Abstract This paper provides new trace element and Sr-Nd-Hf-Pb-O isotope data on Neoproterozoic to Phanerozoic mid to upper crustal lithologies of the Andean basement in central Chile and western Argentina (33°-35°S; 69°-72°W). It also provides additional data on trench sediments being subducted offshore the northern segment of the Southern Volcanic Zone in Chile. Neoproterozoic metamorphic and igneous rocks from the Guarguaraz complex (Argentina; 33.6°S, 69.5°W), when back corrected to 350 Ma, display a narrow range in 87Sr/86Sri (0.713–0.718), 143Nd/144Ndi (0.5118–0.5121), eNdi (−8.1 to −1.1), eHfi (−11.4 to +1.2) and δ18O (9–13‰). Nd model ages (TDM = 1.08–1.65 Ga) for the Guarguaraz complex points to a Mesoproterozoic crustal residence age for these rocks. Metasedimentary rocks from the Carboniferous accretionary prism in central Chile (~34°S) overlap with these ranges, but differ by having lower initial 87Sr/86Sri (0.7052–0.7093) and higher δ18O (14–17‰). The Guarguaraz metamorphic and igneous rocks, when back corrected to 350 Ma, have similar Pb isotope ratios than the Chilean Carboniferous metasedimentary rocks (206Pb/204Pbi = 17.58–18.52 vs. 18.33–18.46; 207Pb/204Pbi = 15.50–15.64 vs. ~15.64; 208Pb/204Pbi = 37.70–38.36 vs. 37.98–38.18). Two Guarguaraz samples are shifted towards less radiogenic Pb isotope ratios, similar to samples representative of the Cuyania basement. This suggests that Chilenia hosts at least two geochemical components: (1) a component with unradiogenic Pb isotopes, similar to the Proterozoic Cuyania basement, and (2) a component with more radiogenic Pb isotopes, similar to Chilean Phanerozoic metasedimentary and igneous rocks. The ranges in Pb isotope ratios for the Chilean Mesozoic (206Pb/204Pbi = 18.44–19.86; 207Pb/204Pbi = 15.59–15.69; 208Pb/204Pbi = 38.30–40.30) and Miocene (206Pb/204Pbi = 18.43–18.57; 207Pb/204Pbi = 15.58–15.60; 208Pb/204Pbi = 38.33–38.46) igneous rocks are similar to those of the accretionary prism. The Mesozoic and Miocene intrusive rocks are characterized by low 87Sr/86Sri (0.704–0.708 and ~0.704, respectively) and high eNdi (−6.2 to +4.0 and + 3.9 to +5.9, respectively) and eHfi (+7.0 to +12.7 and + 8.5 to +10.8, respectively). They can be divided into two groups. Group (1), consisting exclusively of Mesozoic samples, has negative eNdi, 87Sr/86Sri > 0.706, elevated e.g., Ba/Th, Nb/Yb, Zr/Y and lower Nb/La, reflecting derivation from enriched (most likely overriding crust or mantle) material. Group (2), consisting of Mesozoic and Miocene rocks, has positive eNdi, eHfi, and lower initial 87Sr/86Sri than group (1) reflecting depleted mantle melts addition to the crust. Finally, Sr-Nd-O isotopic compositions of the trench sediments at latitude 33°-33.3°S are almost identical to those at latitude 35°-40°S, indicating a relative homogeneous material input along the SVZ, although there are subtle differences in REE and Pb isotopic compositions. Based on Nd–Hf isotopes, trench sediments offshore Chile (eNd> +1; eHf > +2) and offshore Peru (eNd

中文翻译：

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Sr-Nd-Pb-Hf-O同位素对智利中部和阿根廷西部新元古代至中新世上地壳和海沟沉积物（33°-35°S）的同位素约束

摘要 本文提供了智利中部和阿根廷西部 (33°-35°S; 69°-72) 安第斯基底新元古代至显生宙中上地壳岩性的新微量元素和 Sr-Nd-Hf-Pb-O 同位素数据。 °W)。它还提供了关于在智利南部火山带北段近海俯冲的海沟沉积物的额外数据。来自 Guarguaraz 杂岩体（阿根廷；33.6°S，69.5°W）的新元古代变质岩和火成岩，当回校正至 350 Ma 时，在 87Sr/86Sri (0.713-0.718), 143Nd/151112-1.0.143Nd/144Ndi (0.715) 显示一个狭窄的范围, eNdi (-8.1 to -1.1), eHfi (-11.4 to +1.2) 和 δ18O (9–13‰)。Guarguaraz 复合体的 Nd 模型年龄（TDM = 1.08-1.65 Ga）表明这些岩石属于中元古代地壳居住年龄。来自智利中部石炭纪增生棱柱体的变质沉积岩 (~34°S) 与这些范围重叠，但不同之处在于初始 87Sr/86Sri (0.7052–0.7093) 和更高的 δ18O (14–17‰)。Guarguaraz 变质岩和火成岩，当回校正到 350 Ma 时，具有与智利石炭纪变质沉积岩相似的 Pb 同位素比（206Pb/204Pbi = 17.58–18.52 vs. 18.33–18.46；207Pb/215.56Pb = ~15.46Pb） ；208Pb/204Pbi = 37.70–38.36 与 37.98–38.18）。两个 Guarguaraz 样品转向放射性较低的 Pb 同位素比率，类似于代表 Cuyania 基底的样品。这表明智利至少拥有两种地球化学成分：（1）具有非放射性铅同位素的成分，类似于元古代Cuyania基底，以及（2）具有更多放射性铅同位素的成分，类似于智利显生宙变沉积岩和火成岩。智利中生代 Pb 同位素比的范围（206Pb/204Pbi = 18.44–19.86；207Pb/204Pbi = 15.59–15.69；208Pb/204Pbi = 38.30–40.32；4Pb/4Pb/2108P/4Pb/2108P/4Pb/2108P） 15.58-15.60；208Pb/204Pbi = 38.33-38.46）火成岩与增生棱柱相似。中生代和中新世侵入岩的特征是低 87Sr/86Sri（分别为 0.704–0.708 和 ~0.704）和高 eNdi（分别为 -6.2 到 +4.0 和 +3.9 到 +5.9）和 eHfi（分别为 +7.0 到 +12.7 和+ 8.5 到 +10.8，分别）。他们可以分为两组。组 (1)，仅由中生代样品组成，具有负的 eNdi，87Sr/86Sri > 0.706，升高，例如 Ba/Th、Nb/Yb、Zr/Y 和较低的 Nb/La，反映来自富集（最有可能是上覆地壳或地幔）物质的衍生。由中生代和中新世岩石组成的组 (2) 具有正的 eNdi、eHfi 和比组 (1) 更低的初始 87Sr/86Sri，反映了地壳中添加的耗尽地幔熔体。最后，纬度 33°-33.3°S 海沟沉积物的 Sr-Nd-O 同位素组成与纬度 35°-40°S 几乎相同，表明沿 SVZ 的物质输入相对均匀，尽管存在细微差异REE 和 Pb 同位素组成。基于 Nd–Hf 同位素，智利近海 (eNd> +1；eHf > +2) 和秘鲁近海 (eNd 纬度 33°-33.3°S 海沟沉积物的 Sr-Nd-O 同位素组成与纬度 35°-40°S 几乎相同，表明沿 SVZ 的物质输入相对均匀，尽管 REE 存在细微差异和铅同位素组成。基于 Nd–Hf 同位素，智利近海 (eNd> +1；eHf > +2) 和秘鲁近海 (eNd 纬度 33°-33.3°S 海沟沉积物的 Sr-Nd-O 同位素组成与纬度 35°-40°S 几乎相同，表明沿 SVZ 的物质输入相对均匀，尽管 REE 存在细微差异和铅同位素组成。基于 Nd–Hf 同位素，智利近海 (eNd> +1；eHf > +2) 和秘鲁近海 (eNd