Hostname: page-component-cd9895bd7-gxg78 Total loading time: 0 Render date: 2024-12-25T08:20:57.572Z Has data issue: false hasContentIssue false
  • English
  • Français

Cambrian to early Silurian ophiolite and accretionary processes in the Beishan collage, NW China: implications for the architecture of the Southern Altaids

Published online by Cambridge University Press:  20 October 2011

S. J. AO ,
W. J. XIAO ,
C. M. HAN ,
X. H. LI ,
J. F. QU ,
J. E. ZHANG ,
Q. Q. GUO  and
Z. H. TIAN
S. J. AO*
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
W. J. XIAO
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
C. M. HAN
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
X. H. LI
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
J. F. QU
Affiliation:
Institute of Geology, Chinese Academy of Geological Sciences, Beijing 100037, China
J. E. ZHANG
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
Q. Q. GUO
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
Z. H. TIAN
Affiliation:
State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China
*
†Author for correspondence: [email protected]
Get access Rights & Permissions [Opens in a new window]

Abstract

The mechanism of continental growth of the Altaids is currently under debate between models invoking continuous subduction-accretion or punctuated accretion by closure of multiple ocean basins. We use the Yueyashan–Xichangjing ophiolite belt of the Beishan collage (southern Altaids) to constrain the earliest oceanic crust in the southern Palaeo-Asian Ocean. Five lithotectonic units were identified from S to N: the Huaniushan block, a sedimentary passive margin, the structurally incoherent Yueyashan–Xichangjing ophiolite complex, a coherent sedimentary package and the Mazongshan island arc with granitic rocks. We present a structural analysis of the accretionary complex, which is composed of the incoherent ophiolitic melange and coherent sedimentary rocks, to work out the tectonic polarity. A new weighted mean 206Pb–238U age of 533 ± 1.7 Ma from a plagiogranite in the Yueyashan–Xichangjing ophiolite indicates that the ocean floor formed in early Cambrian time. Furthermore, we present new geochemical data to constrain the tectonic setting of the Yueyashan–Xichangjing ophiolite. The Yueyashan–Xichangjing ophiolite was emplaced as a result of northward subduction of an oceanic plate beneath the Mazongshan island arc to the north in late Ordovician to early Silurian time. Together with data from the literature, our work demonstrates that multiple overlapping periods of accretion existed in the Palaeozoic in the northern and southern Altaids. Therefore, a model of multiple accretion by closure of several ocean basins is most viable.

Keywords

BeishanYueyashan–Xichangjingophioliteaccretionary complexAltaids
Type
Original Articles
Information
Geological Magazine , Volume 149 , Issue 4 , July 2012 , pp. 606 - 625
Copyright
Copyright © Cambridge University Press 2011

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

References

Abrajevitch, A., Van der Voo, R., Levashova, N. M. & Bazhenov, M. L. 2007. Paleomagnetic constraints on the paleogeography and oroclinal bending of the Devonian volcanic arc in Kazakhstan. Tectonophysics 441, 67–84.CrossRefGoogle Scholar
Anonymous. 1977. Geological Map of the Wudaoming Region, China, 1:200,000. The Geomechanics and Regional Geological Team of the Gansu Bureau of Geology (in Chinese).Google Scholar
Anonymous. 1979. Geological Map of the Lujing Region, China, 1:200,000. The Geomechanics and Regional Geological Team of the Gansu Bureau of Geology (in Chinese).Google Scholar
Ao, S. J., Xiao, W. J., Han, C. M., Mao, Q. G. & Zhang, J. E. 2010. Geochronology and geochemistry of Early Permian mafic-ultramafic complexes in the Beishan area, Xinjiang, NW China: implications for late Paleozoic tectonic evolution of the southern Altaids. Gondwana Research 18, 466–78.CrossRefGoogle Scholar
Batkhishig, B., Noriyoshi, T. & Greg, B. 2010. Magmatism of the Shuteen Complex and Carboniferous subduction of the Gurvansaikhan terrane, South Mongolia. Journal of Asian Earth Sciences 37, 399–411.Google Scholar
Bazhenov, M. L., Collins, A. Q., Degtyarev, K. E., Levashova, N. M., Mikolaichuk, A. V., Pavlov, V. E. & Van der Voo, R. 2003. Paleozoic northward drift of the North Tien Shan (Central Asia) as revealed by Ordovician and Carboniferous paleomagnetism. Tectonophysics 366, 113–41.Google Scholar
Brenan, J. M., Shaw, H. F., Phinney, D. L. & Ryerson, F. J. 1994. Rutile-aqueous fluid partitioning of Nb, Ta, Hf, Zr, U and Th: implications for high field strength element depletions in island-arc basalts. Earth and Planetary Science Letters 128, 327–39.CrossRefGoogle Scholar
Brenan, J. M., Shaw, H. F., Ryerson, F. J. & Phinney, D. L. 1995. Mineral-aqueous fluid partitioning of trace-elements at 900-degrees-C and 2.0 GPa – constraints on the trace-element chemistry of mantle and deep-crustal fluids. Geochimica et Cosmochimica Acta 59, 3331–50.CrossRefGoogle Scholar
Buchan, C., Cunningham, D., Windley, B. F. & Tomurhuu, D. 2001. Structural and lithological characteristics of the Bayankhongor Ophiolite Zone, Central Mongolia. Journal of the Geological Society, London 158, 445–60.CrossRefGoogle Scholar
Carroll, A. R., Graham, S. A., Hendrix, M. S., Ying, D. & Zhou, D. 1995. Late Paleozoic tectonic amalgamation of northwestern China: sedimentary record of the northern Tarim, northwestern Turpan, and southern Junggar Basins. Geological Society of America Bulletin 107, 571–94.Google Scholar
Carroll, A. R., Yunhai, L., Graham, S. A., Xuchang, X., Hendrix, M. S., Jinchi, C. & McKnight, C. L. 1990. Junggar basin, northwest China: trapped Late Paleozoic ocean. Tectonophysics 181, 1–14.CrossRefGoogle Scholar
Cawood, P. A., Kröner, A., Collins, W. J., Kusky, T. M., Mooney, W. D. & Windley, B. F. 2009. Accretionary orogens through Earth history. In Earth Accretionary Systems in Space and Time (eds P. A. Cawood & A. Kröner), pp. 1–36. Geological Society of London, Special Publication no. 318.Google Scholar
Coleman, R.G. 1989. Continental growth of Northwest China. Tectonics 8, 621–35.CrossRefGoogle Scholar
Collins, A. Q., Degtyarev, K. E., Levashova, N. M., Bazhenov, M. L. & Van der Voo, R. 2003. Early Paleozoic paleomagnetism of east Kazakhstan: implications for paleolatitudinal drift of tectonic elements within the Ural-Mongol belt. Tectonophysics 377, 229–47.CrossRefGoogle Scholar
Cunningham, D. 2005. Active intracontinental transpressional mountain building in the Mongolian Altai: defining a new class of orogen. Earth and Planetary Science Letters 240, 436–44.CrossRefGoogle Scholar
Cunningham, D. 2007. Structural and topographic characteristics of restraining bend mountain ranges of the Altai, Gobi Altai and easternmost Tien Shan. In Tectonics of Strike-Slip Restraining and Releasing Bends (eds W. D. Cunningham & P. Mann), pp. 219–37. Geological Society of London, Special Publication no. 290.Google Scholar
Dhuime, B., Bosch, D., Bodinier, J. L., Garrido, C. J., Bruguier, O., Hussain, S. S. & Dawood, H. 2007. Multistage evolution of the Jijal ultramafic-mafic complex (Kohistan, N Pakistan): implications for building the roots of island arcs. Earth and Planetary Science Letters 261, 179–200.CrossRefGoogle Scholar
Dilek, Y. & Furnes, H. 2011. Ophiolite genesis and global tectonics: geochemical and tectonic fingerprinting of ancient oceanic lithosphere. Geological Society of America Bulletin 123, 387–411.CrossRefGoogle Scholar
Dobretsov, N. L. 2003. Evolution of structures of the Urals, Kazakhstan, Tienshan and Altai-Sayan region within the Ural-Mongolian fold belt. Russian Geology and Geophysics 44, 3–26.Google Scholar
Dobretsov, N. L. & Buslov, M. M. 2007. Late Cambrian-Ordovician tectonics and geodynamics of Central Asia. Russian Geology and Geophysics 48, 71–82.Google Scholar
Dobretsov, N. L., Buslov, M. M. & Vernikovsky, V. A. 2003. Neoproterozoic to Early Ordovician evolution of the Paleo-Asian Ocean: implications to the break-up of Rodinia. Gondwana Research 6, 143–59.Google Scholar
Ellam, R. M. & Hawkesworth, C. J. 1988. Elemental and isotopic variations in subduction related basalts – evidence for a three component model. Contributions to Mineralogy and Petrology 98, 72–80.CrossRefGoogle Scholar
Floyd, P. A., Yaliniz, M. K. & Goncuoglu, M. C. 1998. Geochemistry and petrogenesis of intrusive and extrusive ophiolitic plagiogranites, Central Anatolian Crystalline Complex, Turkey. Lithos 42, 225–41.Google Scholar
Gong, Q. S., Liu, M. Q., Liang, M. H. & Li, H. L. 2003. The tectonic facies and tectonic evolution of Beishan orogenic belt, Gansu. Northwestern Geology 1, 11–17 (in Chinese with English abstract).Google Scholar
He, S. P., Ren, B. C., Yao, W. G. & Fu, L. P. 2002. The division of tectonic units of Beishan area, Gansu-Inner Mongolia. Northwestern Geology 4, 30–40 (in Chinese with English abstract).Google Scholar
He, S. P., Zhou, H. W., Ren, B. C., Yao, W. G. & Fu, L. P. 2005. Crustal evolution of Palaeozoic in Beishan area, Gansu and Inner Mongolia, China. Northwestern Geology 3, 6–15 (in Chinese with English abstract).Google Scholar
Hsu, K. J., Yao, Y. Y., Li, J. L. & Wang, Q. C. 1992. Geology of the Beishan Mountains and the tectonic evolution of Northwest China. Eclogae Geologicae Helvetiae 85, 213–25.Google Scholar
Huang, Z. B. & Jin, X. 2006. Geological characteristics and its setting for volcanic rocks of Baishan formation in Hongshishan area of Gansu Province. Gansu Geology 15, 19–24 (in Chinese).Google Scholar
Jahn, B. M., Windley, B., Natal'in, B. & Dobretsov, N. 2004. Phanerozoic continental growth in central Asia Preface. Journal of Asian Earth Sciences 23, 599–603.CrossRefGoogle Scholar
Jahn, B. M., Wu, F. Y. & Chen, B. 2000 a. Granitoids of the Central Asian Orogenic Belt and continental growth in the Phanerozoic. Transactions of the Royal Society of Edinburgh: Earth Sciences 91, 181–93.CrossRefGoogle Scholar
Jahn, B. M., Wu, F. Y. & Chen, B. 2000 b. Massive granitoid generation in Central Asia: Nd isotope evidence and implication for continental growth in the Phanerozoic. Episodes 23, 82–92.CrossRefGoogle Scholar
Khain, E. V., Bibikova, E. V., Kröner, A., Zhuravlev, D. Z., Sklyarov, E. V., Fedotova, A. A. & Kravchenko-Berezhnoy, I. R. 2002. The most ancient ophiolite of the Central Asian fold belt: U-Pb and Pb-Pb zircon ages for the Dunzhugur Complex, Eastern Sayan, Siberia, and geodynamic implications. Earth and Planetary Science Letters 199, 311–25.Google Scholar
Khain, E. V., Bibikova, E. V., Salnikova, E. B., Kröner, A., Gibsher, A. S., Didenko, A. N., Degtyarev, K. E. & Fedotova, A. A. 2003. The Palaeo-Asian ocean in the Neoproterozoic and early Palaeozoic: new geochronologic data and palaeotectonic reconstructions. Precambrian Research 122, 329–58.CrossRefGoogle Scholar
Kwon, S. T., Tilton, G. R., Coleman, R. G. & Feng, Y. 1989. Isotopic studies bearing on the tectonics of the West Junggar region, Xinjiang, China. Tectonics 84, 719–27.Google Scholar
Le Maitre, R. W., Bateman, P., Dudek, A., Keller, J., Lameyre Le Bas, M. J., Sabine, P. A., Schmid, R., Sorensen, H., Streckeisen, A., Woolley, A. R. & Zanettin, B. 1989. A Classification of Igneous Rocks and a Glossary of Terms. Recommendations of the IGUS Subcommission on the Systematics of Igneous Rocks. Oxford: Blackwell.Google Scholar
Levashova, N. M., Mikolaichuk, A. V., McCausland, P. J. A., Bazhenov, M. L. & Van der Voo, R. 2007. Devonian paleomagnetism of the North Tien Shan: implications for the middle-Late Paleozoic paleogeography of Eurasia. Earth and Planetary Science Letters 257, 104–20.CrossRefGoogle Scholar
Li, X.-H. 1997. Geochemistry of the Longsheng Ophiolite from the southern margin of Yangtze Craton, SE China. Journal of Geochemistry 31, 323–37.Google Scholar
Li, Q.-L., Li, X.-H., Liu, Y., Tang, G. Q., Yang, J. H. & Zhu, W. G. 2010. Precise U-Pb and Pb-Pb dating of Phanerozoic baddeleyite by SIMS with oxygen flooding technique. Journal of Analytical Atomic Spectrometry 25, 1107–13.CrossRefGoogle Scholar
Li, X.-H., Liu, Y., Li, Q.-L., Guo, C.-H. & Chamberlain, K. R. 2009. Precise determination of Phanerozoic zircon Pb/Pb age by multicollector SIMS without external standardization. Geochemistry, Geophysics, Geosystems 10, Q04010, doi:10.1029/2009GC002400, 21 pp.Google Scholar
Li, X.-H., Li, Z. X., Wingate, M. T. D., Chung, S. L., Liu, Y., Lin, G. C. & Li, W. X. 2006. Geochemistry of the 755 Ma MundineWell dyke swarm, northwestern Australia: part of a Neoproterozoic mantle superplume beneath Rodinia? Precambrian Research 146, 1–15.Google Scholar
Liu, X. Y. & Wang, Q. 1995. Tectonics and evolution of the Beishan orogenic belt, West China. Geological Research 10, 151–65 (in Chinese with English abstract).Google Scholar
Ludwig, K. R. 2001. Users Manual for Isoplot/Ex rev. 2.49. Berkeley Geochronology Centre Special Publication no. 1a, 56 pp.Google Scholar
Mao, J. W., Pirajno, F., Zhang, Z. H., Chai, F. M., Wu, H., Chen, S. P., Cheng, L. S., Yang, J. M. & Zhang, C. Q. 2008. A review of the Cu-Ni sulphide deposits in the Chinese Tianshan and Altay orogens (Xinjiang Autonomous Region, NW China): principal characteristics and ore-forming processes. Journal of Asian Earth Sciences 32, 184–203.CrossRefGoogle Scholar
Mao, Q. G., Xiao, W. J., Windley, B. F., Han, C. M., Qu, J. F., Ao, S. J., Zhang, J. E. & Guo, Q. Q. 2011. The Liuyuan complex in the Beishan, NW China: a Carboniferous–Permian fore-arc sliver in the southern Altaids. Geological Magazine. doi:10.1017/S0016756811000811.CrossRefGoogle Scholar
Moores, E. M. 1982. Origin and emplacement of ophiolites. Reviews of Geophysics and Space Physics 20, 735–60.CrossRefGoogle Scholar
Pearce, J. A. 1983. The role of sub-continental lithosphere in magma genesis at destructive plate margins. In Continental Basalts and Mantle Xenoliths (eds Hawkesworth, C. J. & Norry, M. J.), pp. 230–49. Cheshire: Shiva Publishing.Google Scholar
Pearce, J. A. 2008. Geochemical fingerprinting of oceanic basalts with applications to ophiolite classification and the search for Archean oceanic crust. Lithos 100, 14–48.Google Scholar
Pearce, J. A., Harris, J. & Tindle, A. 1984. Trace element discrimination diagrams for the tectonic interpretation of granitic rocks. Journal of Petrology 25, 956–83.CrossRefGoogle Scholar
Pearce, J. A. & Robinson, P. T. 2010. The Troodos ophiolitic complex probably formed in a subduction initiation, slab edge setting. Gondwana Research 18, 60–81.CrossRefGoogle Scholar
Pirajno, F., Mao, J. W., Zhang, Z. C., Zhang, Z. H. & Chai, F. M. 2008. The association of mafic-ultramafic intrusions and A-type magmatism in the Tian Shan and Altay orogens, NW China: implications for geodynamic evolution and potential for the discovery of new ore deposits. Journal of Asian Earth Sciences 32, 165–83.Google Scholar
Rippington, S., Cunningham, D. & England, R. 2008. Structure and petrology of the Altan Uul Ophiolite: new evidence for a Late Carboniferous suture in the Gobi Altai, southern Mongolia. Journal of the Geological Society, London 165, 711–23.Google Scholar
Rojas-Agramonte, Y., Kroner, A., Demoux, A., Xia, X., Wang, W., Donskaya, T., Liu, D. & Sun, M. 2011. Detrital and xenocrystic zircon ages from Neoproterozoic to Palaeozoic arc terranes of Mongolia: significance for the origin of crustal fragments in the Central Asian Orogenic Belt. Gondwana Research 19, 751–63.CrossRefGoogle Scholar
Şengör, A. M. C. & Natal'in, B. 1996. Paleotectonics of Asia: fragments of a synthesis. In The Tectonic Evolution of Asia (eds Yin, A. & Harrison, T. M.), pp. 486–641. Cambridge: Cambridge University Press.Google Scholar
Şengör, A. M. C., Natal'in, B.A. & Burtman, V. S. 1993. Evolution of the Altaid tectonic collage and Paleozoic crustal growth in Eurasia. Nature 364, 299–307.Google Scholar
Shervais, J. W. 1982. Ti-V plots and the petrogenesis of modern and ophiolitic lavas. Earth and Planetary Science Letters 59, 101–18.Google Scholar
Song, T. Z., Wang, J., Lin, H., Yang, X. F., Zhang, L. & An, S. W. 2008. The geological features of ophiolites of Xiaohuangshan in Beishan Area, Inner Mongolia. Northwestern Geology 3, 55–63 (in Chinese with English abstract).Google Scholar
Stacey, J. S. & Kramers, J. D. 1975. Approximation of terrestrial lead isotope evolution by a two-stage model. Earth and Planetary Science Letters 26, 207–21.Google Scholar
Stern, R. J. 2002. Subduction zones. Reviews of Geophysics 40, 1012.Google Scholar
Stern, R. J. & Bloomer, S. H. 1992. Subduction zone infancy: examples from the Eocene Izu-Bonin-Mariana and Jurassic California arcs. Geological Society of America Bulletin 104, 1621–36.Google Scholar
Sun, S.-S. & McDonough, W. F. 1989. Chemical and isotopic systematics of oceanic basalts: implications for mantle composition and process. In Magmatism in Ocean Basins (eds Saunders, A. D. & Norry, M. J.), pp. 313–45. Geological Society of London, Special Publication no. 42.Google Scholar
Wiedenbeck, M., Allé, P., Corfu, F., Griffin, W., Meier, M., Oberli, F., Quadt, A. V., Roddick, J. & Spiegel, W. 1995. Three natural zircon standards for U-Th-Pb, Lu-Hf, trace element and REE analyses. Geostandards and Geoanalytical Research 19, 1–23.Google Scholar
Windley, B. F., Alexeiev, D., Xiao, W. J., Kroner, A. & Badarch, G. 2007. Tectonic models for accretion of the Central Asian Orogenic Belt. Journal of the Geological Society, London 164, 31–47.CrossRefGoogle Scholar
Xiao, W. J., Han, C. M., Yuan, C., Sun, M., Lin, S. F., Chen, H. L., Li, Z. L., Li, J. L. & Sun, S. 2008. Middle Cambrian to Permian subduction-related accretionary orogenesis of Northern Xinjiang, NW China: implications for the tectonic evolution of central Asia. Journal of Asian Earth Sciences 32, 102–17.Google Scholar
Xiao, W. J., Huang, B. C., Han, C. M., Sun, S. & Li, J. L. 2010 a. A review of the western part of the Altaids: a key to understanding the architecture of accretionary orogens. Gondwana Research 18, 253–73.Google Scholar
Xiao, W. J., Mao, Q. G., Windley, B. F., Han, C. M., Qu, J. F., Zhang, J. E., Ao, S. J., Guo, Q. Q., Cleven, N. R., Lin, S. F., Shan, Y. H. & Li, J. L. 2010 b. Paleozoic multiple accretionary and collisional processes of the Beishan orogenic collage. American Journal of Science 310, 1553–94.CrossRefGoogle Scholar
Xiao, W., Windley, B. F., Badarch, G., Sun, S., Li, J., Qin, K. & Wang, Z. 2004 a. Palaeozoic accretionary and convergent tectonics of the southern Altaids: implications for the growth of Central Asia. Journal of the Geological Society, London 161, 339–42.Google Scholar
Xiao, W. J., Windley, B. F., Yuan, C., Sun, M., Han, C. M., Lin, S. F., Chen, H. L., Yan, Q. R., Liu, D. Y., Qin, K. Z., Li, J. L. & Sun, S. 2009. Paleozoic multiple subduction-accretion processes of the Southern Altaids. American Journal of Science 309, 221–70.CrossRefGoogle Scholar
Xiao, W. J., Zhang, L. C., Qin, K. Z., Sun, S. & Li, J. L. 2004 b. Paleozoic accretionary and collisional tectonics of the Eastern Tianshan (China): implications for the continental growth of Central Asia. American Journal of Science 304, 370–95.CrossRefGoogle Scholar
Zhang, Y. Y. & Guo, Z. J. 2008. Accurate constraint on formation and emplacement age of Hongliuhe ophiolite, boundary region between Xinjiang and Gansu Provinces and its tectonic implications. Acta Petrologica Sinica 24, 803–9 (in Chinese with English abstract).Google Scholar
Zhang, Z. H., Mao, J. W., Du, A. D., Pirajno, F., Wang, Z. L., Chai, F. M., Zhang, Z. C. & Yang, J. M. 2008. Re-Os dating of two Cu-Ni sulfide deposits in northern Xinjiang, NW China and its geological significance. Journal of Asian Earth Sciences 32, 204–17.Google Scholar
Zhou, G. Q., Zhao, J. X. & Li, X. H. 2000. Characteristics of the Yueyashan ophiolite from western Nei Mongol and its tectonic setting: geochemistry and Sm-Nd isotopic constraints. Geochimica 29, 108–19 (in Chinese with English abstract).Google Scholar
Zuo, G. C., Liu, Y. K. & Liu, C. Y. 2003. Framework and evolution of the tectonic structure in Beishan area across Gansu Province, Xinjiang Autonomous region and Inner Mongolia Autonomous Region. Acta Geologica Gansu 12, 1–15 (in Chinese with English abstract).Google Scholar
Zuo, G., Zhang, S. L., He, G. Q. & Zhang, Y. 1990 a. Early Paleozoic plate tectonics in Beishan area. Scientia Geologica Sinica 25, 305–14 (in Chinese with English abstract).Google Scholar
Zuo, G., Zhang, S., He, G. & Zhang, Y. 1991. Plate tectonic characteristics during the early paleozoic in Beishan near the Sino-Mongolian border region, China. Tectonophysics 188, 385–92.Google Scholar
Zuo, G. C., Zhang, S. L., Wang, X., Jin, S. Q., He, G. Q., Zhang, Y., Li, H. C. & Bai, W. C. 1990 b. Plate Tectonics and Metallogenic Regularities in Beishan Region. Peking University Publishing House, pp. 144–88 (in Chinese with English abstract).Google Scholar