Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean
The temporal relationship between tectonic and volcanic activity on passive continental margins immediately before and after the initiation of mid-ocean ridge spreading is poorly understood because of the scarcity of volcanic samples on which to perform isotope geochronology. We present the first ac...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal Article |
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GEOLOGICAL SOC AMER, INC
2015
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| Online Access: | http://hdl.handle.net/20.500.11937/27756 |
| _version_ | 1848752351194644480 |
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| author | Olierook, Hugo Merle, Renaud Jourdan, Fred Sircombe, K. Fraser, G. Timms, Nicholas Eric Nelson, G. Dadd, K. Kellerson, L. Borissova, I. |
| author_facet | Olierook, Hugo Merle, Renaud Jourdan, Fred Sircombe, K. Fraser, G. Timms, Nicholas Eric Nelson, G. Dadd, K. Kellerson, L. Borissova, I. |
| author_sort | Olierook, Hugo |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | The temporal relationship between tectonic and volcanic activity on passive continental margins immediately before and after the initiation of mid-ocean ridge spreading is poorly understood because of the scarcity of volcanic samples on which to perform isotope geochronology. We present the first accurate geochronological constraints from a suite of volcanic and volcaniclastic rocks dredged from the 70,000 km2 submerged Wallaby Plateau situated on the Western Australian passive margin. Plagioclase 40Ar/39Ar and zircon U-Pb sensitive high-resolution ion microprobe ages indicate that a portion of the plateau formed at ca. 124 Ma. These ages are at least 6 m.y. younger than the oldest oceanic crust in adjacent abyssal plains (minimum = 130 Ma). Geochemical data indicate that the Wallaby Plateau volcanic samples are enriched tholeiitic basalt, similar to continental flood basalts, including the spatially and temporally proximal Bunbury Basalt in southwestern Australia. Thus, the Wallaby Plateau volcanism could be regarded as a (small) flood basalt event on the order of 104-105 km3. We suggest that magma could not erupt prior to 124 Ma because of the lack of space adjacent to the plateau. Eruption was made possible at 124 Ma via the opening of the Indian Ocean during the breakup of Greater India and Australia along the Wallaby-Zenith Fracture Zone. The scale of volcanism and the temporal proximity to breakup challenges the prevailing theory that the Western Australian margin formed as a volcanic passive margin. Given that the volume of volcanism is too small for typical flood basalts associated with volcanic passive margins, we suggest that the two end members, magma-poor and volcanic passive margins, should rather be treated as a continuum. |
| first_indexed | 2025-11-14T08:07:14Z |
| format | Journal Article |
| id | curtin-20.500.11937-27756 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T08:07:14Z |
| publishDate | 2015 |
| publisher | GEOLOGICAL SOC AMER, INC |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-277562017-09-13T15:13:27Z Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean Olierook, Hugo Merle, Renaud Jourdan, Fred Sircombe, K. Fraser, G. Timms, Nicholas Eric Nelson, G. Dadd, K. Kellerson, L. Borissova, I. The temporal relationship between tectonic and volcanic activity on passive continental margins immediately before and after the initiation of mid-ocean ridge spreading is poorly understood because of the scarcity of volcanic samples on which to perform isotope geochronology. We present the first accurate geochronological constraints from a suite of volcanic and volcaniclastic rocks dredged from the 70,000 km2 submerged Wallaby Plateau situated on the Western Australian passive margin. Plagioclase 40Ar/39Ar and zircon U-Pb sensitive high-resolution ion microprobe ages indicate that a portion of the plateau formed at ca. 124 Ma. These ages are at least 6 m.y. younger than the oldest oceanic crust in adjacent abyssal plains (minimum = 130 Ma). Geochemical data indicate that the Wallaby Plateau volcanic samples are enriched tholeiitic basalt, similar to continental flood basalts, including the spatially and temporally proximal Bunbury Basalt in southwestern Australia. Thus, the Wallaby Plateau volcanism could be regarded as a (small) flood basalt event on the order of 104-105 km3. We suggest that magma could not erupt prior to 124 Ma because of the lack of space adjacent to the plateau. Eruption was made possible at 124 Ma via the opening of the Indian Ocean during the breakup of Greater India and Australia along the Wallaby-Zenith Fracture Zone. The scale of volcanism and the temporal proximity to breakup challenges the prevailing theory that the Western Australian margin formed as a volcanic passive margin. Given that the volume of volcanism is too small for typical flood basalts associated with volcanic passive margins, we suggest that the two end members, magma-poor and volcanic passive margins, should rather be treated as a continuum. 2015 Journal Article http://hdl.handle.net/20.500.11937/27756 10.1130/G37044.1 GEOLOGICAL SOC AMER, INC unknown |
| spellingShingle | Olierook, Hugo Merle, Renaud Jourdan, Fred Sircombe, K. Fraser, G. Timms, Nicholas Eric Nelson, G. Dadd, K. Kellerson, L. Borissova, I. Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title | Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title_full | Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title_fullStr | Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title_full_unstemmed | Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title_short | Age and geochemistry of magmatism on the oceanic Wallaby Plateau and implications for the opening of the Indian Ocean |
| title_sort | age and geochemistry of magmatism on the oceanic wallaby plateau and implications for the opening of the indian ocean |
| url | http://hdl.handle.net/20.500.11937/27756 |