Cocos (Keeling) Islands, and Christmas Island. While recent geochronological investigations have shed light on the diverse eruption ages of the volcanics of this region, some islands/seamounts have demonstrated protracted volcanic histories, and it is not clear how the volcanic loading, tectonic subsidence, and subsequent emergence history of the islands relates to these discrete volcanic episodes. This study utilises a number of geophysical techniques to determine the crustal structure, loading and subsidence history, and last sub-aerial exposure age for the CHRISP. The study shows that flexural and subsidence modelling are reliable techniques in constraining the age of the seamounts when geochronological techniques are not possible. Utilising regional gravity signatures, we model the crustal structure underneath the Cocos (Keeling) Island, and constrain the thickness of the limestone cover between 900 and 2,100?m. Using age-depth subsidence curves for oceanic lithosphere the time since these seamounts were exposed above sea-level was determined, and a trend in exposure ages that youngs towards the west is observed. Two episodes of volcanism have been recorded at Christmas Island and they are of different origin. The younger phase in the Pliocene is a manifestation of flexure induced cracks produced in the lithosphere as it rides the subduction fore-bulge, whereas a low velocity seismic zone rising from the lower mantle, and tectonic reorganization, may be associated with the older Eocene volcanic phase, as well as much of the rest of the province. Our modelling also supports the existence of an older, undated volcanic core to Christmas Island, based on the loading ages from flexural modelling." />
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Constraining the age and origin of the seamount province in the Northeast Indian Ocean using geophysical techniques
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  • 作者:Rajat Taneja (1)
    Craig O’Neill (1)
  • 关键词:Indian Ocean ; Seamounts ; Plate flexure ; Seismic tomography ; Petit spot volcanism ; Capricorn Plate ; Age ; depth subsidence ; Plumes
  • 刊名:Marine Geophysical Researches
  • 出版年:2014
  • 出版时间:December 2014
  • 年:2014
  • 卷:35
  • 期:4
  • 页码:395-417
  • 全文大小:14,344 KB
  • 参考文献:1. Abercrombie RE, Antolik M, Ekstr?m G (2003) The June 2000 Mw 7.9 earthquakes south of Sumatra: deformation in the India–Australia Plate. J Geophys Res 108(B1):2018. doi:10.1029/2001jb000674 CrossRef
    2. Aitchison JC, Ali JR, Davis AM (2007) When and where did India and Asia collide? J Geophys Res 112(B5):B05423. doi:10.1029/2006jb004706
    3. Andrews CW (ed) (1900) A monograph of Christmas Island (Indian Ocean): physical features and geology. British Museum (Natural History), London
    4. Baxter JL, Weeks GC (1984) Phosphatised volcanic ore from the Christmas Island, Indian Ocean. Western Australia Institute of Technology
    5. Bodine J, Steckler M, Watts A (1981) Observations of flexure and the rheology of the oceanic lithosphere. J Geophys Res 86(B5):3695-707. doi:10.1029/JB086iB05p03695 CrossRef
    6. Calmant S, Cazenave A (1986) The effective elastic lithosphere under the Cook-Austral and Society Islands. Earth Planet Sci Let 77(2):187-02. doi:10.1016/0012-821X(86)90160-3 CrossRef
    7. Chapple WM, Forsyth DW (1979) Earthquakes and bending of plates at trenches. J Geophys Res 84(B12):6729-749. doi:10.1029/JB084iB12p06729 CrossRef
    8. Cloetingh S, Wortel R (1985) Regional stress field of the Indian Plate. Geophys Res Lett 12(2):77-0. doi:10.1029/GL012i002p00077 CrossRef
    9. Courtillot V, Davaille A, Besse J, Stock J (2003) Three distinct types of hotspots in the Earth’s mantle. Earth Planet Sci Lett 205(3-):295-08. doi:10.1016/S0012-821X(02)01048-8 CrossRef
    10. Darwin C (1842) The structure and distribution of coral reefs. Being the first part of the geology of the voyage of the beagle, under the command of Capt. Fitzroy, R.N. during the years 1832 to 1836. Smith, Elder and Co., London
    11. Davies HL, Ss Sun, Frey FA, Gautier I, McCulloch MT, Price RC, Bassias Y, Klootwijk CT, Leclaire L (1989) Basalt basement from the Kerguelen Plateau and the trail of a Dupal plume. Contrib Mineral Petrol 103(4):457-69. doi:10.1007/bf01041753 CrossRef
    12. Davy B, Wood R (1994) Gravity and magnetic modelling of the Hikurangi Plateau. Mar Geol 118(1-):139-51. doi:10.1016/0025-3227(94)90117-1 CrossRef
    13. DePaolo DJ, Manga M (2003) Deep origin of hotspots-the mantle plume model. Science 300(5621):920 CrossRef
    14. Detrick RS, Crough ST (1978) Island subsidence, hot spots, and lithospheric thinning. J Geophys Res 83:1236-244 CrossRef
    15. Dominguez S, Lallemand S, Malavieille J, von Huene R (1998) Upper plate deformation associated with seamount subduction. Tectonophysics 293(3):207-24. doi:10.1016/S0040-1951(98)00086-9 CrossRef
    16. Duncan RA (1978) Geochronology of basalts from the Ninetyeast Ridge and continental dispersion in the eastern Indian Ocean. J Volcanol Geotherm Res 4(3-):283-05. doi:10.1016/0377-0273(78)90018-5 CrossRef
    17. Duncan RA (1991) 26. Age distribution of volcanism along aseismic ridges in the eastern Indian Ocean. In: Weissel J, Peirce J, Taylor E, Alt J (eds) Proceedings of the Ocean Drilling Program, Scientific Results, vol 121. Ocean Drilling Program, College Station, pp 507-17
  • 作者单位:Rajat Taneja (1)
    Craig O’Neill (1)

    1. Department of Earth and Planetary Sciences, Australian Research Council Centre of Excellence for Core to Crust Fluid Systems/GEMOC, Macquarie University, Sydney, Australia
  • ISSN:1573-0581
文摘
The breakup of western margin of Australia from Greater India started around 155?Ma and progressed southwards. After the separation, the interceding intraplate region experienced large volumes of submarine volcanism, extending over 100?Myrs. The Christmas Island Seamount Province (CHRISP, as it has been dubbed) lies south of the Java-Sunda Trench, and contains numerous submerged volcanic seamounts, and two sub-aerially exposed island groups-a href='/search?dc.title=Cocos+%28Keeling%29+Islands&facet-content-type=ReferenceWorkEntry&sortOrder=relevance' class='reference-link webtrekk-track' gaCategory="Internal link" gaLabel="Cocos (Keeling) Islands" gaAction="reference keyword">Cocos (Keeling) Islands, and Christmas Island. While recent geochronological investigations have shed light on the diverse eruption ages of the volcanics of this region, some islands/seamounts have demonstrated protracted volcanic histories, and it is not clear how the volcanic loading, tectonic subsidence, and subsequent emergence history of the islands relates to these discrete volcanic episodes. This study utilises a number of geophysical techniques to determine the crustal structure, loading and subsidence history, and last sub-aerial exposure age for the CHRISP. The study shows that flexural and subsidence modelling are reliable techniques in constraining the age of the seamounts when geochronological techniques are not possible. Utilising regional gravity signatures, we model the crustal structure underneath the Cocos (Keeling) Island, and constrain the thickness of the limestone cover between 900 and 2,100?m. Using age-depth subsidence curves for oceanic lithosphere the time since these seamounts were exposed above sea-level was determined, and a trend in exposure ages that youngs towards the west is observed. Two episodes of volcanism have been recorded at Christmas Island and they are of different origin. The younger phase in the Pliocene is a manifestation of flexure induced cracks produced in the lithosphere as it rides the subduction fore-bulge, whereas a low velocity seismic zone rising from the lower mantle, and tectonic reorganization, may be associated with the older Eocene volcanic phase, as well as much of the rest of the province. Our modelling also supports the existence of an older, undated volcanic core to Christmas Island, based on the loading ages from flexural modelling.

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