接收函数和背景噪声联合反演下扬子地区精细岩石圈结构

下扬子地区作为扬子陆块最靠东的部分，西南狭窄、东北宽阔，整体呈北东-南西走向，是多个构造单元的交汇处。为了研究该地区地壳及岩石圈上地幔结构，本文整合了研究区域内240个台站两年左右的接收函数与背景噪声数据，台站布设的经度范围为[118.5E, 122.5E]，纬度范围为[27.9N, 34.3N]。通过收集该批台站的远震波形数据，本文首先利用P波接收函数约束岩石圈内间断面。接收函数的结果显示，整个研究区域内地壳厚度在26-36km范围内变化，Vp/Vs值在1.60-1.90范围内变化。然后利用背景噪声互相关方法对17020个台站对做互相关计算，从垂向分量的互相关波形中提取瑞利波频散曲线，得到了4-38s周期的瑞利波相速度分布图。将接收函数和背景噪声联合反演，最终得到研究区域内从地表到地下60km范围内较为精细的岩石圈S波速度结构。

接收函数的结果表明：1.整个区域的地壳厚度在26-36km，在不同的块体之间整体呈现较为平滑的变化。郯庐断裂东部的苏北盆地、长江三角洲平原、秦岭-大别造山带以南的鄱阳湖盆地这三块区域地壳出现明显减薄。三块明显减薄的区域地壳平均厚度在28-30km，大别造山带和江南隆起的地壳平均厚度在34km以上。长江中下游成矿带是一个Moho面较浅的薄弱带，其可能是华南华北两大块体在中生代发生碰撞拼合的前缘位置。2.研究区整体Vp/Vs值较低，反映了经中生代拆沉作用后地壳整体的组分偏酸性，即酸性长英质组分相对于基性镁铁质组分下地壳较厚。大别造山带和华夏地块的Vp/Vs偏高，前者是由于高压/超高压变质岩的存在，而后者则是保留了部分偏基性物质。

S波速度结构表明：1.苏北盆地和丽水-余姚断裂以东的华夏块体两个明显的上涌中心。苏北盆地在新生代受到拉张作用而伸展，丽水-余姚断裂以东狭长的区域岩石圈比较薄，此处可见一系列的新生代火山岩，判断此处可能存在地幔上升流。2.大别造山带存在着明显的“上地壳高速，下地壳低速”结构。大别造山带浅部地壳的高速结构与其地表地形以及广泛出露的高压/超高压变质岩相一致，且这种高速异常在15km深度之内。而下地壳的低速结构可能代表高压/超高压变质岩折返过程中形成的韧性剪切带或脆性断裂带，也可能是岩石圈伸展导致的拆沉作用所致。3.江南隆起属于江南造山带的东北缘，为扬子克拉通内部的陆内造山带。反演结果显示，江南隆起下方整个地壳均显示明显的高速异常且异常值高于大别造山带，这种地壳普遍高速现象反映了其作为华南板块内部造山带的构造稳定性。根据结合江南隆起下Moho面的深度变化以及前人的重力学资料，江南隆起下方地壳的明显加厚和高速异常可能为古老扬子克拉通核的残留。

[1]刘训,游国庆.中国的板块构造区划[J].中国地质,2015,42(01):1-17.
[2]张昌榕,张贵宾,江国明,等.下扬子及周边地区深部泊松比结构及深部动力过程约束研究[J].地球物理学报,2018,61(11):4418-4435.
[3]LI C M, ZHANG C H, TIM D C, et al. Out-of-sequence thrusting in polycyclic thrust belts: An example from the Mesozoic Yanshan belt, North China Craton[J]. Tectonics,2016,35(9).
[4]李廷栋.中国岩石圈的基本特征[J].地学前缘,2010,17(03):1-13.
[5]索艳慧,李三忠,戴黎明,等.东亚及其大陆边缘新生代构造迁移与盆地演化[J].岩石学报,2012,28(08):2602-2618.
[6]张国伟,郭安林,王岳军,等.中国华南大陆构造与问题[J].中国科学:地球科学,2013,43(10):1553-1582.
[7]YAN D P, ZHOU M F, SONG H L, et al. Origin and tectonic significance of a Mesozoic multi-layer over-thrust system within the Yangtze Block (South China)[J]. Tectonophysics,2003,361:239-254.
[8]ZHAO G, CAWOOD P A. Precambrian geology of China[J]. Precambrian Research, 2012, 222–223:13-54.
[9]王孝磊,周金城,陈昕,等.江南造山带的形成与演化[J].矿物岩石地球化学通报,2017. 36: 714-735+696.
[10]舒良树.华南构造演化的基本特征[J].地质通报, 2012.31: 1035-1053.
[11]叶卓,李秋生,张洪双,等.下扬子及其邻区地壳和上地幔结构的接收函数研究及其地质意义[J].地质学报,2020,94(3):707-715.
[12]陈毓川,王登红,徐志刚,等.华南区域成矿和中生代岩浆成矿规律概要[J].大地构造与成矿学,2014,38(02):219-229.
[13]ZHENG Y F, FU B, GONG B, et al. Stable isotope geochemistry of ultrahigh pressure metamorphic rocks from the Dabie-Sulu orogen in China: implications for geodynamics and fluid regime[J]. Earth-Science Reviews,2003,62(1/2):105-161.
[14]HACKER B R, WEBB L, MCWILLIAMS M, et al. Exhumation of ultrahigh-pressure continental crust in east central China: Late Triassic-Early Jurassic tectonic unroofing[J]. Journal of Geophysical Research. Biogeosciences,2000,105(B6):13339-13364.
[15]MASSONNE H J. Involvement of Crustal Material in Delamination of the Lithosphere after Continent-Continent Collision[J]. International Geology Review,2005,47(8):792-804.
[16]XU Y X, ZHANG S, GRIFFIN W L, et al. How did the Dabie Orogen collapse? Insights from 3-D magnetotelluric imaging of profile data[J]. Journal of Geophysical Research: Solid Earth,2016,121(7):5169-5158.
[17]李曙光,黄方,周红英,等.大别山双河超高压变质岩及北部片麻岩的U-Pb同位素组成——对超高压岩石折返机制的制约[J].中国科学(D辑:地球科学),2001(12):977-984.
[18]李曙光,李秋立,侯振辉,等.大别山超高压变质岩的冷却史及折返机制[J].岩石学报,2005(04):1117-1124.
[19]陈俊,张珣,王辉,等.下扬子地区冶山埃达克质岩的年代学、地球化学特征及其岩石成因[J].华南地质与矿产,2020,36(01):19-32.
[20]资锋,王强,刘新华,等.扬子东部冶山和山里陈埃达克质侵入岩年代学与地球化学:岩石成因和动力学意义[J].矿物学报,2011,31(02):185-200.
[21]周涛发,范裕,王世伟,等.长江中下游成矿带成矿规律和成矿模式[J].岩石学报,2017,33(11):3353-3372.
[22]薛怀民,董树文,马芳.长江中下游庐枞盆地火山岩的SHRIMP锆石U-Pb年龄:对扬子克拉通东部晚中生代岩石圈减薄机制的约束[J].地质学报,2012,86(10):1569-1583.
[23]王强,许继峰,赵振华,等.安徽铜陵地区燕山期侵入岩的成因及其对深部动力学过程的制约[J].中国科学(D辑:地球科学),2003(04):323-334.
[24]LING M X, WANG F Y, DING X, et al. Different origins of adskites from the Dabie Mountains and the Lower Yangtze River Belt,eastern China:geochemical constraints[J]. International Geology Review,2011,53(5/6):727-740.
[25]YANG Y Z, LONG Q, SIEBEL W, et al. Paleo-Pacific Subduction in the Interior of Eastern China: Evidence from Adakitic Rocks in the Edong-Jiurui District[J]. The Journal of Geology: a semi-quarterly magazine of geology and related sciences,2014,122(1):77-97.
[26]王椿镛,张先康,丁志峰,等.大别造山带上部地壳结构的有限差分层析成像[J].地球物理学报,1997(04):495-502.
[27]刘福田,徐佩芬,刘劲松等.大陆深俯冲带的地壳速度结构——东大别造山带深地震宽角反射/折射研究[J].地球物理学报,2003(03):366-372.
[28]杨文采,胡振远,程振炎,等.郯城-涟水综合地球物理剖面[J].地球物理学报,1999(02):206-217.
[29]OUYANG L B, LI H Y, LV Q T, et al. Crustal and uppermost mantle velocity structure and its relationship with the formation of ore districts in the Middle–Lower Yangtze River region[J]. Earth and Planetary Science Letters,2014,408.
[30]LI H Y, SONG X D, LV Q T, et al. Seismic Imaging of Lithosphere Structure and Upper Mantle Deformation Beneath East‐Central China and Their Tectonic Implications[J]. Journal of Geophysical Research: Solid Earth,2018,123(4).
[31]SHI D N, LV Q T, XU W Y, et al. Crustal structure beneath the middle–lower Yangtze metallogenic belt in East China: Constraints from passive source seismic experiment on the Mesozoic intra-continental mineralization[J]. Tectonophysics,2013,606.
[32]SODOUDI F, YUAN X, LIU Q, et al. Lithospheric thickness beneath the Dabie Shan, central eastern China from S receiver functions[J]. Geophysical Journal International,2016, 166(3):1363-1367.
[33]ZHAO T, ZHU G, LIN SZ, et al. Indentation-induced tearing of a subducting continent: Evidence from the Tan-Lu Fault Zone, East China[J]. Earth-Science Reviews,2016,15214-36.
[34]郑朗荪,高维明,郑传贝.郯庐断裂带的分段与沂沭断裂的活动性[J].中国地震,1988(03):129-135.
[35]张鹏,王良书,钟锴,等. 郯庐断裂带的分段性研究[J]. 地质论评,2007,53(5):586-591.
[36]DENG Y F, FAN W M, ZHANG Z J, et al. Geophysical evidence on segmentation of the Tancheng-Lujiang fault and its implications on the lithosphere evolution in East China[J]. Journal of Asian earth sciences,2013,78(Dec.15):263-276.
[37]朱光,王道轩,刘国生,等.郯庐断裂带的演化及其对西太平洋板块运动的响应[J].地质科学,2004(01):36-49.
[38]ZHU G, LIU G S, NIU M L, et al. Syn-collisional transform faulting of the Tan-Lu fault zone, East China[J]. International Journal of Earth Sciences,2009,98,135-155.
[39]郑建平,戴宏坤.西太平洋板片俯冲与后撤引起华北东部地幔置换并导致陆内盆-山耦合[J].中国科学:地球科学,2018,48(04):436-456.
[40]郑永飞,徐峥,赵子福,等.华北中生代镁铁质岩浆作用与克拉通减薄和破坏[J].中国科学:地球科学,2018,48(04):379-414.
[41]朱日祥,徐义刚,朱光,等.华北克拉通破坏[J].中国科学:地球科学,2012,42(08):1135-1159.
[42]HUANG J I, ZHAO D P. High-resolution mantle tomography of China and surrounding regions[J]. Journal of Geophysical Research: Solid Earth,2006,111.
[43]张永谦,徐峣,严加永,等.华南东南部地壳厚度、属性及其与成矿的关系:基于地震接收函数的约束[J].中国地质,2019,46(04):723-736.
[44]徐强,赵俊猛.接收函数方法的研究综述[J].地球物理学进展,2008,23(06):1709-1716.
[45]刘启元,李顺成.接收函数复谱比的最大或然性估计及非线性反演[J].地球物理学 报,1996(04):442-443.
[46]吴庆举,曾融生.用宽频带远震接收函数研究青藏高原的地壳结构[J].地球物理学报,1998(05):669-679.
[47]GURROLA H, BAKER G E, MINSTER J B. Simultaneous time‐domain deconvolution with application to the computation of receiver functions[J]. Geophysical Journal International,1995,120(3):537-543.
[48]吴庆举,田小波,张乃铃,等.计算台站接收函数的最大熵谱反褶积方法[J].地震学报,2003(04):382-389+451.
[49]LIGORRIA J P, AMMON C J. Iterative Deconvolution and Receiver-Function Estimation[J]. Bulletin of the Seismological Society of America,1999,89(5):1395-1400.
[50]HELMBERGER D, WIGGINS R A. Upper mantle structure of midwestern United States[J]. Journal of Geophysical Research,1971,76(14):3229-3245.
[51]陈凌,王旭,王新,等.接收函数界面和波速成像研究进展与展望[J].地球与行星物理论评,2022,53(06):680-701.
[52]YUAN X, Ni J, KIND R, et al. Lithospheric and Upper Mantle Structure of Southern Tibet from a Seismological Passive Source Experiment[J]. Journal of Geophysical Research Atmospheres, 1997,102(B12):325-327.
[53]DUEKER K G, SHEEHAN A F. Mantle discontinuity structure from midpoint stacks of converted P to S waves across the Yellowstone hotspot track[J]. Journal of Geophysical Research, 1997,102(B4),8313-8327.
[54]ZHU L P. Crustal structure across the San Andreas Fault Southern California from teleseismic converted waves[J]. Earth and Planetary Science Letters,2000,179,183-190.
[55]KIND R, YUAN X, KUMAR P. Seismic receiver functions and the lithosphere–asthenosphere boundary[J]. Tectonophysics,2012,536-537,25-43.
[56]RYBERG T, WEBER M. Receiver function arrays: A reflection seismic approach[J]. Geophysical Journal International,2000,141,1-11.
[57]WILSON D, ASTER R. Seismic imaging of the crust and upper mantle using regularized joint receiver functions, frequency-wave number filtering, and multimode Kirchhoff migration[J]. Journal of Geophysical Research,2005,110,B05305.
[58]ZHU L P, KANAMORI H. Moho depth variation in southern California from teleseismic receiver functions[J]. Journal of Geophysical Research. Biogeosciences, 2000,105(B2):2969-2980.
[59]STEIN S, WYSESSION M. An Introduction to Seismology, Earthquakes, and Earth Structure[M]. Oxford,UK:Blackwell Publishing Ltd,2003:97-100.
[60]AKI K. Space and time spectra of stationary stochastic waves, with special reference to microtremors[J]. Bulletin of the Earthquake Research Institute, 35, 415-456.
[61]WEAVER R L, LOBKIS O I. Ultrasonics without a source: Thermal fluctuation correlations at MHz frequencies[J]. Physical review letters, 2001, 87(13): 4301.
[62]SHAPIRO N M, CAMPILLO M. Emergence of broadband Rayleigh waves from correlations of the ambient seismic noise[J]. Geophysical Research Letters, 2004, 31(7).
[63]SHAPIRO N M, CAMPILLO M, STEHLY L, et al. High-Resolution Surface-Wave Tomography from Ambient Seismic Noise[J]. Science, 2005(307):1615-1618.
[64]BENSEN G D, RITZWOLLER M H, BARMIN M P, et al. Processing seismic ambient noise data to obtain reliable broad-band surface wave dispersion measurements[J]. Geophysical Journal International, 2007, 169(3): 1239-1260.
[65]SNIEDER R. Extracting the Green's function from the correlation of coda waves: A derivation based on stationary phase[J]. Physical Review E, 2004, 69(4):046610.
[66]YAO H J, Van D H R D. Analysis of ambient noise energy distribution and phase velocity bias in ambient noise tomography, with application to SE Tibet[J]. Geophysical Journal International, 2009, (2):1113-1132.
[67]LEVSHIN A L, RITZWOLLER M H. Automated Detection, Extraction, and Measurement of Regional Surface Waves[J]. Pure and Applied Geophysics, 2001, 158(8): 1531-1545.
[68]BARMIN M P, RITZWOLLER M H, LEVSHIN A L, et al. A fast and reliable method for surface wave tomography[J]. Pure and Applied Geophysics, 2001, 158(8): 1351–1375.
[69]RAWLINSON N, SAMBRIDGE M. The fast marching method: an effective tool for tomographic imaging and tracking multiple phases in complex layered media[J]. Exploration geophysics,2005,36(4):341-350.
[70]杨志高,陈运泰,张雪梅,等.青藏高原东缘及东北缘S波速度结构和径向各向异性[J].地球物理学报,2019,62(12):4554-4570.
[71]李小勇,朱培民,周强,等.三峡库区上地壳横波速度结构[J].地球科学(中国地质大学学报),2014,39(12):1842-1850.
[72]JULIA J, HERRMANN R B, CORREIG A M, et al. Joint inversion of receiver function and surface wave dispersion observations[J]. Geophysical Journal International, 2000,143(1):99-112.
[73]BODIN T, SAMBRIDGE M, TKALCIC H, et al. Transdimensional inversion of receiver functions and surface wave dispersion[J]. Journal of geophysical research. Solid earth: JGR,2012,117(B2).
[74]SHEN W, RITZWOLLER M H, SCHULTE-PELKUM V, et al. Joint inversion of surface wave dispersion and receiver functions: A Bayesianmonte-Carlo approach[J]. Geophysical Journal International,2013,192(2):807-836.
[75]GREEN P J. Reversible jump Markov chain Monte Carlo computation and Bayesian model determination[J]. Biometrika,1995,82(4):711-732.
[76]ZHAO Y Z, GUO Z, WANG Y B. Asthenospheric Flow From East Asia to the Philippine Sea Plate Revealed by Rj-MCMC Inversion of Surface Waves[J]. Geochemistry, Geophysics, Geosystems:23, e2022GC010342.
[77]SHEN W S, RITZWOLLER M H, KANG D, et al. A seismic reference model for the crust and uppermost mantle beneath China from surface wave dispersion[J]. Geophysical Journal International:2016,206, 954-979.
[78]HERRMANN R B. Computer Programs in Seismology: An Evolving Tool for Instruction and Research[J]. Seismological research letters,2013,84(6):1081-1088.
[79]LUO Y H, XU Y X, YANG Y J. Crustal structure beneath the Dabie orogenic belt from ambient noise tomography[J]. Earth and Planetary Science Letters,2012,313-314,12-22.
[80]LI S G, LI Q L, HOU Z, et al. Cooling history and exhumation mechanism of the ultrahigh-pressure metamorphic rocks in the Dabie mountains, Central China[J]. Acta Petrol. Sin. 21(4),1117–1124(In Chinese with English abstract).
[81]HACKER B R, RATSCHBACHER L, WEBB L E, et al. What brought them up? Exhumation of the Dabie Shan ultrahigh-pressure rocks[J]. Geology,1995,23,743–746.
[82]ZHAO Z, ZHENG Y. Remelting of subducted continental lithosphere: petrogenesis of Mesozoic magmatic rocks in the Dabie–Sulu orogenic belt[J]. Sci.China Ser.D, Earth Sci, 2009,52(9),1295–1318.
[83]朱光,刘国生.皖南江南陆内造山带的基本特征与中生代造山过程[J].大地构造与成矿学,2000,24(2):103-111.