Abstract The Cretaceous marks an episode of enhanced magmatism, sedimentation and tectonic processes along the entire proto-Pacific convergent margin of West Gondwana. Cretaceous magmatism across the Antarctic Peninsula is dominated by the intrusive Lassiter Coast intrusive suite which developed as episodic ‘flare-up’ events during the mid-Cretaceous, at a time of increased convergence. Volcanic rocks of this age are poorly defined, as a consequence of limited field observations and an absence of accurate geochronology. Recent field mapping, combined with unpublished field observations has identified a region >10,000 km2 of dominantly subaerial rhyolitic pyroclastic and epiclastic successions from northern Palmer Land of the Antarctic Peninsula. Volcanic successions up to 1500 m in thickness consist of dominantly silicic ignimbrites, lavas, heterolithic breccias and lahar deposits, fed by caldera-forming eruptions. The volcanic rocks of this region were widely considered to be Early Cretaceous in age based on field relationships and early geochronology. New U-Pb zircon ages identify three distinct volcanic episodes during the Late Cretaceous/Early Cenozoic at ~108 Ma, ~93 Ma and ~64 Ma. Lu-Hf data indicate significant proportions of ancient crust in the petrogenesis of the volcanic rocks and the slightly negative eHf values are consistent with a mid-position (~120 km) within the magmatic arc, relative to more juvenile compositions close to the trench.

中文翻译：

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南极半岛帕尔默地的白垩纪弧火山活动：锆石 U-Pb 年代学、地球化学、分布和现场关系

摘要 白垩纪标志着整个西冈瓦纳原始太平洋辐合边缘的岩浆作用、沉积作用和构造作用增强。横跨南极半岛的白垩纪岩浆活动主要是由侵入性的 Lassiter Coast 侵入岩套控制的，这些岩浆岩在白垩纪中期，在辐合增加的时候发展为偶发的“爆发”事件。由于实地观测有限和缺乏准确的地质年代学，这个时代的火山岩定义不明确。最近的实地测绘，结合未发表的实地观察，已经确定了一个大于 10,000 平方公里的区域，该区域主要来自南极半岛帕默地北部的流纹岩火山碎屑和外碎屑岩层。厚度达 1500 m 的火山岩层主要由硅质凝灰岩、熔岩、由形成火山口的喷发形成的异质角砾岩和火山岩沉积物。根据现场关系和早期地质年代学，该地区的火山岩在年龄上被广泛认为是早白垩世。新的 U-Pb 锆石年龄确定了晚白垩世/早新生代期间~108 Ma、~93 Ma 和~64 Ma 的三个不同的火山事件。Lu-Hf 数据表明，在火山岩的岩石形成过程中，古地壳占很大比例，并且相对于靠近海沟的更年轻的成分，eHf 值略微为负值与岩浆弧内的中间位置（~120 公里）一致。新的 U-Pb 锆石年龄确定了晚白垩世/早新生代期间~108 Ma、~93 Ma 和~64 Ma 的三个不同的火山事件。Lu-Hf 数据表明，在火山岩的岩石形成过程中，古地壳占很大比例，并且相对于靠近海沟的更年轻的成分，eHf 值略微为负值与岩浆弧内的中间位置（~120 公里）一致。新的 U-Pb 锆石年龄确定了晚白垩世/早新生代期间~108 Ma、~93 Ma 和~64 Ma 的三个不同的火山事件。Lu-Hf 数据表明，在火山岩的岩石形成过程中，古地壳占很大比例，并且相对于靠近海沟的更年轻的成分，eHf 值略微为负值与岩浆弧内的中间位置（~120 公里）一致。