typical of rocks derived from an evolved magma or partial melting of the depleted mantle. Similarly, the slightly negative Sr- and Eu-anomalies indicate varying degrees of plagioclase fractionation. Their high but varying SiO2 contents (58.1-76.1 wt.%), K2O/Na2O ratios (0.17-1.2) and (FeO + Fe2O3)/MgO ratios (0.98-4.02), and low Ce and Ti suggest that they are volcanic arc granites (VAG). The granitoids have zircon U-Pb ages between 2130.8 +/- 9.5 Ma and 2213 +/- 76 Ma, and preclude the contamination of the juvenile Birimian crust by notable amounts of reworked Archaean crustal material. However, these ages spanning 81 Ma were recorded by all the rock types in the study area, with no distinct age difference among them. Accordingly, the area could be described as an undifferentiated terrain that experienced erratic emplacement of pulses of granitic magma during the period. Furthermore, the oldest ages of 2211 Ma and 2213 Ma recorded in this study suggest that the emplacement of Birimian granitoids in Ghana may have commenced much earlier than previously reported in the literature. The results demonstrate the juvenile character of the granitoid rocks. We therefore infer that the Birimian granitoids of the Lawra volcanic belt formed from large-scale crustal growth process with large amounts ofjuvenile crust formed from the depleted mantle in an island arc environment. (C) 2014 Elsevier B.V. All rights reserved.
WOS关键词	ARCHEAN-PROTEROZOIC BOUNDARY ; RARE-EARTH-ELEMENTS ; NORTH CHINA CRATON ; LACHLAN FOLD BELT ; A-TYPE GRANITES ; CRUSTAL EVOLUTION ; TRACE-ELEMENT ; 2.1 GA ; SOUTHEASTERN AUSTRALIA ; BIRIMIAN SUPERGROUP
WOS研究方向	Geology
语种	英语
出版者	ELSEVIER SCIENCE BV
WOS记录号	WOS:000343786400009
资助机构	National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011) ; National Natural Science Foundation of China(41173011)
内容类型	期刊论文
源URL	[http://ir.iggcas.ac.cn/handle/132A11/85910]
专题	中国科学院地质与地球物理研究所
通讯作者	Sakyi, Patrick Asamoah
作者单位	1.Univ Ghana, Dept Earth Sci, Legon, Ghana 2.Chinese Acad Sci, Inst Geol & Geophys, State Key Lab Lithospher Evolut, Beijing 100029, Peoples R China 3.Univ Hong Kong, Dept Earth Sci, Hong Kong, Peoples R China 4.Geol Survey Dept, Koforidua, Eastern Region, Ghana 5.Univ Ghana, Sch Nucl & Allied Sci, Kwabenya, Ghana
推荐引用方式 GB/T 7714	Sakyi, Patrick Asamoah,Su, Ben-Xun,Anum, Solomon,et al. New zircon U-Pb ages for erratic emplacement of 2213-2130 Ma Paleoproterozoic calc-alkaline I-type granitoid rocks in the Lawra Volcanic Belt of Northwestern Ghana, West Africa[J]. PRECAMBRIAN RESEARCH,2014,254:149-168.
APA	Sakyi, Patrick Asamoah.,Su, Ben-Xun.,Anum, Solomon.,Kwayisi, Daniel.,Dampare, Samuel Boakye.,...&Nude, Prosper M..(2014).New zircon U-Pb ages for erratic emplacement of 2213-2130 Ma Paleoproterozoic calc-alkaline I-type granitoid rocks in the Lawra Volcanic Belt of Northwestern Ghana, West Africa.PRECAMBRIAN RESEARCH,254,149-168.
MLA	Sakyi, Patrick Asamoah,et al."New zircon U-Pb ages for erratic emplacement of 2213-2130 Ma Paleoproterozoic calc-alkaline I-type granitoid rocks in the Lawra Volcanic Belt of Northwestern Ghana, West Africa".PRECAMBRIAN RESEARCH 254(2014):149-168.