Stratigraphic Records of the Dynamic Uplift of the Emeishan Large Igneous Province
Total Page：16
File Type：pdf, Size：1020Kb
International Geology Review ISSN: 0020-6814 (Print) 1938-2839 (Online) Journal homepage: http://www.tandfonline.com/loi/tigr20 Stratigraphic records of the dynamic uplift of the Emeishan large igneous province Peng Wu, Shaofeng Liu, Binghui He & Guoxing Dou To cite this article: Peng Wu, Shaofeng Liu, Binghui He & Guoxing Dou (2016) Stratigraphic records of the dynamic uplift of the Emeishan large igneous province, International Geology Review, 58:1, 112-130, DOI: 10.1080/00206814.2015.1065515 To link to this article: http://dx.doi.org/10.1080/00206814.2015.1065515 View supplementary material Published online: 20 Jul 2015. Submit your article to this journal Article views: 98 View related articles View Crossmark data Full Terms & Conditions of access and use can be found at http://www.tandfonline.com/action/journalInformation?journalCode=tigr20 Download by: [Universiti Putra Malaysia] Date: 28 October 2015, At: 00:39 INTERNATIONAL GEOLOGY REVIEW, 2016 VOL. 58, NO. 1, 112–130 http://dx.doi.org/10.1080/00206814.2015.1065515 Stratigraphic records of the dynamic uplift of the Emeishan large igneous province Peng Wua,b, Shaofeng Liua,b, Binghui Hea,b and Guoxing Douc aState Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Beijing, China; bSchool of Earth Science and Resources, China University of Geosciences (Beijing), Beijing, China; cResearch Institute of Coal Geophysical Exploration of China National Administration of Coal Geology, Zhuozhou, China ABSTRACT ARTICLE HISTORY Fluid dynamical and numerical modelling predicts a large-scale regional domal uplift prior to Received 25 April 2015 basalt eruptions in large igneous provinces, which can be readily measured when a plume head Accepted 21 June 2015 rises below a shallow marine sedimentary basin. Research on the sedimentology, biostratigraphy, KEYWORDS and isotopic chronology of the Emeishan large igneous province demonstrates that the sedimen- Emeishan large igneous tary environment in the Maokou stage is not uniform carbonate platform facies, but rather province; Maokou limestone; sedimentary facies with a north–south linear alignment and west–east different distribution syn-depositional fault; controlled by the syn-depositional normal faulting of the Changhai and Xiaojiang faults, which dynamic topography are the result of underwater dynamic uplift induced by deep mantle activity. The dynamic uplift started in the Maokou stage. Thus, thinning of the Maokou limestone was the product of the difference in the initial depositional thickness caused by the underwater uplift and post-deposi- tional surface uplift and erosion, but post-depositional uplift was much less than kilometre scale. Sedimentary facies differentiation and tectonic–sedimentary evolution in the Maokou stage provide a constraint for the time of the initial eruption and eruption environment before and during the Emeishan basalt eruption. Small-scale magmatic activity might have already begun in the middle of the Maokou stage, whereas submarine and terrestrial sedimentary environments coexisted before and during Emeishan basalt eruption. 1. Introduction doming by an ascending mantle plume. Their evidence also included palaeo-karsts on the top of the Maokou The Emeishan large igneous province (Emeishan LIP) in Formation (He et al. 2004, 2010) and alluvial fan con- southwestern China has attracted a large number of glomerates along the eastern and northeastern sides of studies, especially over the last 20 years (Chung et al. the Emeishan LIP (He et al. 2006a, 2006b). Their model 1998; Courtillot et al. 1999;Heet al. 2003a;Xuet al. indicated the totally subaerial environment of the basalt 2004, 2014; Ali et al. 2010; Zhong et al. 2011), because eruptions. However, many scholars have raised doubts this province may be closely associated with middle regarding He et al.’s(2003a) model. The most represen- Permian mass extinction (Ali et al. 2002; Wignall et al. Downloaded by [Universiti Putra Malaysia] at 00:39 28 October 2015 tative research was performed by Peate and Bryan 2009a, 2009b; Bond et al. 2010; Cao et al. 2013). (2008, 2009), who reinvestigated the Daqiao section at Nevertheless, there remains considerable controversy the edge of the strongly eroded ‘inner zone’ and recog- regarding the dynamic mechanisms that formed the nized voluminous mafic hydromagmatic deposits that Emeishan LIP and the environment before, during, and were previously interpreted as alluvial fan sediments after Emeishan volcanism (Chung and Jahn 1995; shed from a pre-volcanic domal high. Their results Thompson et al. 2001; Song et al. 2004; Zhang and clearly demonstrated that both subaerial and submarine Dong 2007; Xiao et al. 2008; Leng and Zhong 2010), environments coexisted prior to and during the initial mainly in regard to the following viewpoints. He et al. Emeishan basalt eruptions. Sun et al.(2010) also con- (2003a, 2003b, 2005, 2009) proposed a kilometre-scale firmed that many regions experienced rapid subsidence doming uplift and differential erosion model based on and were deep-water facies prior to the Emeishan basalt the biostratigraphic correlation of the Maokou eruptions, based on conodont age of the uppermost Formation immediately underneath the Emeishan beds of the Maokou Formation. Wang et al.(2014), basalts, which resulted from thermal or dynamic based on tectonic restoration and reinterpretation of CONTACT Shaofeng liu [email protected] © 2015 Taylor & Francis INTERNATIONAL GEOLOGY REVIEW 113 lithofacies sequences to the Binchuan section and et al. 2003a). There are many main fault belts, which Daqiao section, suggested a linear alignment of the include, from west to east, the NS-striking Jinghe– marine, submarine, and subaerial eruption environment Changhai fault (hereafter referred to as the Changhai from west to east before and during the Emeishan fault), the Mopanshan–Lvzhijiang fault (hereafter basalt eruptions. referred to as the Lvzhijiang fault), the Anninghe– Previous research focused primarily on the crustal Yimen fault (hereafter referred to as the Anninghe processes and environment after the deposition of the fault), the Ganluo–Xiaojiang fault (hereafter referred Maokou Formation and before or during the basalt erup- to as the Xiaojiang fault), and the NW-striking tions in the Emeishan LIP, but little research has been Xichang–Qiaojia fault (hereafter referred to as the conducted on the syn-depositional tectonic activity and Qiaojia fault) (Figure 1). The Chenghai, Lvzhijiang, sedimentary processes during the Maokou stage. He Anninghe, and Xiaojiang faults all have lengths of et al.(2003b, 2006a) and Li et al.(2011) briefly described several hundred kilometres, cut deep into the litho- the sedimentary environment of the Maokou Formation sphere, and control the structural evolution in the in the Emeishan LIP as a shallow marine carbonate plat- research area (Zhang et al. 1988). For convenience, form with a stable crust, uniform tectonic setting, and three sub-provinces were distinguished to describe horizontal depositional surface without intense fault the Emeishan LIP, namely the Western, Central, and activity. Peate and Bryan (2008) and Wang et al.(2014) Eastern regions based on the Chenghai and Xiaojiang referred to the possibility of differential uplift/normal faults. The Central Region overlying the ‘Panxi palaeor- faulting of the Permian Maokou limestone. Thus, were ift zone’ (Tan 1987;Heet al. 2003a) refers to the area all the research areas shallow marine carbonate platform between the Changhai and Xiaojiang faults, the facies? Were there differences in the sedimentary thick- Western Region refers to the area on the western ness, terrain, and differentiation in sedimentary facies? side of the Chenghai fault, and the Eastern Region Did pre-existing fault activity occur and control the sedi- refers to the area on the eastern side of the mentation processes during and after the deposition of Xiaojiang fault. the Maokou Formation? If so, was this fault activity The thickness and components of the Emeishan related to deep mantle activity? basalts change regularly from west to east (Xu et al. The classic mantle plume model developed by 2004). In terms of thickness, the basalt series gradually Campbell and Griffiths (1990)consideredregional becomes thinner, from over 5000 m in the west to a few domal uplift prior to basalt eruptions, which are read- hundred metres in the east. The thickest belts and ily measured, especially when a plume head rises mutation belts are consistent with the north–south below a shallow marine sedimentary basin (Griffiths Changhai and Xiaojiang faults (Zhang et al. 1988). In and Campbell 1991; Campbell 2007) with continuous regard to components, thick sequences of low-Ti volca- sediments of equal thickness. Therefore, research on nic rocks are mainly distributed in the Western Region, the tectonic activity and sedimentary environment in with some sections having subordinate high-Ti lavas at the Maokou stage can verify the potential of the the top as represented by the Binchuan and Pingchuan doming uplift model for the Emeishan LIP and the sections; picrites and low-Ti, high-Ti, and alkaline lavas accuracy of the estimated level of uplift and further coexist in the Central Region; and thin sequences of Downloaded by [Universiti Putra Malaysia] at 00:39 28 October 2015 reveal the dynamic topography during and after the high-Ti volcanic rocks mainly occur in the Eastern Maokou stage (i.e. surface topography induced by Region