Investigating the D" Reflector Beneath the Indian Ocean with Source Arrays
DOI:
https://doi.org/10.26443/seismica.v4i2.1418Keywords:
lower mantle, array seismic methdos, source arrays, DAbstract
We used seismic P-wave reflections to search for the discontinuity at the top of the D" region beneath the Indian Ocean. Due to a lack of seismic receiver arrays to target this region, we build source arrays using earthquakes in Indonesia and taking advantage of the long-running history of GEOSCOPE stations located in the western Indian Ocean and Antarctica, as well as three additional stations (Seychelles and Antarctica). Despite restricting the earthquake depth range, source-array stacks were difficult to interpret due to complications arising from differing earthquake depths, violating the plane wave assumption. Therefore, we use a source-array scatter imaging method, that does not rely on travel-times calculated for a plane wave. Using this technique in conjunction with source normalization, we found evidence for a D" P-wave reflector for several stations with reflector depths varying between 230-160 km above the CMB South of Australia and 190 to 270 km above the CMB beneath the Indian Ocean, where the depth of the reflector in the north of our study area is consistent with previously imaged D" depths using S-waves and agrees with receiver array data. We suggest that earlier imaged subducted lithosphere in this region is responsible for our D" reflections.References
Barruol, G., & Sigloch, K. (2013). Investigating La Réunion Hot Spot From Crust to Core. Eos, Transactions American Geophysical Union, 94(23), 205–207. https://doi.org/10.1002/2013eo230002
Bullen, K. E. (1950). An earth model based on a compressibility pressure hypothesis. Geophysical Journal International, 6, 50–59. https://doi.org/10.1111/j.1365-246x.1950.tb02973.x
Cobden, L., Thomas, C., & Trampert, J. (2015). Seismic Detection of Post-perovskite Inside the Earth. In The Earth’s Heterogeneous Mantle (pp. 391–440). Springer International Publishing. https://doi.org/10.1007/978-3-319-15627-9_13
Creasy, N., Long, M. D., & Ford, H. A. (2017). Deformation in the lowermost mantle beneath Australia from observations and models of seismic anisotropy. Journal of Geophysical Research: Solid Earth, 122(7), 5243–5267. https://doi.org/10.1002/2016jb013901
Douet, V., Vallée, M., Zigone, D., Bonaimé, S., Stutzmann, E., Maggi, A., Pardo, C., Bernard, A., Leroy, N., Pesqueira, F., Lévêque, J.-J., Thoré, J.-Y., Berc, M. B., & Sayadi, J. (2016). The GEOSCOPE broadband seismic observatory. EGU General Assembly, 18, 2016–8867.
Florez, M. A., & Prieto, G. A. (2017). Precise relative earthquake depth determination using array processing techniques. Journal of Geophysical Research: Solid Earth, 122(6), 4559–4571. https://doi.org/10.1002/2017jb014132
Garnero, E. J., McNamara, A. K., & Shim, S.-H. (2016). Continent-sized anomalous zones with low seismic velocity at the base of Earth’s mantle. Nature Geoscience, 9(7), 481–489. https://doi.org/10.1038/ngeo2733
Greff-Lefftz, M., Métivier, L., Panet, I., Caron, L., Pajot-Métivier, G., & Bouman, J. (2016). Joint analysis of GOCE gravity gradients data of gravitational potential and of gravity with seismological and geodynamic observations to infer mantle properties. Geophysical Journal International, 205(1), 257–283. https://doi.org/10.1093/gji/ggw002
Gubbins, D., Willis, A. P., & Sreenivasan, B. (2007). Correlation of Earth’s magnetic field with lower mantle thermal and seismic structure. Physics of the Earth and Planetary Interiors, 162(3–4), 256–260. https://doi.org/10.1016/j.pepi.2007.04.014
Haddon, R. A. W., & Cleary, J. R. (1974). Evidence for scattering of seismic PKP waves near the mantle-core boundary. Physics of the Earth and Planetary Interiors, 8(3), 211–234. https://doi.org/10.1016/0031-9201(74)90088-0
Hedlin, M. A. H., & Shearer, P. M. (2000). An analysis of large‐scale variations in small‐scale mantle heterogeneity using Global Seismographic Network recordings of precursors to PKP. Journal of Geophysical Research: Solid Earth, 105(B6), 13655–13673. https://doi.org/10.1029/2000jb900019
Heyn, B., & Thomas, C. (2025). Investigating the D" Reflector Beneath the Indian Ocean with Source Arrays. Zenodo. https://doi.org/10.5281/ZENODO.15426460
Hosseini, K., Matthews, K. J., Sigloch, K., Shephard, G. E., Domeier, M., & Tsekhmistrenko, M. (2018). SubMachine: Web‐Based Tools for Exploring Seismic Tomography and Other Models of Earth’s Deep Interior. Geochemistry, Geophysics, Geosystems, 19(5), 1464–1483. https://doi.org/10.1029/2018gc007431
Hutko, A. R., Lay, T., & Revenaugh, J. (2009). Localized double-array stacking analysis of PcP: D″ and ULVZ structure beneath the Cocos plate, Mexico, central Pacific, and north Pacific. Physics of the Earth and Planetary Interiors, 173(1–2), 60–74. https://doi.org/10.1016/j.pepi.2008.11.003
Institut de physique du globe de Paris (IPGP), & École et Observatoire des Sciences de la Terre de Strasbourg (EOST). (1982). GEOSCOPE, French Global Network of broad band seismic stations. Institut de physique du globe de Paris (IPGP), Université de Paris. https://doi.org/10.18715/GEOSCOPE.G
Jackson, A., Jonkers, A. R. T., & Walker, M. R. (2000). Four centuries of geomagnetic secular variation from historical records. Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences, 358(1768), 957–990. https://doi.org/10.1098/rsta.2000.0569
Jackson, J. M., & Thomas, C. (2021). Seismic and Mineral Physics Constraints on the D″ Layer. In Mantle Convection and Surface Expressions (pp. 193–227). Wiley. https://doi.org/10.1002/9781119528609.ch8
Kendall, J. ‐M., & Shearer, P. M. (1994). Lateral variations in D″ thickness from long‐period shear wave data. Journal of Geophysical Research: Solid Earth, 99(B6), 11575–11590. https://doi.org/10.1029/94jb00236
Kendall, J.-M., & Shearer, P. M. (1995). On the structure of the lowermost mantle beneath the southwest Pacific, southeast Asia and Australasia. Physics of the Earth and Planetary Interiors, 92(1–2), 85–98. https://doi.org/10.1016/0031-9201(95)03063-3
Kennett, B. L. N., Engdahl, E. R., & Buland, R. (1995). Constraints on seismic velocities in the Earth from traveltimes. Geophysical Journal International, 122(1), 108–124. https://doi.org/10.1111/j.1365-246x.1995.tb03540.x
Kito, T., & Krüger, F. (2001). Heterogeneities in D” beneath the southwestern Pacific inferred from scattered and reflected P‐waves. Geophysical Research Letters, 28(13), 2545–2548. https://doi.org/10.1029/2000gl012801
Kito, T., Krüger, F., & Negishi, H. (2004). Seismic heterogeneous structure in the lowermost mantle beneath the southwestern Pacific. Journal of Geophysical Research: Solid Earth, 109(B9). https://doi.org/10.1029/2003jb002677
Kito, T., Rost, S., Thomas, C., & Garnero, E. J. (2007). New insights into the P-and S-wave velocity structure of the D′′ discontinuity beneath the Cocos plate. Geophysical Journal International, 169(2), 631–645. https://doi.org/10.1111/j.1365-246x.2007.03350.x
Koelemeijer, P. (2021). Toward Consistent Seismological Models of the Core–Mantle Boundary Landscape. In Mantle Convection and Surface Expressions (pp. 229–255). Wiley. https://doi.org/10.1002/9781119528609.ch9
Koroni, M., & Trampert, J. (2015). The effect of topography of upper mantle discontinuities on SS precursors. Geophysical Journal International, 204(1), 667–681. https://doi.org/10.1093/gji/ggv471
Krüger, F., Scherbaum, F., Weber, M., & Schlittenhardt, J. (1996). Analysis of asymmetric multipathing with a generalization of the double-beam method. Bulletin of the Seismological Society of America, 86(3), 737–749. https://doi.org/10.1785/bssa0860030737
Krüger, F., Weber, M., Scherbaum, F., & Schlittenhardt, J. (1995). Evidence for normal and inhomogeneous lowermost mantle and core-mantle boundary structure under the Arctic and northern Canada. Geophysical Journal International, 122(2), 637–657. https://doi.org/10.1111/j.1365-246x.1995.tb07017.x
Lay, T. (2015). Deep Earth Structure: Lower Mantle and D″. In Treatise on Geophysics (pp. 683–723). Elsevier. https://doi.org/10.1016/b978-0-444-53802-4.00019-1
Lay, T., Berger, J., Buland, R., Butler, R., Ekström, G., Hutt, C. R., & Romanowicz, B. (2002). Global Seismic Network Design Goals Update 2002. IRIS.
Lay, T., Garnero, E. J., & Russell, S. A. (2004). Lateral variation of the D″ discontinuity beneath the Cocos Plate. Geophysical Research Letters, 31(15). https://doi.org/10.1029/2004gl020300
Lay, T., & Helmberger, D. V. (1983). A lower mantle S-wave triplication and the shear velocity structure of D". Geophysical Journal International, 75(3), 799–837. https://doi.org/10.1111/j.1365-246x.1983.tb05010.x
Lessing, S., Thomas, C., Saki, M., Schmerr, N., & Vanacore, E. (2015). On the difficulties of detecting PP precursors. Geophysical Journal International, 201(3), 1666–1681. https://doi.org/10.1093/gji/ggv105
Ligorría, J. P., & Ammon, C. J. (1999). Iterative deconvolution and receiver-function estimation. Bulletin of the Seismological Society of America, 89(5), 1395–1400. https://doi.org/10.1785/bssa0890051395
Mancinelli, N., Shearer, P., & Thomas, C. (2016). On the frequency dependence and spatial coherence of PKP precursor amplitudes. Journal of Geophysical Research: Solid Earth, 121(3), 1873–1889. https://doi.org/10.1002/2015jb012768
McNamara, A. K. (2019). A review of large low shear velocity provinces and ultra low velocity zones. Tectonophysics, 760, 199–220. https://doi.org/10.1016/j.tecto.2018.04.015
Müller, G. (1985). The reflectivity method: a tutorial. Journal of Geophysics, 58(1), 153–174.
Pisconti, A., Creasy, N., Wookey, J., Long, M. D., & Thomas, C. (2022). Mineralogy, fabric and deformation domains in D″ across the southwestern border of the African LLSVP. Geophysical Journal International, 232(1), 705–724. https://doi.org/10.1093/gji/ggac359
Pisconti, A., Thomas, C., & Wookey, J. (2019). Discriminating Between Causes of D″ Anisotropy Using Reflections and Splitting Measurements for a Single Path. Journal of Geophysical Research: Solid Earth, 124(5), 4811–4830. https://doi.org/10.1029/2018jb016993
Rao, P. B., Ravi Kumar, M., & Singh, A. (2017). Anisotropy in the lowermost mantle beneath the Indian Ocean Geoid Low from ScS splitting measurements. Geochemistry, Geophysics, Geosystems, 18(2), 558–570. https://doi.org/10.1002/2016gc006604
Reasoner, C., & Revenaugh, J. (1999). Short‐period P wave constraints on D″ reflectivity. Journal of Geophysical Research: Solid Earth, 104(B1), 955–961. https://doi.org/10.1029/1998jb900053
Reiss, A., Thomas, C., van Driel, J., & Heyn, B. (2017). A hot midmantle anomaly in the area of the Indian Ocean Geoid Low. Geophysical Research Letters, 44(13), 6702–6711. https://doi.org/10.1002/2017gl073440
Ringler, A. T., Anthony, R. E., Aster, R. C., Ammon, C. J., Arrowsmith, S., Benz, H., Ebeling, C., Frassetto, A., Kim, W. ‐Y., Koelemeijer, P., Lau, H. C. P., Lekić, V., Montagner, J. P., Richards, P. G., Schaff, D. P., Vallée, M., & Yeck, W. (2022). Achievements and Prospects of Global Broadband Seismographic Networks After 30 Years of Continuous Geophysical Observations. Reviews of Geophysics, 60(3). https://doi.org/10.1029/2021rg000749
Ritsema, J., Deuss, A., van Heijst, H. J., & Woodhouse, J. H. (2010). S40RTS: a degree-40 shear-velocity model for the mantle from new Rayleigh wave dispersion, teleseismic travel time and normal-mode splitting function measurements. Geophysical Journal International, 184(3), 1223–1236. https://doi.org/10.1111/j.1365-246x.2010.04884.x
Romanowicz, B., Cara, M., Fel, J. F., & Rouland, D. (1984). GEOSCOPE: A French initiative in long‐period three‐component global seismic networks. Eos, Transactions American Geophysical Union, 65(42), 753–753. https://doi.org/10.1029/eo065i042p00753-01
Rost, S., & Thomas, C. (2002). ARRAY SEISMOLOGY: METHODS AND APPLICATIONS. Reviews of Geophysics, 40(3). https://doi.org/10.1029/2000rg000100
Rost, S., & Thomas, C. (2009). Improving Seismic Resolution Through Array Processing Techniques. Surveys in Geophysics, 30(4–5), 271–299. https://doi.org/10.1007/s10712-009-9070-6
Roult, G., Montagner, J. P., Romanowicz, B., Cara, M., Rouland, D., Pillet, R., Karczewski, J. F., Rivera, L., Stutzmann, E., & Maggi, A. (2010). The GEOSCOPE Program: Progress and Challenges during the Past 30 Years. Seismological Research Letters, 81(3), 427–452. https://doi.org/10.1785/gssrl.81.3.427
Scherbaum, F., Krüger, F., & Weber, M. (1997). Double beam imaging: Mapping lower mantle heterogeneities using combinations of source and receiver arrays. Journal of Geophysical Research: Solid Earth, 102(B1), 507–522. https://doi.org/10.1029/96jb03115
Schweitzer, J., Fyen, J., Mykkeltveit, S., & Kvaerna, T. (2009). 9. Seismic Arrays. In P. Bormann (Ed.), New Manual of Seismological Observatory Practice (NMSOP) (pp. 1–52). Deutsches GeoForschungsZentrum GFZ. https://doi.org/10.2312/GFZ.NMSOP_R1_CH9
Shephard, G. E., Matthews, K. J., Hosseini, K., & Domeier, M. (2017). On the consistency of seismically imaged lower mantle slabs. Scientific Reports, 7(1). https://doi.org/10.1038/s41598-017-11039-w
Simmons, N. A., Myers, S. C., Johannesson, G., Matzel, E., & Grand, S. P. (2015). Evidence for long‐lived subduction of an ancient tectonic plate beneath the southern Indian Ocean. Geophysical Research Letters, 42(21), 9270–9278. https://doi.org/10.1002/2015gl066237
Spasojevic, S., Gurnis, M., & Sutherland, R. (2010). Mantle upwellings above slab graveyards linked to the global geoid lows. Nature Geoscience, 3(6), 435–438. https://doi.org/10.1038/ngeo855
Stähler, S. C., Khan, A., Banerdt, W. B., Lognonné, P., Giardini, D., Ceylan, S., Drilleau, M., Duran, A. C., Garcia, R. F., Huang, Q., Kim, D., Lekic, V., Samuel, H., Schimmel, M., Schmerr, N., Sollberger, D., Stutzmann, È., Xu, Z., Antonangeli, D., … Smrekar, S. E. (2021). Seismic detection of the martian core. Science, 373(6553), 443–448. https://doi.org/10.1126/science.abi7730
Stammler, K. (1993). Seismichandler—Programmable multichannel data handler for interactive and automatic processing of seismological analyses. Computers & Geosciences, 19(2), 135–140. https://doi.org/10.1016/0098-3004(93)90110-q
Thomas, C., Weber, M., Wicks, C. W., & Scherbaum, F. (1999). Small scatterers in the lower mantle observed at German broadband arrays. Journal of Geophysical Research: Solid Earth, 104(B7), 15073–15088. https://doi.org/10.1029/1999jb900128
Thomas, Ch., Kendall, J.-M., & Weber, M. (2002). The lowermost mantle beneath northern Asia-I. Multi-azimuth studies of a D″ heterogeneity. Geophysical Journal International, 151(1), 279–295. https://doi.org/10.1046/j.1365-246x.2002.01759.x
Thomas, Ch., & Weber, M. (1997). P velocity heterogeneities in the lower mantle determined with the German Regional Seismic Network: improvement of previous models and results of 2D modelling. Physics of the Earth and Planetary Interiors, 101(1–2), 105–117. https://doi.org/10.1016/s0031-9201(96)03245-1
Thomas, Christine, Garnero, E. J., & Lay, T. (2004). High‐resolution imaging of lowermost mantle structure under the Cocos plate. Journal of Geophysical Research: Solid Earth, 109(B8). https://doi.org/10.1029/2004jb003013
Thomas, Christine, Kendall, J.-M., & Lowman, J. (2004). Lower-mantle seismic discontinuities and the thermal morphology of subducted slabs. Earth and Planetary Science Letters, 225(1–2), 105–113. https://doi.org/10.1016/j.epsl.2004.05.038
Thomas, Christine, Wookey, J., Brodholt, J., & Fieseler, T. (2011). Anisotropy as cause for polarity reversals of D″ reflections. Earth and Planetary Science Letters, 307(3–4), 369–376. https://doi.org/10.1016/j.epsl.2011.05.011
Tsekhmistrenko, M., Sigloch, K., Hosseini, K., & Barruol, G. (2021). A tree of Indo-African mantle plumes imaged by seismic tomography. Nature Geoscience, 14(8), 612–619. https://doi.org/10.1038/s41561-021-00762-9
Usui, Y., Hiramatsu, Y., Furumoto, M., & Kanao, M. (2008). Evidence of seismic anisotropy and a lower temperature condition in the D″ layer beneath Pacific Antarctic Ridge in the Antarctic Ocean. Physics of the Earth and Planetary Interiors, 167(3–4), 205–216. https://doi.org/10.1016/j.pepi.2008.04.006
Weber, M. (1993). P- and S-wave reflections from anomalies in the lowermost mantle. Geophysical Journal International, 115(1), 183–210. https://doi.org/10.1111/j.1365-246x.1993.tb05598.x
Weber, M., & Davis, J. P. (1990). Evidence of a laterally variable lower mantle structure from P- and S-waves. Geophysical Journal International, 102(1), 231–255. https://doi.org/10.1111/j.1365-246x.1990.tb00544.x
Weber, M., & Körnig, M. (1992). A search for anomalies in the lowermost mantle using seismic bulletins. Physics of the Earth and Planetary Interiors, 73(1–2), 1–28. https://doi.org/10.1016/0031-9201(92)90104-4
Wessel, P., & Smith, W. H. F. (1995). New version of the generic mapping tools. Eos, Transactions American Geophysical Union, 76(33), 329–329. https://doi.org/10.1029/95eo00198
Wolf, J., Long, M. D., Li, M., & Garnero, E. (2023). Global Compilation of Deep Mantle Anisotropy Observations and Possible Correlation With Low Velocity Provinces. Geochemistry, Geophysics, Geosystems, 24(10). https://doi.org/10.1029/2023gc011070
Wookey, J., Stackhouse, S., Kendall, J.-M., Brodholt, J., & Price, G. D. (2005). Efficacy of the post-perovskite phase as an explanation for lowermost-mantle seismic properties. Nature, 438(7070), 1004–1007. https://doi.org/10.1038/nature04345
Wright, C., & Kuo, B.-Y. (2007). The P-wavespeed structure in the lowermost 700km of the mantle below the central part of the Indian Ocean. Physics of the Earth and Planetary Interiors, 161(3–4), 243–266. https://doi.org/10.1016/j.pepi.2007.02.006
Wright, C., Muirhead, K. J., & Dixon, A. E. (1985). The P wave velocity structure near the base of the mantle. Journal of Geophysical Research: Solid Earth, 90(B1), 623–634. https://doi.org/10.1029/jb090ib01p00623
Wysession, M. E., Lay, T., Revenaugh, J., Williams, Q., Garnero, E. J., Jeanloz, R., & Kellogg, L. H. (1998). The D″ discontinuity and its implications. In The Core‐Mantle Boundary Region (pp. 273–297). American Geophysical Union. https://doi.org/10.1029/gd028p0273
Yamada, A., & Nakanishi, I. (1996). Detection of P‐wave reflector in D″ beneath the south‐western Pacific using double‐array stacking. Geophysical Research Letters, 23(13), 1553–1556. https://doi.org/10.1029/96gl01564
Yamada, A., & Nakanishi, I. (1998). Short‐wavelength lateral variation of a D′′ P‐wave reflector beneath the southwestern Pacific. Geophysical Research Letters, 25(24), 4545–4548. https://doi.org/10.1029/1998gl900188
Young, C. J., & Lay, T. (1987). Evidence for a shear velocity discontinuity in the lower mantle beneath India and the Indian Ocean. Physics of the Earth and Planetary Interiors, 49(1–2), 37–53. https://doi.org/10.1016/0031-9201(87)90131-2
Yu, S., & Garnero, E. J. (2018). Ultralow Velocity Zone Locations: A Global Assessment. Geochemistry, Geophysics, Geosystems, 19(2), 396–414. https://doi.org/10.1002/2017gc007281
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Norges Forskningsråd
Grant numbers 223272 (CEED);332523 (PHAB);326238 (POLARIS) -
Deutsche Forschungsgemeinschaft
Grant numbers TH1530/25-1
