Multi-scale analysis to the gravity field of the northeastern Tibetan plateau and its geodynamic implications
-
摘要: 由于受到SN和EW双向挤压作用的综合影响,处于年轻高原与古老地块交接区的青藏高原东北部岩石圈强烈变形,构造活动十分活跃.为了整体性地了解青藏高原东北部重力场和深部动力学机制,本文基于EGM2008全球重力场模型数据,利用小波多尺度分析获得不同尺度的重力异常信息;同时反演了研究区的地壳厚度;通过构建穿越龙门山造山带和西秦岭造山带两条剖面的岩石圈密度结构模型,分析了地壳上地幔内不同介质的分布特征.研究结果表明,青藏高原东北部岩石圈显示十分复杂的塑性体的特征,其重力异常走向多以EW或SSE为主,反映了高原岩石圈物质向东运移的趋势;地壳厚度由西向东逐渐减薄,边缘造山带深部并没有发现"山根"痕迹,结合该地区低重力的特征,推测西秦岭-松潘构造结岩石圈发生过大规模地幔流底侵作用;地幔流上涌的动力可能来源于印度板块向欧亚大陆板块俯冲,激发了地幔流体侧向移动,在扬子地台和华北地台附近受到坚硬岩石圈的阻挡而被迫上移,并因此造成龙门山与西秦岭的隆升.Abstract: Affected by both N-S and E-W directed compression,the lithosphere of the northeastern Tibetan plateau, located in the junction region of the youngest plateau and ancient blocks,has experienced active tectonic motions and intense deformation. Such dynamic processes should have left signatures in the gravity field of this region. To understand the gravity field and its relation to deep structure of the northeastern Tibetan plateau,this work made a multi-scale wavelet to the data from the Earth Gravitation Model 2008 (EGM2008) of this region. Our analysis separated the Bouguer gravity anomalies into different parts of shallow to deep and then estimated the corresponding source depths by logarithmic power spectrum technique. Moreover,we calculated the crust thickness and described the Moho topography. The two lithosphere density models respectively across the Longmen Shan orogenic belt and the western Qinling orogenic belt have been constructed, which permit to reveal the distribution features of the different materials in the crust and uppermost mantle beneath the study area. #br#The results show that the crust-mantle structure in northeastern Tibetan plateau is different from that of the peripheral areas. The Sichuan basin,the Ordos basin and the Qilian block have homogeneous and rigid crust-mantle structure on the whole. While the crust-mantle materials in the Tibetan plateau are heterogeneous and plastic,where gravity anomalies strike dominantly in EW and SSE. It is inferred that the lithosphere materials extrude towards east in the interior of the Tibetan plateau,and then turn to south due to resistance of the Yangtze and the North China platforms in the margin of the plateau. The image of the crust thickness indicates that the northeastern Tibetan plateau gradually thins from west to east. However,there is no trace of "mountain roots" under the peripheral orogenic belts. Instead,the Moho below these areas uplifts. Combined with the low gravity anomalies,this study suggests that the upwelling mantle heat-flow interacts with the substances in upmost mantle and lower crust,uplifting the Moho or forming the new shallow Moho.#br#We infer that under the influence of the northward motion of the Indian plate,thermal activity may have occurred in the Qiangtang block lithosphere,and then induced thermal mantle flow. This mantle flow shifts toward east along the asthenospheric channel. Due to the obstruction of the rigid lithosphere in the Yangtze platform and the North China platform, the mantle flow is forced to rise up in the western Qinling-Songpan tectonic node. The uplift of the Longmen Shan and the western Qinling as well as the generation mechanism of earthquakes in the western Sichuan and Gansu province may be all related to this dynamic process.
-
Key words:
- Northeastern Tibetan plateau /
- Gravity field /
- Lithosphere structure /
- Density model /
- EGM2008
-
-
[1] An M J, Shi Y L. 2006. Lithospheric thickness of the Chinese continent. Phys. Earth Planet. Int., 159(3-4):257-266.
[2] Bai D H, Unsworth M J, Meju M A, et al. 2010. Crustal deformation of the eastern Tibetan plateau revealed by magnetotelluric imaging. Nature Geoscience, 3(5):358-362.
[3] Chen S, Xu W M, Shi L, et al. 2013. Gravity field and lithospheric mechanical properties of Longmenshan fault zone and its surrounding areas. Acta Seismologica Sinica (in Chinese), 35(5):692-703.
[4] Clark M K, Royden L H. 2000. Topographic ooze:Building the eastern margin of Tibet by lower crustal flow. Geology, 28(8):703-706.
[5] Deng Q D, Zhang P Z, Ran Y K, et al. 2002. Basic feature of China active structures. Science in China (Series D) (in Chinese), 32(12):1020-1030.
[6] Duan H R, Zhang Y Z, Liu F, et al. 2010. Crustal thickness computed by using satellite gravity data in China and its adjacent regions. Progress in Geophys. (in Chinese), 25(2):494-499, doi:10.3969/j.issn.1004-2903.2010.02.016.
[7] England P, Houseman G. 1986. Finite strain calculations of continental deformation:2. Comparison with the India-Asia collision zone. J. Geophys. Res., 91(B3):3664-3676.
[8] Feng R H, Dong P, Wang L S, et al. 2014. Inversion of Moho interface in northeastern China with prior information. Journal of Earth Science, 25(1):146-151, doi:10.1007/s12583-014-0407-9.
[9] Fu G Y, Zhu Y Q, Gao S H, et al. 2013. Discrepancies between free air gravity anomalies from EGM2008 and the ones from dense gravity/GPS observations at west Sichuan Basin. Chinese J. Geophys. (in Chinese), 56(11):3761-3769, doi:10.6038/cjg20131117.
[10] Gao R, Ma Y S, Li Q S, et al. 2006. Structure of the lower crust beneath the Songpan block and West Qinling orogen and their relation as revealed by deep seismic reflection profiling. Geological Bulletin of China (in Chinese), 25(12):1361-1367.
[11] Gao R, Xiong X S, Li Q S, et al. 2009. The Moho depth of Qinghai-Tibet Plateau revealed by seismic detection. Acta Geoscientia Sinica (in Chinese), 30(6):761-773.
[12] Gao R, Wang H Y, Zeng L S, et al. 2014. The crust structures and the connection of the Songpan block and West Qinling orogen revealed by the Hezuo-Tangke deep seismic reflection profiling. Tectonophysics, 634:227-236.
[13] He J K, Lu S J, Wang W M. 2013. Three-dimensional mechanical modeling of the GPS velocity field around the northeastern Tibetan plateau and surrounding regions. Tectonophysics, 584:257-266.
[14] Hou Z Z, Yang W C. 1997. Wavelet transform and multi-scale analysis on gravity anomalies of China. Chinese J. Geophys. (Acta Geophysica Sinica) (in Chinese), 40(1):85-95.
[15] Jia S X, Zhang X K. 2008. Study on the crust phases of deep seismic sounding experiments and fine crust structures in the northeast margin of Tibetan plateau. Chinese J. Geophys. (in Chinese), 51(5):1431-1443.
[16] Jia S X, Zhang X K, Zhao J R, et al. 2010. Deep seismic sounding data reveal the crustal structures beneath Zoige basin and its surrounding folded orogenic belts. Science China Earth Sciences, 53(2):203-212, doi:10.1007/s11430-009-0166-0.
[17] Jiang W L, Zhang J F, Tian T, et al. 2012. Crustal structure of Chuan-Dian region derived from gravity data and its tectonic implications. Phys. Earth Planet. Int., 212-213:76-87.
[18] Jiménez-Munt I, Fernàndez M, Vergés J, et al. 2008. Lithosphere structure underneath the Tibetan Plateau inferred from elevation, gravity and geoid anomalies. Earth Planet. Sci. Lett., 267(1-2):276-289.
[19] Jin S, Zhang L T, Jin Y J, et al. 2012. Crustal electrical structure along the Hezuo-Dajing profile across the Northeastern Margin of the Tibetan Plateau. Chinese J. Geophys. (in Chinese), 55(12):3979-3990, doi:10.6038/j.issn.0001-5733.2012.12.010.
[20] Kumar P, Yuan X H, Kind R, et al. 2006. Imaging the colliding Indian and Asian lithospheric plates beneath Tibet. J. Geophys. Res.-Solid Earth, 111:B06308, doi:10. 1029/2005JB003930.
[21] Lai S C, Qin J F, Zhao S W, et al. 2014. Geochemistry and its continental dynamic implication of the Cenozoic sodic picritic basalt from the Liuping area, northeastern margin of the Tibetan Plateau. Acta Petrologica Sinica (in Chinese), 30(2):361-370.
[22] Li H Y, Shen Y, Huang Z X, et al. 2014. The distribution of the mid-to-lower crustal low-velocity zone beneath the northeastern Tibetan Plateau revealed from ambient noise tomography. J. Geophys. Res., 119(3):1954-1970.
[23] Li Y H, Wu Q J, Zhang F X, et al. 2011. Seismic anisotropy of the Northeastern Tibetan Plateau from shear wave splitting analysis. Earth Planet. Sci. Lett., 304(1-2):147-157.
[24] Liang S M, Gan W J, Shen C Z, et al. 2013. Three-dimensional velocity field of present-day crustal motion of the Tibetan Plateau derived from GPS measurements. J. Geophys. Res., 118(10):5722-5732.
[25] Lin C Y, Wu Y X, Yang C F. 1995. On the high conductive layer near the Moho and the transitional zone between the crust and mantle in Tianshui region. Acta Seismologica Sinica (in Chinese), 17(2):230-236.
[26] Liu M J, Mooney W D, Li S L, et al. 2006. Crustal structure of the northeastern margin of the Tibetan plateau from the Songpan-Ganzi terrane to the Ordos basin. Tectonophysics, 420(1-2):253-266.
[27] Ma K Y, Xue G Q, Dong Y J, et al. 1996. Uplift of Qinghai-Xizang (Tibet) Plateau and mantle deformation due to partial melting. Acta Geoscientia Sinica (in Chinese), 17(2):214-223.
[28] Mallat S G. 1989. A theory for multiresolution signal decomposition:the wavelet representation. IEEE Transactions on Pattern Analysis and Machine Intelligence, 11(7):674-693.
[29] Meng X H, Shi L, Guo L H, et al. 2012. Multi-scale analyses of transverse structures based on gravity anomalies in the northeastern margin of the Tibetan Plateau. Chinese J. Geophys. (in Chinese), 55(12):3933-3941, doi:10.6038/j.issn.0001-5733.2012.12.006.
[30] Mo X X, Zhao Z D, Deng J F, et al. 2007. Migration of the Tibetan Cenozoic potassic volcanism and its transition to eastern basaltic province:implications for crustal and mantle flow. Geoscience (in Chinese), 21(2):255-264.
[31] Molnar P, Tapponnier P. 1975. Cenozoic tectonics of Asia:effects of a continental collision. Science, 189(4201):419-426.
[32] Oldenburg D W. 1974. The inversion and interpretation of gravity anomalies. Geophysics, 39(4):526-536.
[33] Owens T J, Zandt G. 1997. Implications of crustal property variations for models of Tibetan plateau evolution. Nature, 387(6628):37-43.
[34] Pan G T, Zhu D C, Wang L Q, et al. 2004. Bangong Lake-Nu River suture zone-the northern boundary of Gondwanaland:Evidence from geology and geophysics. Earth Science Frontiers (in Chinese), 11(4):371-382.
[35] Pan S Z, Niu F L. 2011. Large contrasts in crustal structure and composition between the Ordos plateau and the NE Tibetan plateau from receiver function analysis. Earth Planet. Sci. Lett., 303(3-4):291-298.
[36] Parker R L. 1973. The rapid calculation of potential anomalies. Geophys. J. Int., 31(4):447-455.
[37] Pavlis N, Kenyon S, Factor J, et al. 2008. Earth gravitational model 2008.//SEG Technical Program Expanded Abstracts. Las Vegas, Nevada:SEG, 761-763.
[38] Royden L H, Burchfiel B C, King R W, et al. 1997. Surface deformation and lower crustal flow in eastern Tibet. Science, 276(5313):788-790.
[39] Tang Q Y, Zhang M J, Li X Y, et al. 2012. The chemical and carbon isotopic compositions of volatiles in Cenozoic high-potassic basalts in western Qinling, China and their mantle geodynamic implications. Acta Petrologica Sinica (in Chinese), 28(4):1251-1260.
[40] Tapponnier P, Xu Z Q, Roger F, et al. 2001. Oblique stepwise rise and growth of the Tibet plateau. Science, 294(5547):1671-1677.
[41] Tian X B, Zhang Z J. 2013. Bulk crustal properties in NE Tibet and their implications for deformation model. Gondwana Res., 24(2):548-559.
[42] Tilmann F, Ni J, INDEPTH III Seismic Team. 2003. Seismic imaging of the downwelling Indian lithosphere beneath central Tibet. Science, 300(5624):1424-1427.
[43] Vergne J, Wittlinger G, Farra V, et al. 2003. Evidence for upper crustal anisotropy in the Songpan-Ganze (northeastern Tibet) terrane. Geophys. Res. Lett., 30(11):1552, doi:10.1029/2002GL016847.
[44] Wang X B, Zhang G, Fang H, et al. 2014. Crust and upper mantle resistivity structure at middle section of Longmenshan, eastern Tibetan plateau. Tectonophysics, 619-620:143-148.
[45] Wang Y X, Mooney W D, Yuan X C, et al. 2013. Crustal structure of the northeastern Tibetan Plateau from the Southern Tarim Basin to the Sichuan Basin, China. Tectonophysics, 584:191-208.
[46] Wang Z, Zhao D P, Wang J A. 2010. Deep structure and seismogenesis of the north-south seismic zone in southwest China. J. Geophys. Res., 115(B12):B12334.
[47] Wessel P, Smith W H F. 1991. Free software helps map and display data. Eos. Trans. AGU, 72(41):441-446.
[48] Xiao Q B, Zhang J, Zhao G Z, et al. 2013. Electrical resistivity structures northeast of the Eastern Kunlun Fault in the Northeastern Tibet:Tectonic implications. Tectonophysics, 601:125-138.
[49] Xiong X, Wang J Y, Teng J W. 2007. Deep mechanical background for the Cenozoic volcanism in the Tibetan plateau. Earth Science (Journal of China University of Geosciences) (in Chinese), 32(1):1-6.
[50] Xu Z Q, Hou L W, Wang Z X, et al. 1992. Orogenic Processes of the Songpan-Ganze Orogenic Belt of China (in Chinese). Beijing:Geological Publishing House.
[51] Xue G Q, Qian H, Jiang M, et al. 2003. Studies on the velocity structure of crust-upper mantle beneath northeast Qinghai-Tibet Plateau, China. Acta Geoscientia Sinica (in Chinese), 24(1):19-26.
[52] Yang J Y, Zhang X H, Zhang F F, et al. 2012. On the accuracy of EGM2008 earth gravitational model in Chinese Mainland. Progress in Geophys. (in Chinese), 27(4):1298-1306, doi:10.6038/j.issn.1004-2903.2012.04.003.
[53] Yang X S, Jin Z M, Ma J, et al. 2002. Genesis of SKS splitting in the north-central Qinghai-Xizang plateau:melt alignment enhanced lithosphere anisotropy. Chinese J. Geophys. (in Chinese), 45(6):821-831.
[54] Yin A, Harrison T M. 2000. Geologic evolution of the Himalayan-Tibetan orogen. Annu. Rev. Earth Plant. Sci., 28:211-280.
[55] Yu X H, Mo X X, Zhao Z D, et al. 2009. Two types of Cenozoic potassic volcanic rocks in West Qinling, Gansu Province:Their petrology, geochemistry and petrogenesis. Earth Science Frontiers (in Chinese), 16(2):79-89.
[56] Zhang C Y, Guo C X, Chen J Y, et al. 2009. EGM 2008 and its application analysis in Chinese mainland. Acta Geodaetica et Cartographica Sinica (in Chinese), 38(4):283-289.
[57] Zhang G W, Guo A L, Yao A P. 2004. Western Qinling-Songpan continental tectonic node in China's continental tectonics. Earth Science Frontiers (in Chinese), 11(3):23-32.
[58] Zhang J S, Gao R, Zeng L S, et al. 2010. Relationship between characteristics of gravity and magnetic anomalies and the earthquakes in the Longmenshan range and adjacent areas. Tectonophysics, 491(1-4):218-229.
[59] Zhang L T, Jin S, Wei W B, et al. 2012. Electrical structure of crust and upper mantle beneath the eastern margin of the Tibetan plateau and the Sichuan basin. Chinese J. Geophys. (in Chinese), 55(12):4126-4137, doi:10.6038/j.issn.0001-5733.2012.12.025.
[60] Zhang P Z, Shen Z K, Wang M, et al. 2004. Continuous deformation of the Tibetan Plateau from global positioning system data. Geology, 32(9):809-812.
[61] Zhang Z J, Klemperer S, Bai Z M, et al. 2011. Crustal structure of the Paleozoic Kunlun orogeny from an active-source seismic profile between Moba and Guide in East Tibet, China. Gondwana Res., 19(4):994-1007.
[62] Zhang Z J, Bai Z M, Klemperer S L, et al. 2013. Crustal structure across northeastern Tibet from wide-angle seismic profiling:Constraints on the Caledonian Qilian orogeny and its reactivation. Tectonophysics, 606:140-159.
[63] Zhao G Z, Tang J, Zhan Y, et al. 2005. Relation between electricity structure of the crust and deformation of crustal blocks on the northeastern margin of Qinghai-Tibet plateau. Science China Earth Sciences, 48(10):1613-1626.
[64] Zhu L P, Helmberger D V. 1998. Moho offset across the northern margin of the Tibetan Plateau. Science, 281(5380):1170-1172.
[65] 陈石, 徐伟民, 石磊等. 2013. 龙门山断裂带及其周边地区重力场和岩石层力学特性研究. 地震学报, 35(5):692-703.
[66] 邓起东, 张培震, 冉勇康等. 2002. 中国活动构造基本特征. 中国科学(D辑:地球科学), 32(12):1020-1030.
[67] 段虎荣, 张永志, 刘锋等. 2010. 利用卫星重力数据研究中国及邻域地壳厚度. 地球物理学进展, 25(2):494-499, doi:10.3969/j.issn.1004-2903.2010.02.16.
[68] 付广裕, 祝意青, 高尚华等. 2013. 川西地区实测自由空气重力异常与EGM2008模型结果的差异. 地球物理学报, 56(11):3761-3769, doi:10.6038/cjg20131117.
[69] 高锐, 马永生, 李秋生等. 2006. 松潘地块与西秦岭造山带下地壳的性质和关系——深地震反射剖面的揭露. 地质通报, 25(12):1361-1367.
[70] 高锐, 熊小松, 李秋生等. 2009. 由地震探测揭示的青藏高原莫霍面深度. 地球学报, 30(6):761-773.
[71] 侯遵泽, 杨文采. 1997. 中国重力异常的小波变换与多尺度分析. 地球物理学报, 40(1):85-95.
[72] 嘉世旭, 张先康. 2008. 青藏高原东北缘深地震测深震相研究与地壳细结构. 地球物理学报, 51(5):1431-1443.
[73] 嘉世旭, 张先康, 赵金仁等. 2009. 若尔盖盆地及周缘褶皱造山带地壳结构——深地震测深结果. 中国科学(D辑:地球科学), 39(9):1200-1208.
[74] 金胜, 张乐天, 金永吉等. 2012. 青藏高原东北缘合作—大井剖面地壳电性结构研究. 地球物理学报, 55(12):3979-3990, doi:10.6038/j.issn.0001-5733.2012.12.010.
[75] 赖绍聪, 秦江锋, 赵少伟等. 2014. 青藏高原东北缘柳坪新生代苦橄玄武岩地球化学及其大陆动力学意义. 岩石学报, 30(2):361-370.
[76] 林长佑, 武玉霞, 杨长福. 1995. 天水地区莫霍面附近的高导层及壳幔过渡带. 地震学报, 17(2):230-236.
[77] 马开义, 薛光琦, 董英君等. 1996. 地幔内异常热熔变与青藏高原的隆升. 地球学报, 17(2):214-223.
[78] 孟小红, 石磊, 郭良辉等. 2012. 青藏高原东北缘重力异常多尺度横向构造分析. 地球物理学报, 55(12):3933-3941, doi:10.6038/j.issn.0001-5733.2012.12.006.
[79] 莫宣学, 赵志丹, 邓晋福等. 2007. 青藏新生代钾质火山活动的时空迁移及向东部玄武岩省的过渡:壳幔深部物质流的暗示. 现代地质, 21(2):255-264.
[80] 潘桂棠, 朱弟成, 王立全等. 2004. 班公湖—怒江缝合带作为冈瓦纳大陆北界的地质地球物理证据. 地学前缘, 11(4):371-382.
[81] 汤庆艳, 张铭杰, 李晓亚等. 2012. 西秦岭新生代高钾质玄武岩流体组成及其地幔动力学意义. 岩石学报, 28(4):1251-1260.
[82] 熊熊, 王继业, 滕吉文. 2007. 青藏高原新生代火山活动的深部力学背景. 地球科学(中国地质大学学报), 32(1):1-6.
[83] 许志琴, 侯立玮, 王宗秀等. 1992. 中国松潘—甘孜造山带的造山过程. 北京:地质出版社.
[84] 薛光琦, 钱辉, 姜枚等. 2003. 青藏高原东北部天然地震探测与岩石圈深部特征. 地球学报, 24(1):19-26.
[85] 杨金玉, 张训华, 张菲菲等. 2012. EGM2008地球重力模型数据在中国大陆地区的精度分析. 地球物理学进展, (4):1298-1306, doi:10.6038/j.issn.1004-2903.2012.04.003
[86] 杨晓松, 金振民, 马瑾等. 2002. 青藏高原北部异常SKS分裂成因的初步探讨——被熔体强化的岩石圈各向异性. 地球物理学报, 45(6):821-831.
[87] 喻学惠, 莫宣学, 赵志丹等. 2009. 甘肃西秦岭两类新生代钾质火山岩:岩石地球化学与成因. 地学前缘, 16(2):79-89.
[88] 章传银, 郭春喜, 陈俊勇等. 2009. EGM 2008地球重力场模型在中国大陆适用性分析. 测绘学报, 38(4):283-289.
[89] 张国伟, 郭安林, 姚安平. 2004. 中国大陆构造中的西秦岭—松潘大陆构造结. 地学前缘, 11(3):23-32.
[90] 张乐天, 金胜, 魏文博等. 2012. 青藏高原东缘及四川盆地的壳幔导电性结构研究. 地球物理学报,55(12):4126-4137, doi:10.6038/j.issn.0001-5733.2012.12.025.
[91] 赵国泽, 汤吉, 詹艳等. 2004. 青藏高原东北缘地壳电性结构和地块变形关系的研究. 中国科学(D辑:地球科学), 48(10):908-918.
-
计量
- 文章访问数:
- PDF下载数:
- 施引文献: 0
下载: