-
摘要:
木里—盐源地区地处青藏高原东南缘，属于古特提斯洋构造域，是松潘—甘孜地块及扬子地块的交接地带，是研究青藏高原东南缘构造演化过程的重要区域.本文介绍的是横穿木里—盐源地区的大地电磁剖面，自北西向南东依次跨越锦屏山断裂、木里弧形构造区、丽江—小金河断裂、盐源盆地、金河—箐河断裂等构造.维性分析表明木里弧形构造区和金河—箐河断裂都表现为较强的三维性，因此本文采用大地电磁三维反演技术，获得了木里—盐源地区的精细电性结构.电性模型显示，沿剖面可以划分为4个主要的电性构造单元.锦屏山断裂以北的川西北次级地块下方10~20 km处，发育北西向低阻体，推断是古老的义敦岛弧区残留的物质；锦屏山断裂以南至丽江—小金河断裂为高阻体，可能是锦屏山山根；丽江—小金河断裂下方~10 km处发育北东向的低阻体，与龙门山—锦屏山构造带走向一致，结合剖面附近表现为张性的震源机制解特点，推测该低阻体很可能是北部的塑性物质受阻后一部分往西南沿着丽江—小金河断裂缝隙挤入的结果；盐源盆地下方在3~7 km发育厚度约5 km、长度达40 km的低阻层，电性主轴方向为北西向，与盐源断裂走向一致，解释为盐岩层，尤其是南段低阻体表现为延伸至地表的特征，与地表盐泉对应，为在盐源地区开展深部找钾盐矿提供了电磁方面的证据.
Abstract:The Muli-Yanyuan area is essential for studying the tectonic evolution process in the southeastern margin of the Tibet Plateau. It belongs to the Paleo-Tethys Ocean structural domain, the junction zone of Songpan-Garzê terrane and Yangtze Block. We obtain one magnetotelluric (MT) profile crossing the Muli-Yanyuan area. From NW to SE, the MT profile across the Jinpingshan fault, Muli arc structural area, Lijiang-Xiaojinhe fault, Yanyuan basin, Jinhe-Qinghe fault, and others. Three-dimensional characteristics exist at the Muli arc structural area and the Jinhe-Qinghe fault based on dimensionality analysis. We used the three-dimensional MT inversion to obtain the Muli-Yanyuan area's electrical structure. The resulting resistivity model reveals four primary electrical structure units. To the north of the Jinpingshan fault, an NW-trending low resistivity layer develops at a depth of 10~20 km beneath the western Sichuan sub-block, which was inferred as the ancient residual material of the Yidun arc. From the south of Jinpingshan fault to the Lijiang-Xiaojinhe fault, a high resistivity body may be the root of Jinpingshan. Beneath the Lijiang-Xiaojinhe fault, a low resistivity body develops at a depth of 10~20 km. The electrical strike is NE-trending and consistent with the trending of the Longmenshan-Jinpingshan thrust belt. Combined with the extensional characteristics of the focal mechanisms, we conclude that this low resistivity body is probably part of the northern ductile materials blocked and squeezed into the southwestern along with the Lijiang-Xiaojinhe fault. There is a continuous low resistivity layer beneath the Yanyuan basin at a depth of 3~7 km. The length and thickness of the low resistivity layer are about 40 km and 5 km. The electrical strike is NW-trending and consistent with the trending of the Yanyuan fault. We interpret it as a halite layer. In particular, the southern part of the low resistivity body that extends to the surface corresponds to the salt spring. We provide electromagnetic evidence to find sylvine ore in the Yanyuan region.
-
Key words:
- Lijiang-Xiaojinhe fault /
- Magnetotellurics /
- Electrical structure /
- Yanyuan basin /
- Seismicity
-
-
图 1
研究区周边构造背景图(a)及大地电磁测深点位分布(b)
Figure 1.
The tectonic setting (a) and locations of magnetotelluric stations in the profile (b)
图 2
多测点-多频点电性主轴统计成像结果
Figure 2.
Electrical strike statistic obtained from multi-sites and multi-frequencies imaging technique
图 5
共主轴多测点多频点阻抗张量分解后的视电阻率和相位拟断面图
Figure 5.
Pseudo section of apparent resistivity and impedance phase after impedance tensor decomposition using a fixed strike
-
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. doi: 10.1038/ngeo830
Bao X W, Sun X X, Xu M J, et al. 2015. Two crustal low-velocity channels beneath SE Tibet revealed by joint inversion of Rayleigh wave dispersion and receiver functions. Earth and Planetary Science Letters, 415: 16-24. doi: 10.1016/j.epsl.2015.01.020
Cai J T, Chen X B, Xu X W, et al. 2017. Rupture mechanism and seismotectonics of the MS6.5 Ludian earthquake inferred from three-dimensional magnetotelluric imaging. Geophysical Research Letters, 44(3): 1275-1285. doi: 10.1002/2016GL071855
Chang Z F, Yang S Y, Zhou Q Y, et al. 2013. Discussion of seismogenic structure of the June 24, 2012 Ninglang-Yanyuan MS 5.7 earthquake. Seismology and Geology (in Chinese), 35(1): 37-49.
Chen X B, Cai J T, Wang L F, et al. 2014. Refined techniques for magnetotelluric data processing and two-dimensional inversion (Ⅳ): Statistical image method based on multi-site, multi-frequency tensor decomposition. Chinese Journal of Geophysics (in Chinese), 57(6): 1946-1957, doi: 10.6038/cjg20140625.
Chen X B, Ye T, Cai J T, et al. 2019. Refined techniques for data processing and two-dimensional inversion in magnetotelluric (Ⅶ): Electrical structure and seismogenic environment of Yingjiang-Longling seismic area. Chinese Journal of Geophysics (in Chinese), 62(4): 1377-1393, doi: 10.6038/cjg2019L0627.
Davey J, Roberts S, WilkinsonJ J. 2021. Copper-and cobalt-rich, ultrapotassic bittern brines responsible for the formation of the Nkana-Mindola deposits, Zambian Copperbelt. Geology, 49(3): 341-345. doi: 10.1130/G48176.1
Ding R, Ren J J, Zhang S M, et al. 2018. Late quaternary paleoearthquakes on the middle segment of the Lijiang-Xiaojinhe fault, Southeastern Tibet. Seismology and Geology (in Chinese), 40(3): 622-640.
Ding X P, Zhang H S, Feng Y L, et al. 2021. Geochemical characteristics and metallogenic mechanism of Miaoding coppergold deposit in Jinpingshan area, western Sichuan Province. Mineral Deposit (in Chinese), 40(1): 99-116.
Egbert G D. 1997. Robust multiple-station magnetotelluric data processing. Geophysical Journal International, 130(2): 475-496. doi: 10.1111/j.1365-246X.1997.tb05663.x
Egbert G D, Kelbert A. 2012. Computational recipes for electromagnetic inverse problems. Geophysical Journal International, 189(1): 251-267. doi: 10.1111/j.1365-246X.2011.05347.x
Gamble T D, Goubau W M, Clarke J. 1979. Magnetotellurics with a remote magnetic reference. Geophysics, 44(1): 53-68. doi: 10.1190/1.1440923
Hou Z Q, Zaw K, Pan G T, et al. 2007. Sanjiang Tethyan metallogenesis in S.W. China: Tectonic setting, metallogenic epochs and deposit types. Ore Geology Reviews, 31(1-4): 48-87. doi: 10.1016/j.oregeorev.2004.12.007
Huang Z X, Li H Y, Xu Y. 2013. Lithospheric S-wave velocity structure of the North-South Seismic Belt of China from surface wave tomography. Chinese Journal of Geophysics (in Chinese), 56(4): 1121-1131, doi: 10.6038/cjg20130408.
Li J S, Zheng M P, Jiang Z T, et al. 2013. Salt-and potash-forming analysis and forecast of the Yanyuan salt mine in Sichuan Province. Geology and Exploration (in Chinese), 49(4): 620-629.
Li J S, Zheng M P, Jiang Z T, et al. 2014. Water chemical characteristics of salt spring in Yanyuan of Sichuan province. Acta Geologica Sinica (in Chinese), 88(9): 1762-1770.
Li L, Chen Q F, Niu F L, et al. 2009. Slip rate along the Lijiang-Ninglang fault zone estimated from repeating microearthquakes. Chinese Science Bulletin, 54(3): 447-455.
Li X, Ma X B, Chen Y, et al. 2020. A plume-modified lithospheric barrier to the southeastward flow of partially molten Tibetan crust inferred from magnetotelluric data. Earth and Planetary Science Letters, 548: 116493, doi: 10.1016/j.epsl.2020.116493.
Li Y, Hou Z J, Si G Y, et al. 2001. Sedimentary characteristics and tectonic controls in Neogene Yanyuan tectonic escape basin in southeastern Qinghai-Tibet Plateau. Journal of Mineralogy and Petrology (in Chinese), 21(3): 34-43.
Liu Q Y, Van Der Hilst R D, Li Y, et al. 2014. Eastward expansion of the Tibetan Plateau by crustal flow and strain partitioning across faults. Nature Geoscience, 7(5): 361-365. doi: 10.1038/ngeo2130
Liu W Q, Wang X W, Liu H, et al. 2013. Application of velocity modeling and reverse time migration to subsalt structure. Chinese Journal of Geophysics (in Chinese), 56(2): 616-625, doi: 10.6038/cjg20130225.
Liu X X, Shao Z G. 2020. Current fault movement characteristics in the Lijiang-Xiaojinhe fault zone. Chinese Journal of Geophysics (in Chinese), 63(3): 1117-1126, doi: 10.6038/cjg2020N0228.
Liu Z Y, Chen X B, Cai J T, et al. 2017. A GUI client software for magnetotelluric's 3D inversion. //The Thirteenth China International Geo-Electromagnetic Workshop (in Chinese), 459-462.
Pan G T, Xu Y R, Wang P S. 1983. The Cenozoic tectonics at the eastern margin of Qinghai-Xizang Plateau. Contribution to the Geology of the Qinghai-Xizang (Tibet) Plateau (in Chinese). Beijing: Geological Publishing House, 129-141.
Pan G T, Xiao Q H, Lu S N, et al. 2009. Subdivision of tectonic units in China. Geology in China (in Chinese), 36(1): 1-28.
Qiao L, Yao H J, Lai Y C, et al. 2018. Crustal structure of southwest China and northern vietnam from ambient noise tomography: implication for the large-scale material transport model in SE Tibet. Tectonics, 37(5): 1492-1506. doi: 10.1029/2018TC004957
Tian Y, Qu C, Wang W T, et al. 2020. Characteristics of the ambient noise distribution recorded by the dense seismic array in the Yanyuan Basin. Chinese Journal of Geophysics (in Chinese), 63(6): 2248-2261, doi: 10.6038/cjg2020N0063.
Tong X Z, Liu J X, Li A Y. 2018. Two-dimensional regularized inversion of AMT data based on rotation invariant of Central impedance tensor. Earth and Planetary Physics, 2: 430-437.
Wang C Y, Lou H, Lv Z Y, et al. 2008. S-wave crustal and upper mantle's velocity structure in the eastern Tibetan Plateau-Deep environment of lower crustal flow. Science in China Series D: Earth Sciences, 51(2): 263-274. doi: 10.1007/s11430-008-0008-5
Wang F Y, Duan Y H, Yang Z X, et al. 2008. Velocity structure and active fault of Yanyuan-Mabian seismic zone-The result of high-resolution seismic refraction experiment. Science in China Series D: Earth Sciences, 51(9): 1284-1296. doi: 10.1007/s11430-008-0098-0
Wang W L, Wu J P, Fang L H, et al. 2017. Crustal thickness and Poisson's ratio in southwest China based on data from dense seismic arrays. Journal of Geophysical Research: Solid Earth, 122(9): 7219-7235. doi: 10.1002/2017JB013978
Wang X B, Yu N, Gao S, et al. 2017. Research progress in research on electrical structure of crust and upper mantle beneath the eastern margin of the Tibetan plateau. Chinese Journal of Geophysics (in Chinese), 60(6): 2350-2370, doi: 10.6038/cjg20170626.
Wang X S, Lv J, Xie Z J, et al. 2015. Focal mechanisms and tectonic stress field in the North-South Seismic Belt of China. Chinese Journal of Geophysics (in Chinese), 58(11): 4149-4162, doi: 10.6038/cjg20151122.
Xiang H F, Wei X X, Guo S M, et al. 2002. Sinistral thrusting along the Lijiang-Xiaojinhe fault since quaternary and its geologic-tectonic significance-Shielding effect of transverse structure of intracontinental active block. Seismology and Geology (in Chinese), 24(2): 188-198.
Xu S J, Shen W Z, Wang R C, et al. 1997. Characteristics and origin of Xifanping porphyry copper deposit, Yanyuan country, Sichuan province. Acta Mineralogica Sinica (in Chinese), 17(1): 56-62.
Xu X W, Wen X Z, Zheng R Z, et al. 2003. Pattern of latest tectonic motion and its dynamics for active blocks in Sichuan-Yunnan region, China. Science in China Series D: Earth Sciences, 46(S2): 210-226.
Xu X W, Wu X Y, Yu G H, et al. 2017. Seismo-geological signatures for identifying M ≥ 7.0 earthquake risk areas and their premilimary application in mainland China. Seismology and Geology (in Chinese), 39(2): 219-275.
Xu Y G, He B, Chung S L, et al. 2004. Geologic, geochemical, and geophysical consequences of plume involvement in the Emeishan flood-basalt province. Geology, 32(10): 917-920. doi: 10.1130/G20602.1
Xu Z Q, Li H B, Tang Z M, et al. 2011. The transformation of the terrain structures of the Tibet Plateau through large-scale strike-slip faults. Acta Petrologica Sinica (in Chinese), 27(11): 3157-3170.
Yang Y, Yao H J, Wu H X, et al. 2020. A new crustal shear-velocity model in Southwest China from joint seismological inversion and its implications for regional crustal dynamics. Geophysical Journal International, 220(2): 1379-1393.
Yao H J, Beghein C, Van Der Hilst R D. 2008. Surface wave array tomography in SE Tibet from ambient seismic noise and two-station analysis-Ⅱ. Crustal and upper-mantle structure. Geophysical Journal Interational, 173(1): 205-219. doi: 10.1111/j.1365-246X.2007.03696.x
Ye T, Chen X B, Yan L J. 2013. Refined techniques for data processing and two-dimensional inversion in magnetotelluric (Ⅲ): using the Impressing Method to construct starting model of 2D magnetotelluric inversion. Chinese Journal of Geophysics (in Chinese), 56(10): 3596-3606, doi: 10.6038/cjg20131034.
Zhan Y, Zhao G Z, Unsworth M, et al. 2013. Deep structure beneath the southwestern section of the Longmenshan fault zone and seimogenetic context of the 4.20 Lushan MS7.0 earthquake. Chinese Science Bulletin, 58(28): 3467-3474.
Zhang P Z. 2008. The tectonic deformation, strain distribution and deep dynamic processes in the eastern margin of the Qinghai-Tibetan plateau. Science in China Series D: Earth Sciences, 38(9): 1041-1056.
Zhang Z Q, Yao H J, Yang Y. 2020. Shear wave velocity structure of the crust and upper mantle in Southeastern Tibet and its geodynamic implications. Science China Earth Sciences, 63(9): 1278-1293. doi: 10.1007/s11430-020-9625-3
Zhao G Z, Unsworth M J, Zhan Y, et al. 2012. Crustal structure and rheology of the Longmenshan and Wenchuan MW7.9 earthquake epicentral area from magnetotelluric data. Geology, 40(12): 1139-1142. doi: 10.1130/G33703.1
Zheng C, Ding Z F, Song X D. 2016. Joint inversion of surface wave dispersion and receiver functions for crustal and uppermost mantle structure in Southeast Tibetan Plateau. Chinese Journal of Geophysics (in Chinese), 59(9): 3223-3236, doi: 10.6038/cjg20160908.
Zheng M P, Yuan H R, Zhang Y S, et al. 2010. Regional distribution and prospects of potash in China. Acta Geologica Sinica (in Chinese), 84(11): 1523-1553.
常祖峰, 杨盛用, 周青云等. 2013. 2012年6月24日宁蒗-盐源MS5.7地震发震构造刍议. 地震地质, 35(1): 37-49. doi: 10.3969/j.issn.0253-4967.2013.01.003
陈小斌, 蔡军涛, 王立凤等. 2014. 大地电磁资料精细处理和二维反演解释技术研究(四)——阻抗张量分解的多测点-多频点统计成像分析. 地球物理学报, 57(6): 1946-1957, doi: 10.6038/cjg20140625. http://www.geophy.cn/article/doi/10.6038/cjg20140625
陈小斌, 叶涛, 蔡军涛等. 2019. 大地电磁资料精细处理和二维反演解释技术研究(七)——云南盈江-龙陵地震区深部电性结构及孕震环境. 地球物理学报, 62(4): 1377-1393, doi: 10.6038/cjg2019L0627. http://www.geophy.cn/article/doi/10.6038/cjg2019L0627
丁锐, 任俊杰, 张世民等. 2018. 丽江-小金河断裂中段晚第四纪古地震历史. 地震地质, 40(3): 622-640. doi: 10.3969/j.issn.0253-4967.2018.03.009
丁晓平, 张辉善, 冯永来等. 2021. 川西锦屏山地区庙顶Cu-Au矿床地球化学特征与成矿机制探讨. 矿床地质, 40(1): 99-116. https://www.cnki.com.cn/Article/CJFDTOTAL-KCDZ202101007.htm
黄忠贤, 李红谊, 胥颐. 2013. 南北地震带岩石圈S波速度结构面波层析成像. 地球物理学报, 56(4): 1121-1131, doi: 10.6038/cjg20130408. http://www.geophy.cn/article/doi/10.6038/cjg20130408
李金锁, 郑绵平, 蒋忠惕等. 2013. 四川盐源盐矿成盐成钾分析预测. 地质与勘探, 49(4): 620-629. https://www.cnki.com.cn/Article/CJFDTOTAL-DZKT201304006.htm
李金锁, 郑绵平, 蒋忠惕等. 2014. 四川盐源盐泉水水化学特征分析. 地质学报, 88(9): 1762-1770. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE201409012.htm
李勇, 侯中健, 司光影等. 2001. 青藏高原东南缘晚第三纪盐源构造逸出盆地的沉积特征与构造控制. 矿物岩石, 21(3): 34-43. doi: 10.3969/j.issn.1001-6872.2001.03.006
刘文卿, 王西文, 刘洪等. 2013. 盐下构造速度建模与逆时偏移成像研究及应用. 地球物理学报, 56(2): 616-625, doi: 10.6038/cjg20130225. http://www.geophy.cn/article/doi/10.6038/cjg20130225
刘晓霞, 邵志刚. 2020. 丽江-小金河断裂带现今断层运动特征. 地球物理学报, 63(3): 1117-1126, doi: 10.6038/cjg2020N0228. http://www.geophy.cn/article/doi/10.6038/cjg2020N0228
刘钟尹, 陈小斌, 蔡军涛等. 2017. 一个大地电磁三维反演的可视化客户端软件. //第十三届中国国际地球电磁学术讨论会, 459-462.
潘桂棠, 徐耀荣, 王培生. 1983. 青藏高原东部边缘新生代构造. 青藏高原地质文集. 北京: 地质出版社, 129-141.
潘桂棠, 肖庆辉, 陆松年等. 2009. 中国大地构造单元划分. 中国地质, 36(1): 1-28. https://www.cnki.com.cn/Article/CJFDTOTAL-DIZI200901004.htm
田原, 瞿辰, 王伟涛等. 2020. 四川盐源盆地短周期密集台阵背景噪声分布特征分析. 地球物理学报, 63(6): 2248-2261, doi: 10.6038/cjg2020N0063. http://www.geophy.cn/article/doi/10.6038/cjg2020N0063
王椿镛, 楼海, 吕智勇等. 2008. 青藏高原东部地壳上地幔S波速度结构——下地壳流的深部环境. 中国科学D辑: 地球科学, 38(1): 22-32. doi: 10.3321/j.issn:1006-9267.2008.01.003
王绪本, 余年, 高嵩等. 2017. 青藏高原东缘地壳上地幔电性结构研究进展. 地球物理学报, 60(6): 2350-2370, doi: 10.6038/cjg20170626. http://www.geophy.cn/article/doi/10.6038/cjg20170626
王晓山, 吕坚, 谢祖军等. 2015. 南北地震带震源机制解与构造应力场特征. 地球物理学报, 58(11): 4149-4162, doi: 10.6038/cjg20151122. http://www.geophy.cn/article/doi/10.6038/cjg20151122
向宏发, 徐锡伟, 虢顺民等. 2002. 丽江-小金河断裂第四纪以来的左旋逆推运动及其构造地质意义——陆内活动地块横向构造的屏蔽作用. 地震地质, 24(2): 188-198. doi: 10.3969/j.issn.0253-4967.2002.02.006
徐士进, 沈渭洲, 王汝成等. 1997. 四川盐源西范坪斑岩铜矿特征和成因. 矿物学报, 17(1): 56-62. doi: 10.3321/j.issn:1000-4734.1997.01.009
徐锡伟, 闻学泽, 郑荣章等. 2003. 川滇地区活动块体最新构造变动样式及其动力来源. 中国科学(D辑), 33(S1): 151-162. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK2003S1016.htm
徐锡伟, 吴熙彦, 于贵华等. 2017. 中国大陆高震级地震危险区判定的地震地质学标志及其应用. 地震地质, 39(2): 219-275. doi: 10.3969/j.issn.0253-4967.2017.02.001
许志琴, 李海兵, 唐哲民等. 2011. 大型走滑断裂对青藏高原地体构架的改造. 岩石学报, 27(11): 3157-3170. https://www.cnki.com.cn/Article/CJFDTOTAL-YSXB201111001.htm
叶涛, 陈小斌, 严良俊. 2013. 大地电磁资料精细处理和二维反演解释技术研究(三)——构建二维反演初始模型的印模法. 地球物理学报, 56(10): 3596-3606, doi: 10.6038/cjg20131034. http://www.geophy.cn/article/doi/10.6038/cjg20131034
詹艳, 赵国泽, Unsworth M等. 2013. 龙门山断裂带西南段4.20芦山7.0级地震区的深部结构和孕震环境. 科学通报, 58(20): 1917-1924. https://www.cnki.com.cn/Article/CJFDTOTAL-KXTB201320006.htm
张培震. 2008. 青藏高原东缘川西地区的现今构造变形、应变分配与深部动力过程. 中国科学D辑: 地球科学, 38(9): 1041-1056. doi: 10.3321/j.issn:1006-9267.2008.09.001
张智奇, 姚华建, 杨妍. 2020. 青藏高原东南缘地壳上地幔三维S波速度结构及动力学意义. 中国科学: 地球科学, 50(9): 1242-1258. https://www.cnki.com.cn/Article/CJFDTOTAL-JDXK202009007.htm
郑晨, 丁志峰, 宋晓东. 2016. 利用面波频散与接收函数联合反演青藏高原东南缘地壳上地幔速度结构. 地球物理学报, 59(9): 3223-3236, doi: 10.6038/cjg20160908. http://www.geophy.cn/article/doi/10.6038/cjg20160908
郑绵平, 袁鹤然, 张永生等. 2010. 中国钾盐区域分布与找钾远景. 地质学报, 84(11): 1523-1523. https://www.cnki.com.cn/Article/CJFDTOTAL-DZXE201011002.htm
-
下载:
图(9)
计量
- 文章访问数:
- PDF下载数:
- 施引文献: 0