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Detrital zircon age constraints on depositional history and provenance of the Murihiku Supergroup, Murihiku Terrane, North Island, New Zealand
Gondwana Research ( IF 7.2 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.gr.2020.06.011
C.J. Adams , H.J. Campbell

Abstract In the Murihiku Terrane of New Zealand, U-Pb detrital zircon ages in Murihiku Supergroup sandstones of Late Triassic, Jurassic and possibly earliest Cretaceous age have a marked youngest age component that is close to, and sometimes coincident with, established biostratigraphic ages, thus reflecting contemporary volcanism. However, youngest Huriwai Group samples yield 137–142 Ma zircon age components (earliest Early Cretaceous) in conflict with palynofloras that suggest only a latest Jurassic age. This is resolved if the age of the Jurassic/Cretaceous boundary is lowered to ca. 140 Ma. Older, reworked zircons are mainly Early Jurassic, Late Triassic and Late Permian reflecting an enduring exhumed magmatic arc source nearby. This might be in the adjacent Median Batholith but as a Murihiku sediment source its Jurassic, Triassic and Permian elements are not well-matched in terms of extent, age and bulk compositions. A connection between the Murihiku (proximal forearc) and Waipapa Composite (distal accretionary wedge) terranes is probable, with a common magmatic arc, speculatively situated in the New England Orogen, eastern Australia.

中文翻译:

碎屑锆石年龄对新西兰北岛 Murihiku Terrane Murihiku 超群沉积历史和来源的限制

摘要 在新西兰 Murihiku 地体中,晚三叠世、侏罗纪和可能最早的白垩纪 Murihiku 超群砂岩中的 U-Pb 碎屑锆石年龄具有显着的最年轻年龄成分,该年龄成分与已确定的生物地层年龄相近,有时与其重合,因此反映当代火山活动。然而,最年轻的 Huriwai Group 样品产生了 137-142 Ma 锆石年龄成分(最早的早白垩世),与仅表明侏罗纪晚期的孢粉菌群冲突。如果侏罗纪/白垩纪边界的年龄降低到大约 10 年,这个问题就解决了。140 马。较老的、重新加工的锆石主要是早侏罗世、晚三叠世和晚二叠世,反映了附近经久不衰的岩浆弧源。这可能在相邻的中基石基中,但作为 Murihiku 沉积物的来源,它的侏罗纪,三叠纪和二叠纪元素在范围、年龄和整体组成方面并不匹配。Murihiku(近端前弧)和 Waipapa 复合(远端增生楔)地体之间可能存在连接,具有共同的岩浆弧,推测位于澳大利亚东部的新英格兰造山带。
更新日期:2020-11-01
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