Mesozoic mafic dikes from the Shandong Peninsula, North China Craton: Petrogenesis and tectonic implications

Abstract

Mesozoic mafic dikes are widely distributed in Luxi (Mengyin and Zichuan) and Jiaodong regions of the Shandong Peninsula, China, providing an opportunity of investigating the nature of the lost lithospheric mantle beneath the North China Craton (NCC). The mafic dikes are characterized by strong depletion in high field strength elements (HFSE), enrichment in light rare earth elements (LREE), highly variable Th/U ratios, high initial ( 87 Sr/ 86 Sr) i (0.7050-0.7099) and negative ε Nd (T) (-6.0 to -17.6). They were derived from melting of metasomatized portions of the subcontinental lithospheric mantle, followed by fractionation of clinopyroxenes. The similarity in Nd isotopic compositions between the Mengyin gabbro dikes and the Paleozoic peridotite xenoliths suggests that ancient lithospheric mantle was still retained at 120 Ma below Mengyin, although the ancient lithospheric mantle in many other places beneath NCC had been severely modified. There might be multiple enrichment events in the lithospheric mantle. An early-stage (before or during Paleozoic) rutilerich metasomatism affected the lithospheric mantle below Mengyin, Jiaodong and Zichuan. Since then, the lithospheric mantle beneath Mengyin was isolated. A late-stage metasomatism by silicate melts modified the lithospheric mantle beneath Jiaodong and Zichuan but not Mengyin. The removal of the enriched lithospheric mantle and the generation of the mafic dikes may be mainly related to the convective overturn accompanying Jurassic-Cretaceous subduction of the paleoPacific plate.

Petrogenesis of Early Cretaceous Magmatism in Eastern China and the Gyeongsang Basin, Korean Peninsula

“…북중 국지괴 동측에 분포하는 백악기초기(약 144-100 Ma) 화성암은 피크라이트(picrite)-현무암-현무암질 안산암 및 황반암(lamprophyre)의 분출암 (Qiu et al, 2002;Yang et al, 2004;Guo et al, 2005Guo et al, , 2013Liu et al, 2006;Gao et al, 2008;Ma et al, 2014a, b)과 반려암-섬록암-몬조니암-섬장암-화강암 및 휘록암의 관 입암체 (Xu et al, , 2006Chen et al, , 2004Zhang et al, 2004Zhang et al, , 2005Zhang et al, , 2010Zhang et al, , 2012Wu et al, 2005;Yang et al, 2006Yang et al, , 2012aLiu et al, , 2009 Guo et al, 2004;Wang et al, 2005)과 반려암-섬록암-몬조니암-섬장암-화강암 및 휘록암의 관입암체 (Jahn et al, 1999;Yang et al, 2005a;Guo et al, 2006Guo et al, , 2014Huang et al, 2006Huang et al, , 2007Wang et al, 2007;Zhao et al, 2005Zhao et al, , 2007aLiu et al, 2008b;Tang et al, 2008b;Zhang et al, 2010Zhang et al, , 2012He et al, 2011He et al, , 2013)로 구성되어 있다. TAS도( (Fig.…”

“…FC=fractional crystallization; AFC=assimilation and fractional crystallization. (Chen et al, 2001;Fan et al, 2001Fan et al, , 2004Guo et al, 2001Guo et al, , 2004Guo et al, , 2013Qiu et al, 2002;Zhang et al, , 2004Zhang et al, , 2005Chen et al, , 2004Wang et al, 2003;Yang et al, 2004;Wang et al, 2005Wang et al, , 2008Yang et al, 2005aYang et al, , 2006Yang et al, , 2012aZhao et al, 2005Zhao et al, , 2007bLiu et al, 2006Liu et al, , 2008aLiu et al, , b, 2009Gao et al, 2008;Tang et al, 2008b;Guo et al, 2014;Ma et al, 2014a, b). 이는 위 암석들이 고-칼륨 칼크-알 칼리 내지는 쇼쇼나이트 계열에 속한다 (Fig.…”

“…OIB=oceanic island basalt (Sun and McDonough, 1989); N-MORB=normal mid-ocean ridge basalt (Sun and McDonough, 1989); LCC=average lower continental crust (Rudnick and Gao, 2005); UCC=average upper continental crust (Rudnick and Gao, 2005). Pb ratios for Early Cretaceous basaltic rocks from eastern China (Qiu et al, 2002;Xu et al, 2002;Zhang et al, , 2004Chen et al, 2004Chen et al, , 2008Yang et al, 2004Yang et al, , 2012bLiu et al, 2006Liu et al, , 2008aLiu et al, , b, 2009Huang et al, 2007;Zhao et al, 2007b;Wang et al, 2005Wang et al, , 2008Ma et al, 2014a, b). For comparison, Pb isotope data for basement rocks from the North China block, South China block I (represented by rocks from the middle-lower Yangtze valley and the regions south of it) and South China block II (represented by the Dabie-Sulu ultra-high pressure eclogites and gneisses, all calculated back to t = 130 Ma) from Yang et al (2012b), and Zeng and Yan (2014).…”

“…The boundary line dividing the alkaline and subalkaline series is from Irvine and Baragar (1971). Data sources for eastern China from Charoy and Raimbault (1994), Martin et al (1994), Lapierre et al (1997), Swell and Campbell (1997), Li and McCulloch (1998), Jahn et al (1999), Chen et al (2001Chen et al ( , 2004Chen et al ( , 2008, Fan et al (2001Fan et al ( , 2004, Guo et al (2001Guo et al ( , 2004Guo et al ( , 2005Guo et al ( , 2006Guo et al ( , 2013Guo et al ( , 2014, Xu et al (2002Xu et al ( , 2006, Zhang et al ( , 2004Zhang et al ( , 2005Zhang et al ( , 2010Zhang et al ( , 2012, , Wang et al (2003Wang et al ( , 2004Wang et al ( , 2005Wang et al ( , 2007Wang et al ( , 2008, Shu et al (2004), Yang et al (2004Yang et al ( , 2005aYang et al ( , 2006Yang et al ( , 2012aYang et al ( , b, 2013, Zhao et al (2005Zhao et al ( , 2007a, Huang et al (2006Huang et al ( , 2007, Liu et al (2006Liu et al ( , 2008aLiu et al ( , b, 2009…”

“…이는 위 암석들이 고-칼륨 칼크-알 칼리 내지는 쇼쇼나이트 계열에 속한다 (Fig. 2) Sr isotopic ratios for Early Cretaceous basaltic rocks from eastern China (Lapierre et al, 1997;Li and McCulloch, 1998;Jahn et al, 1999;Chen et al, 2001Chen et al, , 2004Chen et al, , 2008Fan et al, 2001Fan et al, , 2004Guo et al, 2001Guo et al, , 2004Guo et al, , 2005Guo et al, , 2013Guo et al, , 2014Xu et al, 2002;Zhang et al, , 2004Zhang et al, , 2012Wang et al, 2003Wang et al, , 2004Wang et al, , 2005Wang et al, , 2008Yang et al, 2004Yang et al, , 2005aYang et al, , 2006Yang et al, , 2012aLiu et al, 2006Liu et al, , 2008aLiu et al, , b, 2009Yu et al, 2006;Huang et al, 2007;Zhao et al, 2007b;Gao et al, 2008;Xie et al, 2008;Tang et al, 2009;Ma et al, 2014a, b). Data source for basaltic rocks from the Hayang Group in the Gyeongsang basin from Kwon et al (2013).…”