Evolution of the Southwest Australian Rifted Continental Margin During Breakup of East Gondwana: Results From International Ocean Discovery Program Expedition 369
Evolution of the Southwest Australian Rifted Continental Margin During Breakup of East Gondwana: Results From International Ocean Discovery Program Expedition 369
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DOI：
10.1029/2020gc009144
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发表时间：
2020-11
期刊：
影响因子：
3.7
通讯作者：
D. Harry;M. Tejada;E. Lee;E. Wolfgring;C. Wainman;H. Brumsack;B. Schnetger;Jun-Ichi Kimura;L. Riquier;I. Borissova;R. Hobbs;T. Jiang;Y.X. Li;A. Maritati;Mathieu Martinez;C. Richter;G. Tagliaro;L. T. White
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作者：
D. Harry;M. Tejada;E. Lee;E. Wolfgring;C. Wainman;H. Brumsack;B. Schnetger;Jun-Ichi Kimura;L. Riquier;I. Borissova;R. Hobbs;T. Jiang;Y.X. Li;A. Maritati;Mathieu Martinez;C. Richter;G. Tagliaro;L. T. White
国际海洋发现计划第 369 号探险队在澳大利亚西南部大陆边缘、深水门特尔盆地 (MB) 和邻近的博物学家高原 (NP) 钻探了四个地点。这些钻探地点位于大陆地壳上，在磁时年 M11r 和 M11n (133–132 Ma) 之间的珀斯深渊平原 (PAP) 海底扩张开始后，大陆地壳持续裂谷，并在磁时年 M5n 和 M3n (126–124 Ma) 之间的 NP 西部开始扩张时结束。钻探回收了北卡罗来纳州破碎不整合面上的第一批玄武岩流原位样本，确定了磁地层限制的>131-133 Ma的喷发年龄，并确认了破碎不整合面的最小晚凡兰吉阶年龄（与PAP海底扩张的开始同时期）。岩石成因模型表明，玄武岩是在 1.5 GPa 压力和 1380°C–1410°C 潜在温度下熔化 25% 生成的，这与凯尔盖朗地幔柱破裂时的接近程度一致。底栖有孔虫化石表明，在裂谷的最后 6 密尔期间以及印度和澳大利亚分裂后的 3-5 密尔期间，NP 仍处于上半海或更浅的深度。有限的沉降归因于附近凯尔盖朗羽流和 PAP 扩张脊的热量。到阿尔布阶时期，边缘沉降到中深海深度，到古近纪晚期，边缘沉降到下深海（NP）或更大（MB）深度。快速沉积期伴随着PAP扩张脊向西跳跃（108Ma）、南缘裂谷（100-84Ma）以及澳大利亚和南极洲之间的南部海道的开放（60-47Ma）。
International Ocean Discovery Program Expedition 369 drilled four sites on the southwestern Australian continental margin, in the deep water Mentelle Basin (MB) and on the neighboring Naturaliste Plateau (NP). The drillsites are located on continental crust that continued rifting after seafloor spreading began further north on the Perth Abyssal Plain (PAP) between magnetochrons M11r and M11n (133–132 Ma), ending when spreading began west of the NP between chrons M5n and M3n (126–124 Ma). Drilling recovered the first in situ samples of basalt flows overlying the breakup unconformity on the NP, establishing a magnetostratigraphically constrained eruption age of >131–133 Ma, and confirming a minimal late Valanginian age for the breakup unconformity (coeval with the onset of PAP seafloor spreading). Petrogenetic modeling indicates the basalts were generated by 25% melting at 1.5 GPa and a potential temperature of 1380°C–1410°C, consistent with proximity of the Kerguelen plume during breakup. Benthic foraminiferal fossils indicate that the NP remained at upper bathyal or shallower depths during the last 6 Myr of rifting and for 3–5 Myr after breakup between India and Australia. The limited subsidence is attributed to heat from the nearby Kerguelen plume and PAP spreading ridge. The margin subsided to middle bathyal depths by Albian time and to lower bathyal (NP) or greater (MB) depths by late Paleogene time. Periods of rapid sedimentation accompanied a westward jump of the PAP spreading ridge (108 Ma), rifting on the southern margin (100–84 Ma), and opening of the southern seaway between Australia and Antarctica (60–47 Ma).