The secular development of accretionary orogens: linking the Gondwana magmatic arc record of West Antarctica, Australia and South America
The secular development of accretionary orogens: linking the Gondwana magmatic arc record of West Antarctica, Australia and South America
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DOI：
10.1016/j.gr.2018.06.002
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发表时间：
2018-11
影响因子：
6.1
通讯作者：
D. Nelson;J. Cottle
中科院分区：
文献类型：
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作者：
D. Nelson;J. Cottle
结合南极玛丽伯德地东部和瑟斯顿岛的锆石年代学和深成岩的Hf同位素，提供了冈瓦纳古太平洋边缘显生宙弧岩浆活动的详细记录。南极边缘岩浆活动起源于罗斯造山运动时期（约540-485 Ma）一个同位素富集岩石圈地幔源的以收缩弧为主的环境。白垩纪罗斯造山运动结束后，碎屑锆石和火成岩锆石的锆石ε h值相对增加，反映了岩石圈尺度的伸展期，而在推断的南极边缘收缩期，锆石ε h值相对减少。将这一长期同位素进化趋势与古太平洋冈瓦纳边缘的类似数据进行比较，可以证明玛丽伯德地、澳大利亚和西兰迪亚之间有共同的历史，这与瑟斯顿岛、南极半岛和南美洲的共同记录形成了对比。这两个对比的历史突出了二叠世早期沿弧地球化学特征，并推断了地球动力学从南美洲、南极半岛和瑟斯顿岛的同位素富集的收缩弧系统到玛丽伯德兰、西兰迪亚和澳大利亚的同位素富集的伸展弧系统的转换。尽管在时间上存在差异，但古太平洋边缘的所有板块都经历了相似的长期同位素演化，在伸展崩塌期间同位素组成从富集到幼化的剧烈变化。
Combined zircon geochronology and Hf isotopes of plutonic rocks from eastern Marie Byrd Land and Thurston Island, Antarctica, provide a detailed record of Phanerzoic arc magmatism along the paleo-Pacific margin of Gondwana. Magmatism along the Antarctic margin initiated in a dominantly contractional arc setting with an isotopically enriched lithospheric mantle source during the Ross Orogeny (c. 540–485 Ma). After termination of the Ross Orogeny through the Cretaceous, detrital zircon and zircon from igneous rocks record relative increases in zircon εHfiinferred to represent episodes of lithospheric-scale extension and relative decreases during inferred contractional episodes along the Antarctic margin. Comparison of this secular isotopic evolutionary trend with similar data from along the paleo-Pacific margin of Gondwana demonstrates a shared history among Marie Byrd Land, Australia, and Zealandia that contrasts with the shared record of Thurston Island, Antarctic Peninsula, and South America. These two contrasting histories highlight an early Permian along arc geochemical and inferred geodynamic switch from an isotopically enriched contractional arc system in South America, Antarctic Peninsula, and Thurston Island to an isotopically depleted extensional arc system in Marie Byrd Land, Zealandia, and Australia. Despite differences in timing, all segments of the paleo-Pacific margin underwent a similar secular isotopic evolution with dramatic shifts from enriched to juvenile isotopic compositions during extensional collapse.