Nd and Sr isotopic signatures of metasedimentary rocks around the South Pacific margin and implications for their provenance
Nd and Sr isotopic signatures of metasedimentary rocks around the South Pacific margin and implications for their provenance
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南太平洋边缘变沉积岩的 Nd 和 Sr 同位素特征及其对物源的影响
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发表时间：
2005
期刊：
影响因子：
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通讯作者：
I. Millar
中科院分区：
文献类型：
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作者：
C. Adams;R. Pankhurst;R. Maas;I. Millar
摘要建立了一个包括c. 200个新的分析，介绍了从澳大利亚东南部、新西兰、西南极洲和南极半岛到南美洲南部的古生代和中生代变质沉积岩序列。结合U-Pb碎屑锆石年龄数据，这使得表征新西兰的火山岩，特别是在东部省，那里有一个进步，从最西端的火山/火山岩和增生起源与原始沉积物来源，最东端的火山岩与成熟的大陆沉积物输入。在南美洲南部、南极洲西部和南极洲半岛，类似的增生杂岩的Nd模式年龄主要反映了来自多个来源的沉积物质的混合，包括成熟的和幼年的。一个成熟的冈瓦纳大陆物源在活动边缘内侧的沉积盆地中占主导地位，特别是在古生代（西部省，新西兰，内陆西南极洲和西北阿根廷），并显着贡献前中生代沉积岩巴塔哥尼亚东部的安第斯山脉。沿着冈瓦纳大陆边缘，Nd系统的年轻（晚古生代至早中生代）增生杂岩沉积反映了年轻的源输入，特别是在斯科舍变质杂岩。许多加积杂岩矿床必然涉及重大的地壳改造。没有明显的南美相当于新西兰最西部的增生岩的原始起源。
Abstract An Nd-Sr isotope database, including c. 200 new analyses, is presented for Palaeozoic and Mesozoic metasedimentary successions extending through southeastern Australia, New Zealand, West Antarctica and the Antarctic Peninsula to southern South America. Combining with U-Pb detrital zircon age data, this enables characterization of New Zealand terranes, especially within the Eastern Province, where there is a progression from westernmost terranes of both volcanic/volcaniclastic and accretionary origin with primitive sediment sources, to easternmost terranes with mature continental sediment inputs. In southern South America, West Antarctica and the Antarctica Peninsula, similar accretionary complexes have Nd model ages principally reflecting mixing of sedimentary material from multiple sources, both mature and juvenile. A mature Gondwana continental provenance dominates in sedimentary basins inboard of the active margin, especially in the Palaeozoic (Western Province, New Zealand, interior West Antarctica and NW Argentina), and contributes significantly to pre-Mesozoic sedimentary rocks of Patagonia east of the Andes. Along the Gondwanaland margin, Nd systematics for younger (late Palaeozoic to early Mesozoic) accretionary complex metasediments reflect younger source inputs, notably in the Scotia metamorphic complex. Many of the accretionary complex deposits must involve significant crustal reworking. There is no apparent South American equivalent of the primitive provenance of the westernmost accretionary terranes of New Zealand.