有效弹性厚度(Te)表示岩石圈抵抗变形的能力,其大小主要取决于岩石圈内部的温度结构和地壳物质组成。作为全球最长的海岭之一,东经九十度海岭(NER)来源与形成过程一直是国内外科学家研究的热点,然而受到该地区复杂构造活动的影响,研究者对海岭的形成过程仍缺乏清晰认识。本文从Te的角度出发,通过空间褶积方法计算了沿着NER不同位置处Te的空间分布特征。计算结果表明,整个海岭的Te主要在0~35 km之间变化,表现为北(8°N~1°N)高(平均值为20 km)、中(1°N~15°S)低(平均值在5 km以下)、南(15°S~30°S)高(平均值为30 km),变化趋势与凯尔盖朗热点的3期岩浆活动相对应。Te的变化反映了NER形成过程中东南印度洋脊与热点的相对位置的调整,说明NER是凯尔盖朗热点、印度洋板块扩张与东南印度洋洋中脊迁移三者共同作用的结果。最后,结合Te的结果与ROYER板块重构的结果,本文提出了NER形成过程的模式。
Abstract
The effective elastic thickness(Te) which depends on the deep lithospheric temperature structure and crustal compositions, represents the lithospheric ability to resist deformation. The Ninetyeast Ridge(NER), one of the longest seamount in the world, has been studied by many researchers over its original and process. However, the complicated tectonic activities cause that it is too difficult to uncover the evolution of the NER. Here we investigated the NER in terms of Te with convolution method and obtained its spatial variations of Te. The results show that values vary from 0 to 35 km. Te is characterized as high value (averaging 20 km) in the north section (8°N~1°N), low value (averaging less than 5 km) in the middle part (1°N~15°S) and high value (averaging 30 km) in the south section (15°S~30°S), which are associated with three stages of volcanic activities of Kerguelen hotspot. In addition, the variations of values reflect the adjustment of relative position between Southeast Indian Ridge and hot spot during the evolution of NER and further prove that the NER is influenced and controlled by the Kerguelen hotspot, Indian plate's drift and Southeast Indian Ridge's jump. Finally, by combining with the evidence of ROYER's plate reconstruction, a model was proposed to show the evolution of Ninetyeast Ridge.
关键词
褶积算法 /
有效弹性厚度 /
东经九十度海岭 /
构造演化
Key words
convolution method /
effective elastic thickness /
Ninetyeast Ridge /
tectonic evolution
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参考文献
[1] KOPPERS A, P WATTSA B. Intraplate seamounts as a window into deep Earth processes[J]. Oceanography,2010,23(1):43-44.
[2] PEIRCE J W. The origin of Ninetyeast Ridge and the northward motion of Indian, based on DSDP paleomagnetics[D].Boston: MIT and Woods Hole Oceanographic Institution,1968:40-46.
[3] ROYER J Y, PIERCE J W, WEISSEL J K. Tectonics constraints on the hot-spot formation of Ninetyeast ridge[R]// Processing of the Ocean Drilling Program, Scientific Results,1991,121:763-775.
[4] MUNSCHY M, DYMENT J, BOULANGER M, et al. Breakup and seafloor spreading between the Kerguelen Plateau-Labuan Basin and the Broken Ridge-Diamantia Zone[R]// Processing of the Ocean Drilling Program, Scientific Results,1992,120:931-944.
[5] COFFIN M F, PRINGLE M S, DUNGAN R A, et al. Kerguelen hotspot magma output since 130 Ma[J]. Petrology,2002,43(7):1 121-1 139.
[6] LIU C S, CURRAY J R, MCDONALD J M. New constrains on the tectonic evolution of the eastern Indian Ocean[J]. Earth Planet Sci Lett,1983,65:331-342.
[7] GREVEMEYER I, FLUCH E R, REICHERT C, et al. Crustal architecture and deep structure of the Ninetyeast Ridge hotspot trail from active-source ocean bottom seismology[J].Geophys J Int,2001,144(2):414-431.
[8] AMANTE C, EAKINS B W. Etopo1 1 Arc-minute global relief model: Procedures, data sources and analysis[R]. NOAA Technical Memorandum,2009:1-19.
[9] WATTS A B, COCHRAN J R. Gravity anomalies and flexure of the lithosphere along the Hawaiian-Emperor seamount chain[J]. Geophys J R,1973,38:119-141.
[10] CHAND S, RADHAKRISHNA M,SUBRAHMANYAM C. India-East Antarctica conjugate margins: Rift-shear tectonic setting inferred from gravity and bathymetry data[J]. Earth Planet Sci Lett,2001,185:225-236.
[11] BRAITENBERG C,EBBLING J,COTEZE H J.Inverse modeling of elastic thickness by convolution method——the eastern Alps as a case example[J]. Earth Planet Sci bLett,2002,202:387-404.
[12] HERTZ H. On the equilibrium of floating elastic plates[J]. Ann Phys Chem,1884,22:449-455.
[13] WIENECKE S. A new analytical solution for the calculation of flexural rigidity: Significance and applications[D]. Berlin :Free University of Berlin,2005:19-69.
[14] BRAITENBERG C, WANG Y, FANG J, et al. Spatial variations of flexure parameters over the Tibet-Quinghai plateau[J]. Earth planet Sci Lett,2003,205:211-224.
[15] STEIN C A, STEIN S. A model for the global variation in oceanic depth and heat flow with lithosphere age[J]. Nature,1992,359(6391):123-129.
[16] PARKER R L. The Rapid calculation of potential anomalies[J]. J Geophys Res,1972,31:447-455.
[17] ARK E V, LIN J. Time variation in igneous volume flux of the Hawaii-Emperor hot spot seamount chain[J]. J Geophys Res,2004,109(B11401):1-18.
[18] VIDAL V, BONNEVILLE A. Variations of the Hawaiian hot spot activity revealed by variations in the magma production rate[J]. J Geophys Res,2004,109(B03104):1-13.
[19] ADAM C, VIDAL V, ESCARTIN J. 80-Myr history of buoyancy and volcanic fluxes along the trails of the Walvis and St. Helena hotspots (South Atlantic)[J]. Earth Planet Sci Lett,2007,261(3):432-442.
[20] WATTS A B. An analysis of isostasy in the world’s oceans 1.Hawaiian-Emperor seamount chain[J]. J Geophys Res,1978,83(B12):5 989-6 004.
[21] SCLATER J G, FISHER R L. The evolution of the east central Indian Ocean with emphasis on the tectonic setting of the Ninetyeast Ridge[J]. Geological Society of America Bulletin,1974,85(5):683-702.
[22] SETON M, WHITTAKER J M, WESSEL P, et al. Community infrastructure and repository for marine magnetic identifications[J]. Geochem Geophys Geosyst,2014,15(4):1 629-1 641.
[23] WATTS A B. Isostasy and flexure of the lithosphere[M]. Cambridge UK: Cambridge University Press,2001:230-248.
[24] ROYER J Y, SANDWELL D T. Evolution of the eastern Indian Ocean since the late Cretaceous: constrains from geosat altimetry[J]. J Geophys Res,1989,94(B10):13 775-13 782.
基金
南北极环境综合考察与评估专项项目资助(CHINARE2015-01-03,CHINARE2015-04-01,CHINARE2015-03-03,CHINARE2015-03-04)
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