Mapping the 4D lithospheric architecture of Zealandia using zircon O and Hf isotopes in plutonic rocks
Mapping the 4D lithospheric architecture of Zealandia using zircon O and Hf isotopes in plutonic rocks
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使用深成岩中的锆石 O 和 Hf 同位素绘制西兰大陆 4D 岩石圈结构图
DOI：
10.1016/j.gr.2023.05.010
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发表时间：
2023
影响因子：
6.1
通讯作者：
Faure, K.
中科院分区：
文献类型：
--
作者：
Turnbull, R.E.;Schwartz, J.J.;Fiorentini, M.L.;Klepeis, K.A.;Jongens, R.;Miranda, E.;Evans, N.J.;Ludwig, T.;Waight, T.;Faure, K.
在这方面的贡献，我们研究了地壳结构的一个古生代的科迪勒拉边缘沿着的一段前冈瓦纳超大陆。西兰迪亚科迪勒拉，活跃在C。500 - 100 Ma，其特征是岩浆侵位在整个地壳柱，并表现出可变的全岩和锆石稳定和放射性同位素组成。利用新的和现有的原位锆石206 Pb-238 U，δ 18 O和Lu-Hf数据的266个深成岩石，我们创建多同位素等值线图，有效地描绘岩石圈结构。重要的是，我们证明了O和Hf同位素等值线图，结合206 Pb-238 U年龄控制和已发表的结构图，可以帮助确定影响岩浆活动的成分和位置的长期存在的深部地壳结构，以及促进和集中过去和最近的变形和断层。我们还提出了同位素二元混合模型的整个历史的中生代岩浆沿着Zealandia Cordillera。同位素混合模型是一致的混合各种表壳，原始下地壳深成，弧地幔源，每一个不同的年龄和成分。混合模型支持几个主要的净地壳生长和再循环事件。同位素定义的地壳区域（包括明显的轻δ 18 O值东部同位素域）在古生代-中生代的大小和成分上有所不同，这表明虽然岩石圈结构对岩浆作用和相关的成矿作用有一定的影响，但下板块过程及其相关的弧形构造几何形状在控制岩浆成分方面也有重要作用，重要的是岩浆“爆发”事件的数量和流量。最后，已发表的锆石O和Hf同位素数据沿着前冈瓦纳大陆东南边缘，使强大的相关性和比较，现在分离的大陆陆块。玛丽伯德地二叠纪岩石的δ 18 O值较轻，这一发现支持了以前西兰迪亚外侧中长石与阿蒙森省之间的相关性。
In this contribution, we examine the crustal architecture of a Phanerozoic Cordilleran margin along a segment of the former Gondwana supercontinent. The Zealandia Cordillera, active at c. 500 – 100 Ma, is characterized by magmas that were emplaced throughout the entire crustal column and exhibit variable whole-rock and zircon stable and radiogenic isotopic compositions. Using new and existing in-situ zircon206Pb-238U, δ18O and Lu-Hf data for 266 plutonic rocks, we create multi-isotope contour maps that are shown to effectively delineate lithospheric architecture. Importantly, we demonstrate that O and Hf isotope contour maps, in combination with206Pb-238U age control and published structural mapping, can help identify long-lived, deep-seated crustal structures that influenced the composition and location of magmatism, as well as facilitated and focused past and recent deformation and faulting. We also present isotopic binary mixing models for the entire history of Phanerozoic magmatism along the Zealandia Cordillera. Isotopic mixing models are consistent with mixing of various supracrustal, primitive lower crustal plutonic, and arc mantle sources, each with diverse ages and compositions. Mixing models support several episodes of major net-crustal growth and recycling. The isotopically defined crustal domains (including a distinct light δ18O value Eastern Isotope Domain) vary in size and composition from the Paleozoic – Mesozoic, suggesting that while lithospheric architecture had some influence on magmatism and related mineralization, lower-plate processes and their associated arc-tectonic geometry has also had a significant role in controlling magma compositions, and importantly the volume and flux of magmatic ‘flare-up’ events. Finally, published zircon O and Hf isotope data along the former southeast Gondwana margin enables strong correlations and comparisons across the now separated continental landmasses. The recognition of Permian rocks in Marie Byrd Land with light δ18O values support previous correlations between Zealandia’s outboard Median Batholith and the Amundsen Province.