Rapid lithospheric thinning of the North China Craton: New evidence from cretaceous mafic dikes in the Jiaodong Peninsula

Abstract

The North China Craton is a classic case for the destruction of an ancient craton, in that it records the loss of more than 100 km of ancient refractory lithospheric mantle during the late Mesozoic and early Cenozoic. However, the mechanisms for this lithospheric thinning remain controversial in large part due to the lack of any systematic investigations of the Mesozoic asthenospheric mantle via its derived mafic rocks, which are key to understand the thinning processes. In this paper, we present detailed zircon U-Pb geochronology, elemental geochemistry, and Sr-Nd-Hf isotopic data for lamprophyres and diabase-porphyries of the Jiaodong Peninsula, in the eastern North China Craton in order to place constraints on models for lithospheric thinning. Our results show that the lamprophyres and diabase-porphyries are derived from the convective asthenospheric mantle via different degrees of partial melting, and that this mantle source was previously modified by carbonatitic liquids. Zircon LA-ICP-MS U-Pb dating suggests an emplacement age for these rocks of 123-121 Ma, the earliest evidence for asthenospherically-derived melts in the Jiaodong Peninsula so far. This emplacement age indicates that the thickness of the lithosphere in the Jiaodong Peninsula was relatively thin at that time. Co-occurrence of the asthenospheric and lithospheric mantle-derived mafic rocks as well as high-Mg adakites record a rapid transition from lithospheric to asthenospheric mantle sources, indicating that the lithosphere beneath the Jiaodong Peninsula was rapidly detached just prior to ca. 120 Ma. Lithospheric thinning of the North China Craton may have been initiated from the Jiaodong Peninsula and Bohai Sea and then propagated towards the interior of the craton.

Petrogenesis of Early Cretaceous intermediate-felsic dikes in the Jiaodong Peninsula, south-eastern North China Craton: Constraints from geochronology, geochemistry and Sr-Nd-Pb-Hf isotopes

“…123-121 Ma) (Ma et al, 2014(Ma et al, , 2016. Those intermediate-felsic dikes studied here are mainly oriented to the N, the NNE, and the NNW in the Jiaobei terrain and to the E, the NE, and the NEE in the Sulu orogenic belt (Fig.…”

“…Mesozoic intrusions in the Jiaodong Peninsula can be divided into four suites: (1) the Late Triassic syenite, such as Jiazishan intrusion, which is only found in the easternmost Jiaodong Peninsula (215-209 Ma, LA-ICP-MS zircon U-Pb age, Chen et al, 2003); 2 (Fig. 1b) (Tan et al, 2008;Liu et al, 2009;Cai et al, 2013, A C C E P T E D M A N U S C R I P T 8 2015; Ma et al, 2014Ma et al, , 2016Deng et al, 2017;Liang et al, 2017). Two types of mafic dike have been identified, those derived from enriched lithospheric mantle (arc-like type with enrichment in LILE and LREE but depletion in HFSE; 130-110 Ma) (Liu et al, 2009;Cai et al, 2013Cai et al, , 2015Ma et al, 2014;Deng et al, 2017;Liang et al, 2017) and those derived from asthenospheric mantle (OIB-like type with no depletion in HFSE and enrichment in LREE;…”

“…into Jiaodong Peninsula were proved to be derived from asthenospheric mantle (Ma et al, 2014(Ma et al, , 2016, which means that the thickness of the lithosphere is no greater than 80 km at this period (Ma et al, 2014). However, in the Early Cretaceous, the dynamic processes and mechanism leading to the lithospheric thinning as well as magmatism at Jiaodong still remain debated, and those causes mainly include foundering of the lower crust (Gao et al, 2004(Gao et al, , 2008Liu et al, 2009), lithospheric delamination (Wu et al, 2005), and thermo-mechanical erosion resulted by asthosphere mantle convection (Xu et al, 2014) or caused by rollback of Paleo-Pacific slab (Deng et al, 2017).…”

“…Widespread Early Cretaceous mafic-intermediate-felsic dikes at Jiaodong offer a ideal opportunity to probe the deep tectonic evolution and its driving forces (Deng et al, 2017). However, previous studies in the Jiaodong Peninsula mainly focused on the Early Cretaceous mafic dikes for revealing the nature of mantle (Liu et al, 2009;Guo et al, 2014;Ma et al, 2014Ma et al, , 2016Cai et al, 2015;Deng et al, 2017;Liang et al, 2017), and only a few researches referred to the intermediate-felsic dikes (Tan et al, 2007(Tan et al, , 2008Cai et al, 2013Cai et al, , 2015. The intermediate-felsic dikes could also provide significant…”

The Early Cretaceous sedimentary‐tectonic attributes of Lingshan Island Basin, East Shandong Province, China: Constraints from the chemical compositions of detrital heavy minerals

“…Liang et al () studied four Early Cretaceous mafic dikes aged at ~126 Ma in south‐eastern Jiaolai Basin and found that those mafic dikes resemble the ARC‐like dikes in Jiaodong Peninsula (Cai et al, ; Guo, Fan, Wang, & Zhang, ; Liu et al, ; Tan et al, ). OIB‐like mafic rocks were locally found in north‐west Jiaodong Peninsula (L. Ma et al, ; L. Ma et al, ). As for the peridotite rocks, there are plenty of mafic‐ultramafic rock lenses in Sulu orogenic belt, including Qianliyan Uplift (S. Chen, Yang, & Li, ; S. Z. Chen et al, ; Ying, Zhang, Kita, Morishita, & Shimoda, ; R. Y. Zhang & Liou, ; J. P. Zheng et al, ), which might provide peridotite spinel grains for Laiyang Group in Lingshan Island.…”