Advances in seismic imaging of crust and mantle ...

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(2014) as a tribute to this talented scientist who passed away at a relatively young age. ..... D., Badal, J., Klemperer, S., 2014. Zhongjie Zhang (1964–2013).
Tectonophysics 627 (2014) 1–3

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Preface

Advances in seismic imaging of crust and mantle: Preface

Deep seismic profiling aims to obtain the structure of crust and upper mantle using techniques such as seismic reflection, and seismic reflection/refraction as well as a series of broad-band seismic techniques including receiver functions and seismic tomography. Data are collected both on land and at sea, and in many cases across crystalline basement areas or basin–basement boundary zones. Over the years, deep seismic profiling has evolved both in methodology and understanding and has been integrated with other earth imaging techniques. Modern deep seismic transects provide clear images of the crust and mantle across various tectonic environments on the globe which constrain geodynamic evolution within key geological provenances. SEISMIX meetings (acronym for ‘International Symposium on Deep Structure of the Continents and their Margins’ symposium series) provide opportunity to gather seismic and other specialists from various continents to discuss and advance deep seismic profiling and understanding. These symposia were held once in two years since the first meeting in Cornell in 1984, and have led to important special issues including the recent one edited by Rawlinson and Goleby (2012). Seismix 2012, the 15th symposium of deep seismic profiling on Deep Structure of the Continents and their Margins, was held during September 16–20 in Beijing, China with a focus to present results from recent deep seismic case studies, seismic methodology advancements (active and passive techniques), and deep seismic surveys showing the structure of the crust and mantle. This special issue of Tectonophysics is an outcome from the Seismix 2012 in Beijing. However, sadly, Prof. Zhongjie Zhang of the Chinese Academy of Sciences who led the conference and who co-ordinated the proposal of this special issue of Tectonophysics is no more with us. He suddenly passed away last year and we dedicate this special issue in his memory. We open the special issue with an Obituary for Prof. Zhongjie Zhang, authored by Liu et al. (2014) as a tribute to this talented scientist who passed away at a relatively young age. Zhongjie was a pioneer in China for his work on seismic anisotropy and was widely known internationally for his contributions on deep seismic profiling to investigate the crustal and upper-mantle deformation, structures and evolution, particularly related to the Xizang–Qinghai (Tibet) Plateau and surrounding areas in western China. His outstanding publications helped elucidate the deformation of thinned lithosphere in northern China and provided new understanding of how Mesozoic disruption of the North China Craton occurred through underplating triggered lowercrustal flow of the Archean lithosphere. His significant contributions also provide insights into the evolution of the South China plate, crustal rheology and structure of the Tethyan Himalaya in southern Tibet, the geodynamics of East Tibet and the Sichuan Basin, among other topics. His sad demise was a great shock for his colleagues and collaborators worldwide and an irreparable loss for China's academic world.

http://dx.doi.org/10.1016/j.tecto.2014.06.001 0040-1951/© 2014 Elsevier B.V. All rights reserved.

We open the special issue with the contribution from Alcalde et al. (2014) who present a multidisciplinary approach from reflection seismic, well-log and regional data to formulate a 3D geological model for the Hontomín CO2 storage site in Spain. The geodynamic evolution of the study area is also inferred from the proposed model and this work offers a unique study of CO2 storage in a complex fractured carbonate reservoir. Lan et al. (2014) present the results from a reverse time migration from irregular surface, and their method eliminates limitations on surface irregularity, complexity of the subsurface structure and velocity function. The authors also investigate the influence of source types on the reverse time migration and through numerical examples, they demonstrate the feasibility and effectiveness of the new method. Kanao et al. (2014) investigate the crustal structure and tectonic evolution of the Enderby Land in East Antarctica through deep seismic surveys. Their study reveals lithospheric velocity and reflections of the Lützow–Holm Complex. A large graben structure is identified beneath the Amery Ice shelves. They also evaluate the tectonic evolution of Enderby Land by combining the coastal structure with that toward the inland plateau of the Gambursev Subglacial Mountains (GSM), which has important implications on the geological aspects related to the amalgamation and dispersal of the Gondwana supercontinent. Jia et al. (2014) present results from a long deep seismic sounding profile from the North China Craton in an attempt to elucidate the crustal structure and tectonics. Their results show that the Moho topography substantially varies in the central part of the craton and that the fault systems exert a major control on the evolution of this region. The authors also evaluate the convergence of the regional tectonic stress field since the Mesozoic, the modification of the lithospheric and crustal structure in eastern North China, and the controls of seismicity and metallogenesis. Yegorova and Pavlenkova (2014) present 2D density modeling of seismic profiles to decipher the structure of the upper mantle of Northern Eurasia. They employ velocity models on super-long seismic profiles with nuclear explosions and the density models obtained are interpreted in light of continental lithosphere evolution. They identify that the Archean depletion of the mantle is responsible for the gravity low of the Siberian Craton. Xu et al. (2014a) apply a successive three-point perturbation technique for tracing fast ray in complex 2D and 3D geological models. In their model, heterogeneous velocity distribution is identified in aggregates of arbitrarily shaped geological blocks. The authors combine segmentally iterative ray tracing (SIRT) and pseudo-bending methods to evaluate the block models. Empirical applications, including an example of the Bohemian Massif, are also presented. Lopez-Casado et al. (2014) present multifractal images of seismicity from the Ibero-Maghrebian region in the westernmost boundary between the Eurasian and African plates. The authors evaluate fractal dimensions of capacity, entropy, correlation and spectral slope. This

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Preface

region shows an uneven spatial distribution of seismic activity with areas of strong earthquakes. The authors correlate the lithospheric faults and the strong interaction between plate edges to the observed shallow and intermediate seismicity and the rupture of the plate boundary in the Betic–Rif–Alboran area. Xu et al. (2014b) analyze the crustal structure across the Kunlun fault from passive source seismic profiling in East Tibet. Combining with receiver function imaging and H-k stacking results the authors identify a crustal thickness of 64 km under Songpan–Ganzi, and 56–62 km under Qaidam–Kunlun and Qilian. Their study illustrates crust flow mechanism operating more strongly in the western region along the Kunlun fault. Teng et al. (2014) investigate the Moho depth, seismicity and seismogenic structure of mainland China based on wide-angle seismic profiles. Their results demonstrate that the average Moho depth is about 35 km in Southeast China, 38 km in North and Northeast China, 51 km in Northwest China and 65 km in Tibet. Based on the link between the seismic velocity structure and the seismogenic layer of the crust that concentrates 80% of the released seismic energy, the authors discriminate the places with greater or lesser capacity to generate seismic energy. South China and Northwest China show a distinct earthquake generating capacity when compared to that of Tibet. Chen et al. (2014) formulate a thermo-rheological model along a seismic profile in eastern Tibet. Their study identifies a hightemperature anomaly within the uppermost mantle of eastern Tibet. They also pick out significant lateral variations in rheological strength along the profile. By combining these results with the observed crustal/ lithospheric architecture, Pn velocity distribution and magmatism in the eastern Tibetan margin, the authors suggest that the delamination of a thickened lithospheric mantle root beneath eastern Tibet is responsible for the growth of the eastern Tibetan margin. Zhao et al. (2014) apply shear wave splitting measurements to investigate the upper mantle deformation beneath central-southern Tibet. The transition in shear wave splitting at 30.5°N is correlated with distinct upper mantle deformation from south to north. The marked anisotropy in the north is considered to result from the eastward flow between the advancing Indian plate to the south and Eurasian plate to the north. Hong (2014) evaluate the influence of complex structures in continental margin on the regional seismic wavefield. The study focuses on the continental margin around the Korean Peninsula where regional waves are seen to attenuate while passing across the continental margin. The growth rate within the continent is stronger than inherent attenuation rate, causing seismic amplification. The author identifies a directional partition of seismic energy by crustal structures in the paths. Deng et al. (2014) present a 3D density structure of South China from integrated seismic velocity and gravity data. The density models identify the Chenzhou–Linwu fault as the southern termination of the boundary between the Yangtze and Cathaysia blocks. Crustal composition and temperature distribution are employed to formulate different laws with linear relationships between seismic velocity and density, and these allow distinguishing the various tectonic units in South China. He et al. (2014) provide evidence for plume-induced rifting in the Songliao Basin of Northeast China from seismic data. A deepening of the 410 and 660 km discontinuities beneath the Songliao Basin is identified. The seismic evidence shows the presence of a mantle plume, underplating and rifting process in NE China. A projection of the proposed plume onto the surface overlaps with the locations of the lithosphere and crustal thinning as well as the mafic–ultramafic domains. The authors thus propose an upwelling mantle plume and related extension as the main trigger for the formation of the Mesozoic Songliao Basin in NE China. Kim et al. (2014) deal with hypocentral parameter inversion for regions with poorly known velocity structures, a crucial factor in seismic monitoring. The authors introduce an iterative velocity updating scheme that can be combined with conventional hypocentral inversion methods. The feasibility and accuracy of the algorithm are tested with synthetic and field data. The proposed scheme can be implemented in any conventional method that is based on a fixed velocity model.

Lu et al. (2014) present a 2.5 dimensional tomography model for the uppermost mantle beneath the Sichuan–Yunnan region and surrounding areas based on Pn and Sn travel time data with long and short epicentral distance ranges. Their study provides further evidence for the subduction of Indian plate beneath Myanmar–Yunnan region. The authors identify the presence of hot upwelling beneath the Hainan region and conclude that the heat flow from the upper mantle beneath Yunnan has complex features. We thank the following referees for sparing their valuable time and efforts in reviewing the papers submitted to this special issue.

Abdul Bhatti Alexey Goncharov Alexey Shulgin Alireza Malehmir An Yin Antonio Casas Aubreya Adams Beatriz Benjumea Bihong Fu Bin Shan Brian Kennett Chuansong He Daniel Stich Dapeng Zhao David Snyder Don L. Anderson Edoardo Del Pezzo Eiichi Fukuyama Eleni Kokinou Francisco Luzon Fred J. Davey G. Keller Giorgio Ranalli Gou Fujie J. Kim Welford Jacek Stankiewicz James Ni Jean-Claude Mareschal Jiafu Hu Jianshe Lei Jingyi Chen Joachim Ritter Jose Badal Kaijian Liu Kwang-Hyun Cho Luis Pujades Luis Pujades Marcelo Rocha Marek Jarosinski Masaki Kanao Mikhail K. Kaban Minghui Zhao Nicholas Rawlinson Pin Yan Piotr Sroda Rainer Kind Ramon Carbonell Rizheng He Rongfeng Ge Stefano Tavani Sung-Joon Chang Susana Custodio Tae-Kyung Hong Thomas Daley Tom Hearn Walter Mooney Weisen Shen Wolfgang Rabbel Xi Zhang Yasuyuki Kano Yuri Rebetsky Zhaohui Yang Zhi Guo Zhouchuan Huang Zoltan Hajnal

Preface

We thank all the authors who contributed to this special issue. We also express our sincere thanks to Prof. Hans Thybo, Editor-in-Chief of Tectonophysics for encouragement and overall guidance in bringing out this special issue. We hope that the seventeen contributions assembled in this volume would evoke wide interest among the related geoscience community. References Alcalde, J., Marzan, I., Saura, E., Marti, D., Ayarza, P., Juhlin, C., Perez-Estaun, A., Carbonell, R., 2014. 3D geological characterization of the Hontomín CO2 storage site, Spain: multidisciplinary approach from seismic, well-log and regional data. Tectonophysics 627, 6–25. Chen, L., Berntsson, F., Zhang, Z., Wang, P., Wu, J., Xu, T., 2014. Seismically constrained thermo-rheological structure of the eastern Tibetan margin: implication for lithospheric delamination. Tectonophysics 627, 122–134. Deng, Y., Zhang, Z., Badal, J., Fan, W., 2014. 3-D density structure under South China constrained by seismic velocity and gravity data. Tectonophysics 627, 159–170. He, C., Dong, W., Chen, X., Santosh, M., Niu, S., 2014. Seismic evidence for plume-induced rifting in the Songliao Basin of Northeast China. Tectonophysics 627, 171–181. Hong, T.K., 2014. Influence of continental margin on regional seismic wavefield. Tectonophysics 627, 141–158. Jia, S., Wang, F., Tian, X., Duan, Y., Zhang, J., Liu, B., Lin, J., 2014. Crustal structure and tectonic study of North China Craton from a long deep seismic sounding profile. Tectonophysics 627, 48–56. Kanao, M., Suvorov, V.D., Yamashita, M., Mishenkin, B., 2014. Crustal structure and tectonic evolution of Enderby Land, East Antarctica, as revealed by deep seismic surveys. Tectonophysics 627, 38–47. Kim, W., Hong, T.K., Kang, T.S., 2014. Hypocentral parameter inversion for regions with poorly known velocity structures. Tectonophysics 627, 182–192. Lan, H., Zhang, Z., Chen, J., Liu, Y., 2014. Reverse time migration from irregular surface by flattening surface topography. Tectonophysics 627, 26–37. Liu, E., Chen, Y., Yang, D., Badal, J., Klemperer, S., 2014. Zhongjie Zhang (1964–2013). Tectonophysics 627, 4–5. Lopez-Casado, C., Henares, J., Badal, J., Pelaez, J.A., 2014. Multifractal images of the seismicity in the Ibero-Maghrebian region (westernmost boundary between the Eurasian and African plates). Tectonophysics 627, 82–97. Lu, Y., Zhang, Z., Pei, S., Sandvol, E., Xu, T., Liang, X., 2014. 2.5-dimensional tomography of uppermost mantle beneath Sichuan–Yunnan and surrounding regions. Tectonophysics 627, 193–204. Rawlinson, N., Goleby, B.R., 2012. Imaging of continents and their margins: new research at the confluence of active and passive seismology. Tectonophysics 572–573, 1–6.

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Teng, J., Deng, Y., Badal, J., Zhang, Y., 2014. Moho depth, seismicity and seismogenic structure in China mainland. Tectonophysics 627, 108–121. Xu, T., Li, F., Wu, Z., Wu, C., Gao, E., Zhou, B., Zhang, Z., Xu, G., 2014a. A successive threepoint perturbation method for fast ray tracing in complex 2D and 3D geological models. Tectonophysics 627, 72–81. Xu, T., Wu, Z., Zhang, Z., Tian, X., Deng, Y., Wu, C., Teng, J., 2014b. Crustal structure across the Kunlun fault from passive source seismic profiling in East Tibet. Tectonophysics 627, 98–107. Yegorova, T., Pavlenkova, G., 2014. Structure of the upper mantle of Northern Eurasia from 2D density modeling on seismic profiles with peaceful nuclear explosions. Tectonophysics 627, 57–71. Zhao, J., Murodov, D., Huang, Y., Sun, Y., Pei, S., Liu, H., Zhang, H., Fu, Y., Wang, W., Cheng, H., Tang, W., 2014. Upper mantle deformation beneath central-southern Tibet revealed by shear wave splitting measurements. Tectonophysics 627, 135–140.

M. Santosh School of Earth Science and Resources, China University of Geosciences Beijing, 29 Xueyuan Road, Haidian district, Beijing 100083, China Corresponding author. Tel./fax: +86 10 82323117. E-mail addresses: [email protected], [email protected]. Ramon Carbonell1 CSIC-Spanish National Research Council, Barcelona, Spain E-mail address: [email protected]. Irina Artemieva2 IGG, University of Copenhagen, Oester Voldgade 10, Copenhagen 1350, Denmark E-mail address: [email protected]. José Badal3 Physics of the Earth, University of Zaragoza (Sciences B), Pedro Cerbuna, 12, 50009 Zaragoza, Spain E-mail address: [email protected].

1 Tel.: + 34 93 409 5410x252 (switchboard), + 34 93 409 5419 (direct), + 34 660 572489 (mobile); fax: +34 93 411 0012. 2 Tel.: +45 72569080/50882438. 3 Tel.: +34 976 761139.