GEOLOGICAL JOURNAL Geol. J. 50:93–103 (2015) Published online 10 October 2013 in Wiley Online Library (wileyonlinelibrary.com). DOI: 10.1002/gj.2530 Destruction of the North China Craton: a perspective based on receiver function analysis CHUANSONG HE 1*, SHUWEN DONG 2, M. SANTOSH 3, QIUSHENG LI 2 and XUANHUA CHEN 2 1Institute of Geophysics, China Earthquake Administration, Beijing, China 2Chinese Academy of Geological Science, Beijing, China 3School of Earth Sciences and Resources, China University of Geosciences, Beijing, China The North China Craton (NCC), which is composed of the eastern NCC and the western NCC sutured by the Palaeoproterozoic Trans-North China Orogen, is one of the oldest continental nuclei in the world and the largest cratonic block in China. The eastern NCC is widely known for its significant lithospheric thinning and destruction during the Late Mesozoic. Models on the destruction of the eastern NCC can be prin- cipally grouped into two: (1) thermal/mechanical and/or chemical erosion, and (2) lower crustal and (or) lithospheric delamination. The ero- sion model suggests that the NCC lithospheric thinning resulted from chemical and/or mechanical interactions of lithospheric mantle with melts or hydrous fluids derived from the asthenosphere, whereas the delamination model proposes lithospheric destruction through foundering of eclogitic lower crust together with lithospheric mantle into the underlying convecting mantle. However, those models lack seismic evidence to explain the destruction process. Here, we analyse the crustal structure and upper mantle discontinuity by employing the H–k stacking tech- nique of receiver function as well as the depth domain receiver function. Our results indicate deep mantle upwelling and lower crustal delam- ination beneath the eastern NCC, and suggest that either or both of these processes contributed to the unique lithospheric thinning and destruction of the eastern NCC. © 2013 The Authors. Geological Journal published by John Wiley & Sons, Ltd. Received 25 April 2013; accepted 1 September 2013 KEY WORDS receiver function; crustal structure; upper mantle discontinuity; upwelling mantle plume; lower crustal and lithospheric delamination; North China Craton 1. INTRODUCTION China Orogen (central NCC) (Zhao et al., 2001, 2005, 2012; Zhai and Santosh, 2011; Zhao and Zhai, 2013; Zheng The North China Craton (NCC) refers to the Chinese part of the et al., 2013). The eastern NCC has undergone significant Sino-Korean Platform, comprising a triangular region covering tectonothermal reactivation and destruction with a dramatic approximately 1 500 000 km2, and bound by faults and younger change in lithospheric architecture during the Ordovician to orogenic belts. The Early Palaeozoic Qilianshan Orogen and the Cenozoic (Chen, 2010). Recent evidence gathered from the Late Palaeozoic–Late Mesozoic Central Asian Orogenic geological and geophysical studies confirm that the Eastern Belt bound the craton to the west and the north, respectively Block of the NCC has lost a considerable part of its litho- (Ren et al., 1987; Zorin et al., 2001; Zhao et al., 2001; Xiao spheric keel (Zhang, 1993, 2007; Cope and Graham, 2007; et al., 2013). To the south, the craton is bordered by the Li et al., 2007; Gao et al., 2008; Wu et al., 2008; Xu and Qinling–Dabie–Sulu ultrahigh-pressure metamorphic belt that Zhao, 2009; Zheng et al., 2009; Chen, 2009; Santosh, 2010). separates the NCC from the Yangtze Craton (Yang et al., Models on the destruction of the eastern NCC can be prin- 2003; Wu and Zheng, 2013; Santosh and Somerville, 2013). cipally grouped into two: (1) thermal/mechanical and/or The NCC is composed of two major Precambrian chemical erosion (e.g. Menzies et al., 1993; Deng et al., blocks, the eastern and western NCC, sutured along a 1994; Zheng et al., 1998); and (2) lower crustal and (or) lith- Palaeoproterozoic collision zone known as the Trans-North ospheric delamination (Deng et al., 1994; Gao et al., 1998; Xu et al., 2002; Ling et al., 2009). The erosion model suggests that the thinning of the NCC lithosphere resulted *Correspondence to: C. He, Institute of Geophysics, China Earthquake from chemical and/or mechanical interactions of lithospheric Administration, Beijing, China. E-mail: [email protected] mantle with melts or hydrous fluids derived from the © 2013 The Authors. Geological Journal published by John Wiley & Sons, Ltd. This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited. 94 C. HE ET AL. asthenosphere. The delamination model proposes that the dynamics implications. Based on the results, we suggest an in- destruction of the lithosphere was caused by foundering of tegrated model for the cratonic destruction of the eastern NCC. eclogitic lower crust together with lithospheric mantle into the underlying convecting mantle (Ling et al., 2009). How- ever, the processes of erosion and delamination remain contro- versial and lack robust evidence from seismic investigation. 2. METHODS AND DATA The depth domain receiver function can effectively delin- eate the 410 and 660 km interfaces, and 410 and 660 km dis- This study performs a careful analysis of the receiver func- continuity topography displays the thermal state of the upper tions in the NCC, in order to characterize the bulk seismic mantle from which any upwelling mantle plume from the properties of the crust with local estimates for the crustal lower mantle can be tracked (e.g. Chen and Ai, 2009; Huerta thickness and Vp/Vs ratio (Zandt and Ammon, 1995; Zhu et al., 2009; He, 2010). The H–k stacking technique can be and Kanamori, 2000). For this purpose, we apply the stack- used to derive the thickness and the average composition ing procedure of Zhu and Kanamori (2000) to 314 seismic of the continental crust, which in turn is used to estimate stations located in the NCC (Fig. 1). These stations have the composition of the lower crust and its geodynamic impli- been in operation from July 2008 to the present-day by the cations (Zandt and Ammon, 1995, Christensen, 1996; Niu China Earthquake network (Zheng et al., 2010). We selected and James, 2002; Nair et al., 2006; Thompson et al., 2010; a total of 441 events with magnitude mb ≥ 5.8 recorded by He et al., 2013a, 2013b). In this study, we analyse the crustal those stations (Figs. 1 and 2 and Supplementary Table S1). and upper mantle structure by employing the H–k stacking For each event–station pair, data were selected within the technique (Zhu and Kanamori, 2000) and depth domain ranges of 30–95° with reasonable back azimuth coverage and receiver function (Yuan et al., 1997), and address their initially windowed 15 s before and 120 s after the P-wave pick. Figure 1. Distribution of seismic stations and the general tectonic framework in North China. Western Block: Western NCC, Trans-North China Orogen: cen- tral NCC, Eastern Block: eastern NCC, pink triangle: seismic station, yellow circle: city. Inset figure: the study region within the North China Craton (marked by box), SLB (Songliao Basin), WBL (Western Block), EBL (Eastern Block), TNCO (Trans-North China Orogen), Q-DOB (Qinling–Dabie Orogen Belt), YZB (Yangtze Block), CSB (Cathaysia Block), JGB (Junggar Basin), TSFS (Tianshan Fold System), TRB (Tarim Basin), QDB (Qaidam Basin), SPGB (Songpan–Ganzi Block), QTB (Qiangtang Block). This figure is available in colour online at wileyonlinelibrary.com/journal/gj © 2013 The Authors. Geological Journal published by John Wiley & Sons, Ltd. Geol. J. 50:93–103 (2015) DOI: 10.1002/gj CRATON DESTRUCTION: A PERSPECTIVE FROM NORTH CHINA 95 Figure 2. Distribution of selected events. For each event–station pair, data were selected within the distance ranges of 30–95° with reasonable back azimuth coverage. This figure is available in colour online at wileyonlinelibrary.com/journal/gj Data are filtered using a zero-phase Butterworth bandpass filter Based on it, we converted the time domain receiver with corner frequencies of 0.03–3 Hz (or 0.05–1 Hz for upper functions into the depth domain after corrections for the mantle discontinuity study). We then used a modified incidence angle effect (correcting the move out of Ps frequency domain deconvolution (Langston, 1979; Owens conversions to the same incidence or near vertical et al., 1984; Zhu and Kanamori, 2000), and the Gaussian incidence) (Yuan et al., 1997). By stacking all depth factor and water level were set to 3 and 0.01 (or 1 and 0.01 domain receiver functions from different back azimuths for upper mantle discontinuity study), respectively. at each station respectively, we obtain the average The stacking is usually done in the time domain for a receiver function at each station (Owens et al., cluster of events (Owens et al., 1984; Zhu and Kanamori, 1984). The average receiver function can clearly de- 2000). Here we chose unequal weights (0.6, 0.3 and 0.1) lineate the upper mantle discontinuity (Zhu, 2000) for Ps, PpPs and PpSs + PsPs phases of the Moho, (Supplementary Fig. S2). respectively. Using the Taylor expansion at the maximum and omitting the higher-order terms to quantitatively estimate the uncertainty (Zhu and Kanamori, 2000) of our results, we measured error bars for h and κ,which 3. CRUSTAL THICKNESS AND Vp/Vs RATIO line up with longitude, by taking into account uncertainties (Fig. 3). We also show two examples of The crustal thickness of the NCC identified by this study H–k stacking computed at two stations located at the shows a gradual increase in a northwestward direction from NCC (Supplementary Fig. S1). 32 to 48 km (Fig. 3a, Fig. 4, arrow a) and in a Generally, each amplitude on the radial receiver westward direction in the western part (outside the NCC) function is produced by a primary P-to-S conversion at (Fig.