Lithosphere Anisotropy of Prydz Bay, Antarctica: From Ocean Bottom Seismometer Long Term Observation
-
摘要: 为了研究南极普里兹湾岩石圈深部应力场及其动力学，采用S波分裂旋转相关法，对中国第31次南极科学考察成功回收的3个站位海底地震仪数据(5个远震记录)进行了反演，获得了普里兹湾洋陆过渡带岩石圈各向异性特征.结果表明，台站所在区域各向异性显著，在较小的范围内存在明显的空间差异，快S波偏振方向变化范围是N40°E ~ N60°E，快慢波时间延迟变化范围为0.2~1.3 s.洋盆的各向异性主要取决于海底扩张地幔流作用，大陆及附近的各向异性主要受上地幔顶部残留构造的影响，而中间过渡带各向异性层厚度较小集中在地壳内，它可能受海底扩张地幔流和残留构造共同作用.Abstract: In order to understand better the stress field and dynamics characteristic of the lithosphere at Prydz bay in the Antarctica, rotation-correlation shear wave splitting method is used to study 5 earthquakes recorded by three ocean bottom seismometers recovered at Prydz bay during the 31th Chinese Antarctic Research Expedition to obtain the anisotropy characteristics of the continent and ocean transition of Prydz bay in this paper. Our inversion results show strong anisotropy in the lithosphere of Prydz bay with spatial differences in small scale. The fast shear wave polarization directions are from N40°E to N60°E, fast and slow shear wave times delay are from 0.2 s to 1.3 s. We think that the anisotropy at the oceanic part is dominated by the mantle flow of mid-ocean ridge spreading, while the continental part is dominated by the relic structural fabric of the ancient lithosphere at the top of the upper mantle, and the middle zone with shallower and thinner anisotropy layer may be influenced by the both reasons above.
-
Key words:
- Prydz bay /
- anisotropy /
- shear wave splitting /
- ocean bottom seismometer /
- marine geology
-
图 1 (a)研究区在全球的位置和地震震中分布，(b)OBS站位分布
SEIR的扩张方向为NE-SW向(Baran et al., 2005)
Fig. 1. (a) The location of study area and the positions of earthquake hypocenters, (b) positions of OBSs for long term earthquake observation
图 3 OBS1站位事件2的S波分裂反演结果及分析
a.旋转相关计算前的快慢波波形；b.旋转相关计算后的快慢波波形；c.旋转相关计算前的质点运动轨迹；d.旋转相关计算后的质点运动轨迹；e.反演结果，横轴δt为时间延迟，纵轴φ为偏振方向，两个极值点分别代表快波(δt＞0) 和慢波(δt＜0) 的结果，极值点对应的纵轴值分别为快波和慢波的偏振方向，横轴值分别为快慢波的时间延迟.如e图中快慢波的时间延迟为0.9 s，快波方向为N42°E，慢波方向为N138°E
Fig. 3. S wave splitting inversion results and analysis for earthquake No. 2 recorded by OBS1
图 4 OBS1站位事件3的S波分裂反演结果及分析
相关说明同图 3；e图中的快慢波时间延迟为0.8 s，快S波偏振方向为N40°E
Fig. 4. S wave splitting inversion results and analysis for earthquake No. 3 recorded by OBS1
图 5 OBS2站位事件2的S波分裂反演结果及分析
相关说明同图 3；e图中的快慢波时间延迟为0.4 s，快S波偏振方向为N44°E
Fig. 5. S wave splitting inversion results and analysis for earthquake No. 2 recorded by OBS2
图 6 OBS5站位事件2的S波分裂反演结果及分析
相关说明同图 3；e图中的快慢波时间延迟为0.2 s，快S波偏振方向为N56°E
Fig. 6. S wave splitting inversion results and analysis for earthquake No. 2 recorded by OBS5
图 7 普里兹湾区域S波分裂反演得到的快波方向和时间延迟
陆地台站的信息来源于Reading and Heintz(2008)
Fig. 7. S wave splitting inversion results of fast wave polarization directions and the times delay between fast and slow waves at Prydz bay
表 1 地震事件与S波分裂反演结果
Table 1. Earthquake events and S wave splitting inversion results
地震事件编号 发震时间
(格林威治时间)纬度(°) 经度(°) 震源深度(km) 地震震级(Ms) OBS1 OBS2 OBS5 d1 φ1 t1 d2 φ2 t2 d5 φ5 t5 1 2013-04-06
T04:42:35.860Z-3.517 138.476 66.0 7.0 77.314 - - 77.200 44 0.2 77.795 52 0.5 2 2013-05-23
T17:19:04.750Z-23.009 -177.232 173.7 7.4 76.884 42 0.9 76.683 44 0.4 76.046 56 0.2 3 2013-06-05
T04:47:26.240Z-11.401 166.299 39.0 6.1 81.023 40 0.8 80.989 - - 80.840 - - 4 2013-06-16
T02:51:35.750Z-56.280 -27.443 91.2 5.5 44.287 40 1.3 43.947 - - 42.998 - - 5 2013-07-15
T14:03:39.880Z-60.857 -25.070 11.0 7.3 39.879 - - 39.521 - - 38.522 60 0.8 注：d1，d2，d5分别代表OBS1，OBS2和OBS5对某一地震事件的震中距，单位为°；φ1，φ2，φ5分别代表OBS1，OBS2和OBS5对某一地震事件的快波方位角，单位为°；t1，t2，t5分别代表OBS1，OBS2和OBS5对某一地震事件的快慢波时间延迟，单位为s；“-”为未记录或未得到结果. 
下载: 导出CSV
-
Baran, J.M., Cochran, J.R., Carbotte, S.M., et al., 2005.Variations in Upper Crustal Structure due to Variable Mantle Temperature along the Southeast Indian Ridge.Geochemistry Geophysics Geosystems, 6(11):292-309.doi: 10.1029/2005GC000943 Boger, S.D., Wilson, C.J.L., 2003.Brittle Faulting in the Prince Charles Mountains, East Antarctica:Cretaceous Transtensional Tectonics Related to the Break-up of Gondwana.Tectonophysics, 367:173-186. doi: 10.1016/S0040-1951(03)00125-2 Bowman, J.R., Ando, M., 1987.Shear-Wave Splitting in the Upper-Mantle Wedge above the Tonga Subduction Zone.Geophysical Journal International, 88(1):25-41.doi: 10.1111/j.1365-246x.1987.tb01367.x Chen, T.Y., Shen, Y.B., Zhao, Y., et al., 2008.Geological Development of Antarctica and Evolution of Gondwanaland.The Commercial Press, Beijing (in Chinese). Christensen, N.L., 1984.The Magnitude, Symmetry and Origin of Upper Mantle Anisotropy Based on Fabric Analyses of Ultramafic Tectonites.Geophysical Journal International, 76(1):89-111.doi: 10.1111/j.1365-246x.1984.tb05025.x Conrad, C.P., Behn, M.D., Silver, P.G., 2007.Global Mantle Flow and the Development of Seismic Anisotropy:Differences between the Oceanic and Continental upper Mantle.J.Geophys.Res., 112:B07317.doi: 10.1029/2006JB004608 Crampin, S., 1977.A Review of the Effects of Anisotropic Layering on the Propagation of Seismic Waves.Geophysical Journal International, 49(1):9-27.doi: 10.1111/j.1365-246x.1977.tb03698.x Cui, P., Wang, J.H., Li, B., 2010.Research of Design Method for Ocean Bottom Seismometer Based on the Coupling Theory.Ship Science and Technology, 32(4):89-92 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTotal-JCKX201004027.htm Debayle, E., Kennett, B.L.N., 2000.Anisotropy in the Australasian Upper Mantle from Love and Rayleigh Waveform Inversion.Earth and Planetary Science Letters, 184(1):339-351.doi: 10.1016/s0012-821x(00)00314-9 Ding, W.W., Dong, C.Z., Cheng, Z.H., 2013.Sedimentary Characteristics and Hydrocarbon Potential in the Prydz Bay, East Antarctica.Earth Science, 38(1):103-112(in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTotal-DQKX2013S1013.htm Dong, C.Z., Ding, W.W., Li, J.B., et al., 2013.The Gravity and Magnetic Anomally and Crustal Structure of Prydz Bay, East Antarctica.Chinese Journal of Geophysics, 56(10):3346-3360(in Chinese with English abstract).doi: 10.6038/cjg20131011 Fouch, M.J., Rondenay, S., 2006.Seismic Anisotropy beneath Stable Continental Interiors.Physics of the Earth and Planetary Interiors, 158(2-4):292-320.doi: 10.1016/j.pepi.2006.03.024 Huang, Z.C., 2011.A Seismological Study of Structure and Dynamics in the Earth:Mainland China and Northeast Japan as Examples(Dissertation).Nanjing University, Nanjing (in Chinese with English abstract). Keith, C.M., Crampin, S., 1977.Seismic Body Waves in Anisotropic Media:Synthetic Seismograms.Geophysical Journal International, 49(1):225-243.doi: 10.1111/j.1365-246x.1977.tb03710.x Kubo, A., Hiramatsu, Y., Kanao, M., et al., 1995.An Analysis of the SKS Splitting at Syowa Station in Antarctica Geosciences.Proc.NIPR Symp.Antarct.Geosci., 8:25-34. http://ci.nii.ac.jp/naid/110001071775 Kubo, A., Kanao, M., 1997.Crust-Mantle Decoupling Revealed by Seismic Velocity Anisotropy beneath Syowa Station, Antarctica.Antarctic Record, 41(2):497-512 (in Japanese). http://ci.nii.ac.jp/naid/110000206101 Long, M.D., Becker, T.W., 2010.Mantle Dynamics and Seismic Anisotropy.Earth & Planetary Science Letters, 297(3):341-354. http://www.sciencedirect.com/science/article/pii/S0012821X10004115 Müller, C., 2001.Upper Mantle Seismic Anisotropy beneath Antarctica and the Scotia Sea Region.Geophysical Journal International, 147(1):105-122. doi: 10.1046/j.1365-246X.2001.00517.x Raitt, R.W., Shor, G.G., Francis, T.J.G., et al., 1969.Anisotropy of the Pacific Upper Mantle.Journal of Geophysical Research, 74(12):3095-3109.doi: 10.1029/jb074i012p03095 Reading, A.M., Heintz, M., 2008.Seismic Anisotropy of East Antarctica from Shear-Wave Splitting:Spatially Varying Contributions from Lithospheric Structural Fabric and Mantle Flow? Earth & Planetary Science Letters, 268(3-4):433-443. http://www.sciencedirect.com/science/article/pii/S0012821X08000678 Ruan, A.G., Li, J.B., Chen, Y.S., et al., 2010.The Experiment of Broad Band Ⅰ-4C Type OBS in the Southwest Indian Ridge.Chinese Journal of Geophysics, 53(4):1015-1018 (in Chinese with English abstract).doi: 10.3969/j.issn.0001-5733.2010.04.026 Ruan, A.G., Li, J.B., Lee, C.S., et al., 2012.Passive Seismic Experiment and ScS Wave Splitting in the Southwestern Sub-Basin of South China Sea.Chinese Science Bulletin, 57(25):3381-3390.doi: 10.1007/s11434.012.5132.0 Silver, P.G., Chan, W.W., 1991.Shear Wave Splitting and Subcontinental Mantle Deformation.Journal of Geophysical Research Atmospheres, 96(B10):16429-16454. doi: 10.1029/91JB00899 Stagg, H.M.J., 1985.The Structure and Origin of Prydz Bay and the Mac.Robertson Shelf, East Antarctica.Tectonophysics, 114:315-340. doi: 10.1016/0040-1951(85)90019-8 Stagg, H.M.J., Colwel, J.B., Direen, N.G., et al., 2004.Geology of the Continental Margin of Enderby and Mac.Robertson Lands, East Antarctica:Insights from a Regional Data Set.Marine Geophysical Researches, 25:183-219. doi: 10.1007/s11001-005-1316-1 Steven, D.B., 2011.Antarctica-before and after Gondwana.Gondwana Research, 19:335-371. doi: 10.1016/j.gr.2010.09.003 Tian, B.F., Yang, J.S., Liu, S., et al., 2012.Progress of Seismological Research in Antarctica Region.Acta Seismologica Sinica, 34(2):267-279 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DZXB201202013.htm Zhang, L., Zhao, M.H., Wang, J., et al., 2013.Correction of OBS Position and Recent Advances of 3D Seismic Exploration in the Central Sub-Basin of South China Sea.Earth Science, 38(1):33-42 (in Chinese with English abstract). http://en.cnki.com.cn/Article_en/CJFDTOTAL-DQKX201301008.htm Zhao, Y., Liu, X.C., Song, B., et al., 1995.Constraints on the Stratigraphic Age of Metasedimentary Rocks of the Larsemann Hills, East Antarctica:Possible Implication for Neo-Pro-Terozoic Tectonics.Precambrian Research, 75:175-188. doi: 10.1016/0301-9268(95)80005-3 陈廷愚, 沈炎彬, 赵越, 等, 2008. 南极洲地质发展与冈瓦纳古陆演化. 北京: 商务印书馆. 崔培, 王纪会, 李彪, 2010.基于耦合理论的海底地震仪设计方法研究.舰船科学技术, 32(4):89-92. http://www.cnki.com.cn/Article/CJFDTOTAL-JCKX201004027.htm 丁巍伟, 董崇志, 程子华, 2013.南极洲东部普里兹湾区沉积特征及油气资源潜力.地球科学, 38(1):103-112. http://kns.cnki.net/KCMS/detail/detail.aspx?filename=dqkx2013s1013&dbname=CJFD&dbcode=CJFQ 董崇志, 丁巍伟, 李家彪, 等, 2013.南极洲东部普里兹湾海域重磁场特征及地壳结构.地球物理学报, 56(10):3346-3360. doi: 10.6038/cjg20131011 黄周传, 2011. 利用天然地震研究地球内部结构与动力学: 以中国大陆和东北日本为例(博士学位论文). 南京: 南京大学. http://cdmd.cnki.com.cn/Article/CDMD-10284-1011127128.htm 阮爱国, 李家彪, 陈永顺, 等, 2010.国产Ⅰ-4C型OBS在西南印度洋中脊的试验.地球物理学报, 53(4):1015-1018. http://www.cnki.com.cn/Article/CJFDTOTAL-DQWX201004027.htm 田宝峰, 杨建思, 刘莎, 等, 2012.南极地震学研究进展.地震学报, 34(2):267-279. http://www.cnki.com.cn/Article/CJFDTOTAL-DZXB201202013.htm 张莉, 赵明辉, 王建, 等, 2013.南海中央次海盆OBS位置校正及三维地震探测新进展.地球科学, 38(1):33-42. http://earth-science.net/WebPage/Article.aspx?id=2342 -
点击查看大图
计量
- 文章访问数: 5647
- HTML全文浏览量: 2155
- PDF下载量: 24
- 被引次数: 0
