Peperites in the Permian Tarim large igneous province in Northwest China and their constraints on the local eruption environments

Peperites 是岩浆和 unconsolidated 沉积混合产生的 volcaniclastic 材料的特殊类型。他们直接表明火山作用和沉积的同时期性，并且因此，他们能被用来在暴烈的爆发期间抑制本地 paleoenvironments。我们在二叠的 Tarim 大火的省(TLIP ) 的西北露头(Inggan-Kalpin 区域) 的更低的顺序识别了 peperites，西北中国。在 Inggan，短而粗的 peperites 在在第二个爆发阶段产生的熔岩流动的底被观察。这种 peperites 被在易碎的破碎机制岩浆熄灭产生。当时在 Kalpin，两第二并且第四个爆发阶段在熔岩流动的底保存了 peperites。不仅短而粗而且 fluidal peperites 能在 Kalpin 被观察。fluidal peperites 在蒸汽被产生从冷沉积和避免的直接热的吃惊拍摄岩浆，它绝缘，因此保持了岩浆的 fluidal 体形。所有被海底的碳酸盐这些 peperites 招待。在在一样的爆发阶段产生，但是在 Kaipaizileike 定位了的熔岩序列， 15 km 东方到 Inggan，当 peperites 是不在的时，陆上的洪水暗岩发展了，暗示在 Kaipaizileike 和 Inggan-Kalpin 区域之间的 paleoenvironmental 转变。从观察 peperites， TLIP 熔岩流动，和更低的二叠的沉积阶层的聚在一起的信息，我们精确抑制了空间分发和 TLIP 的早阶段的沉积外形的时间的进化。作为结果，二海洋的违反被识别。第一违反发生了与第二个爆发阶段同时期。从潜水艇的转变到地面上在 Kaipaizileike 和 Inggan 之间被定位。第二违反发生了与同时期向前从潜水艇的爆发阶段，和转变到地面上发生在 Inggan 和 Kalpin 之间。

Peperites are special kinds of volcaniclastic materials generated by mingling of magma and unconsolidated sediments. They directly demonstrate the contemporaneity of volcanism and sedimentation, and hence they can be used to constrain the local paleoenvironments during volcanic eruptions. We identified peperites in the lower sequence of the northwest outcrops（Inggan-Kalpin area） of Permian Tarim large igneous province（TLIP）, Northwest China. In Inggan, blocky peperites were observed at the base of lava flows generated in the second eruption phase. This kind of peperites is generated by quenching of magma in a brittle fragmentation mechanism. While in Kalpin, both the second and the fourth eruption phases preserved peperites in the base of lava flows. Not only blocky but also fluidal peperites can be observed in Kalpin. The fluidal peperites were generated in vapor films, which insulated the magmas from cold sediments and avoided direct thermal shock, and therefore kept the fluidal forms of magma. All of these peperites are hosted by submarine carbonates. In lava sequences generated in the same eruption phases but located in Kaipaizileike, ~15 km east to Inggan, terrestrial flood basalts developed while peperites are absent, implying a paleoenvironmental transition between Kaipaizileike and Inggan-Kalpin area. Gathering information from observed peperites, TLIP lava flows, and the Lower Permian sedimentary strata, we precisely constrained the spatial distribution and temporal evolution of sedimentary facies of the early stage of TLIP. As a result, two marine transgressions were identified. The first transgression occurred contemporaneous with the second eruption phase. The transition from submarine to subaerial is located between Kaipaizileike and Inggan. The second transgression occurred contemporaneous with the forth eruption phase, and the transition from submarine to subaerial occurred between Inggan and Kalpin.