LI Guo-Hui,
SUI Yi,
ZHOU Yuan-Ze
.2014.Low-velocity layer atop the mantle transition zone in the lower Yangtze Craton from P waveform triplication.Chinese Journal Of Geophysics,57(7): 2362-2371,doi: 10.6038/cjg20140730
Low-velocity layer atop the mantle transition zone in the lower Yangtze Craton from P waveform triplication
LI Guo-Hui1,2, SUI Yi1,2, ZHOU Yuan-Ze1,2
1. Key Laboratory of Computational Geodynamics, Chinese Academy of Sciences, Beijing 100049, China; 2. College of Earth Sciences, University of Chinese Academy of Sciences, Beijing 100049, China
Abstract：The P waveform triplications from the seismograms of a mid-deep earthquake at the Ryukyu subduction zone recorded by the Chinese Digital Seismic Network between the epicentral distances from 10° to 23° are used to study the upper mantle structure beneath the lower Yangtze craton. Comparing the observed seismograms with the synthetic ones from different models based on IASP91 earth model and using the ray-tracing method, we find that the 410 km discontinuity is a gradient zone with the thickness of 20 km and there is a low-velocity layer atop the discontinuity which becomes thicker from southwest to northeast beneath the lower Yangtze craton. The low-velocity layer is characterized by a thickness varied from 40 km to 57 km and P velocity decreased by 2.7%~4.5% and should be the result of partial melting of mantle peridotite.
Bagley B, Courtier A, Revenaugh J. 2009. Melting in the deep upper mantle oceanward of the Honshu slab. Phys. Earth Planet. Inter., 175(3-4): 137-144. Bercovici D, Karato S I. 2003. Whole-mantle convection and the transition-zone water filter. Nature, 425(6953): 39-44. Chambers K, Woodhouse J H, Deuss A. 2005. Topography of the 410 km discontinuity from PP and SS precursors. Earth Planet. Sci. Lett., 235(3-4): 610-622. Chevrot S, Vinnik L, Montagner J P. 1999. Global-scale analysis of the mantle Pds phases. J. Geophys. Res., 104(B9): 20203-20219. Chu R S, Schmandt B, Helmberger D V. 2012. Upper mantle P velocity structure beneath the Midwestern United States derived from triplicated waveforms. Geochem. Geophy. Geosy., 13(2), doi:10.1029/2011GC003818. Collier J D, Helffrich G R, Wood B J. 2001. Seismic discontinuities and subduction zones. Phys. Earth Planet. Inter., 127(1-4): 35-49. Courtier A M, Revenaugh J. 2007. Deep upper-mantle melting beneath the Tasman and Coral Seas detected with multiple ScS reverberations. Earth Planet. Sci. Lett., 259(1-2): 66-76. Deon F, Koch-Muller M, Rhede D, et al. 2011. Water and iron effect on the P-T-x coordinates of the 410 km discontinuity in the Earth upper mantle. Contrib. Mineral. Petrol., 161(4): 653-666. Deuss A. 2007. Seismic observations of transition-zone discontinuities beneath hotspot locations.//Plates, Plumes and Planetary Processes. GSA Spec. Pap., 430: 121-136. Dziewonski A M, Anderson D L. 1981. Preliminary reference Earth model. Phys. Earth Planet. Inter., 25(4): 297-356. Eagar K C, Fouch M J, James D E. 2010. Receiver function imaging of upper mantle complexity beneath the Pacific Northwest, United States. Earth Planet. Sci. Lett., 297(1-2): 141-153. Fee D, Dueker K. 2004. Mantle transition zone topography and structure beneath the Yellowstone hotspot. Geophys. Res. Lett., 31(18), L18603: doi:10.1029/2004GL020636. Gao W, Matzel E, Grand S P. 2006. Upper mantle seismic structure beneath eastern Mexico determined from P and S waveform inversion and its implications. J. Geophys. Res., 111(B8): B08307, doi:10.1029/2006JB004304. Dueker K, Jasbinsek J J. 2007. Ubiquitous low-velocity layer atop the 410 km discontinuity beneath the northern Rocky Mountains. Geochem. Geophy. Geosy., 8, Q10004, doi:10.1029/2007GC001661. Jasbinsek J J, Dueker K G, Hansen S M. 2010. Characterizing the 410 km discontinuity low-velocity layer beneath the LA RISTRA array in the North American Southwest. Geochem. Geophy. Geosy., 11(3): Q03008, doi:10.1029/2009GC002836. Hirth G, Kohlstedt D L. 1996. Water in the oceanic upper mantle: implications for rheology, melt extraction and the evolution of the lithosphere. Earth Planet. Sci. Lett., 144(1-2): 93-108. Huang J L, Zhao D P. 2006. High-resolution mantle tomography of China and surrounding regions. J. Geophys. Res., 111(B9): B09305, doi:10.1029/2005JB004066. Kennett B L N, Engdahl E R. 1991. Traveltimes for global earthquake location and phase identification. Geophys. J. Int., 105(2): 429-465. Kennett B L N, Engdahl E R, Buland R. 1995. Constraints on seismic velocities in the Earth from traveltimes. Geophys. J. Int., 122(1): 108-124. Lawrence J F, Shearer P M. 2008. Imaging mantle transition zone thickness with SdS-SS finite-frequency sensitivity kernels. Geophys. J. Int., 174(1): 143-158. Li C, Van Der Hilst R D. 2010. Structure of the upper mantle and transition zone beneath Southeast Asia from traveltime tomography. J. Geophys. Res., 115(B7): B07308, doi:10.1029/2009JB006882. Li J, Wang X, Wang X J, et al. 2013. P and SH velocity structure in the upper mantle beneath Northeast China: Evidence for a stagnant slab in hydrous mantle transition zone. Earth Planet. Sci. Lett., 367: 71-81. Liu Q Y, Li Y, Chen J H, et al. 2010. Joint inversion of receiver function and ambient noise based on Bayesian theory. Chinese J. Geophys., 53(11): 2603-2612. Li Z X, Li X H, Kinnyc P D. 2003. Geochronology of Neoproterozoic syn-rift magmatism in the Yangtze Craton, South China and correlations with other continents: evidence for a mantle superplume that broke up Rodinia. Precambrian Res., 122(1-4): 85-109. Li Z X, Li X H. 2007. Formation of the 1300 km-wide intracontinental orogen and postorogenic magmatic province in Mesozoic South China: A flat-slab subduction model. Geology, 35(2): 179-182. Obayashi M, Sugioka H, Yoshimitsu J, et al. 2006. High temperature anomalies oceanward of subducting slabs at the 410 km discontinuity. Earth Planet. Sci. Lett., 243(1-2): 149-158. Oreshin S I, Vinnik L P, Kiselev S G, et al. 2011. Deep seismic structure of the Indian shield, western Himalaya, Ladakh and Tibet. Earth Planet. Sci. Lett., 307(3-4): 415-429. Qu C, Zhou H L, Zhao D P. 2007. Deep structure beneath the west margin of Philippine Sea Plate and South China Sea from P and S wave travel time tomography. Chinese J. Geophys. (in Chinese), 50(6): 1757-1768. Revenaugh J, Sipkin S A. 1994. Seismic evidence for silicate melt atop the 410 km mantle discontinuity. Nature, 369(6480): 474-476. Sakamaki T, Suzuki A, Ohtani E. 2006. Stability of hydrous melt at the base of the Earth's upper mantle. Nature, 439(7073): 192-194. Schaeffer A J, Bostock M G. 2010. A low-velocity zone atop the transition zone in northwestern Canada. J. Geophys. Res., 115(B6): B06302, doi:10.1029/2009JB006856. Smyth J R, Frost D J. 2002. The effect of water on the 410 km discontinuity: an experimental study. Geophys. Res. Lett., 29(10), 1485, doi:10.1029/2001GL014418. Song T R A, Helmberger D V, Grand S P. 2004. Low-velocity zone atop the 410 km seismic discontinuity in the northwestern United States. Nature, 427(6974): 530-533. Tajima F, Grand S P. 1998. Variation of transition zone high-velocity anomalies and depression of 660 km discontinuity associated with subduction zones from the southern Kuriles to Izu-Bonin and Ryukyu. J. Geophys. Res., 103(B7): 15015-15036. Tauzin B, Debayle E, Wittlinger G. 2010. Seismic evidence for a global low-velocity layer within the Earth's upper mantle. Nature Geosci., 3(10): 718-721. Tian Y, Hung S H, Nolet G, et al. 2007. Dynamic ray tracing and traveltime corrections for global seismic tomography. J. Comput. Phys., 226(1): 672-687. Tian X B, Teng J W, Zhang H S, et al. 2011. Structure of crust and upper mantle beneath the Ordos Block and the Yinshan Mountains revealed by receiver function analysis. Phys. Earth Planet. Inter., 184(3-4): 186-193. Vinnik L, Farra V. 2002. Subcratonic low-velocity layer and flood basalts. Geophys. Res. Lett., 29(4): 1049, doi:10.1029/2001GL014064. Vinnik L, Farra V. 2007. Low S velocity atop the 410 km discontinuity and mantle plumes. Earth Planet. Sci. Lett., 262(3-4): 398-412. Vinnik L, Kumar M R, Kind R, et al. 2003. Super-deep low-velocity layer beneath the Arabian plate. Geophys. Res. Lett., 30(7): 1415, doi:10.1029/2002GL016590. Vinnik L, Ren Y, Stutzmann E, et al. 2010. Observations of S410p and S350p phases at seismograph stations in California. J. Geophys. Res., 115(B5): B05303, doi:10.1029/2009JB006582. Wang B S, Niu F L. 2010. A broad 660 km discontinuity beneath northeast China revealed by dense regional seismic networks in China. J. Geophys. Res., 115(B6), doi: 10.1029/2009JB006608. Wang R J. 1999. A simple orthonormalization method for stable and efficient computation of Green's functions. Bull. Seism. Soc. Am., 89(3): 733-741. Wang T, Chen L. 2009. Distinct velocity variations around the base of the upper mantle beneath northeast Asia. Phys. Earth Planet. Inter., 172(3-4): 241-256. Wang Y, Wen L X, Weidner D, et al. 2006. SH velocity and compositional models near the 660 km discontinuity beneath South America and northeast Asia. J. Geophys. Res., 111(B7), B07305, doi:10.1029/2005JB003849. Wittlinger G, Farra V. 2007. Converted waves reveal a thick and layered tectosphere beneath the Kalahari super-craton. Earth Planet. Sci. Lett., 254(3-4): 404-415. Xu W W, Zheng T Y, Zhao L. 2011. Mantle dynamics of the reactivating North China Craton: Constraints from the topographies of the 410 km and 660 km discontinuities. Sci. China Earth Sci., 54(6): 881-887, doi:10.1007/s11430-010-4163-0. Ye L L, Li J. 2012. Detecting velocity structure around 660 km discontinuity beneath Northeastern China. Acta Seismol. Sin. (in Chinese), 34(2): 137-146. Zhang R Q, Wu Q J, Li Y H, et al. 2012. Lateral variations in SH velocity structure of the transition zone beneath Korea and adjacent regions. J. Geophys. Res., 117, B09315, doi:10.1029/2011JB008900. Zhang R Q, Wu Q J, Li Y H, et al. 2011. Differential patterns of SH and P wave velocity structures in the transition zone beneath northwestern Tibet. Sci. China Earth Sci., 54(10): 1551-1562, doi: 10.1007/s11430-011-4228-8. Zhao D P, Yu S, Ohtani E. 2011. East Asia: Seismotectonics, magmatism and mantle dynamics. J. Asian Earth Sci., 40(3): 689-709. Zhou X M, Li W X. 2000. Origin of Late Mesozoic igneous rocks in Southeastern China: implications for lithosphere subduction and underplating of mafic magmas. Tectonophysics, 326(3-4): 269-287.
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