Abstract

A new reference section of the Okhotsk seaside of Kamchatka in the Mitoga 2 River area is studied and dated for the first time (¹⁴C and ²³⁰Th/U). Sedimentary deposits were correlated with the previously known sections in the Khomutina‒Mitoga interfluve. It has been established that the sequence of “gray silts and clays” represents deposits of a large lake-type estuary, which began to swamp about 90–80 ka BP, and all sediments overlapping the silts began to form no earlier than 90 ka BP (second half of MIS 5). Deposits of a catastrophic collapse (clastic mass transport over about 100 km, area ≥1500 km², volume ≥15 km³), which descended from the Balaganchik Ridge about 90‒80 ka BP, were identified. Two main facies were established: dispersed basal layer (“moraine-type loam” sequence) and landslide proper sediments (conglomerates). Valleys of the Bystraya and Plotnikova rivers were blocked by a collapse, resulting in the formation of a large dammed lake. The catastrophic drainage of the lake could occur about 37 ka BP. Deposits related to the dam breakthrough are recorded between the Mitoga 2 River and Zuikovo Settlement on the Okhotsk coast.

中文翻译：

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巴拉甘奇克山脊的晚更新世灾难性滑坡：来自Mitoga 2参考断面（堪察加西部）的证据

摘要

首次研究了Mitoga 2河地区堪察加半岛鄂霍次克海沿岸的新参考断面，并首次标出了日期（¹⁴ C和²³⁰ Th / U）。沉积沉积物与Khomutina‒Mitoga河道之间的先前已知断层相关。已经确定，“灰色粉砂和粘土”的序列表示一个大型湖型河口的沉积物，开始在约90–80 ka BP沼泽化，所有与粉砂重叠的沉积物都在90 ka BP之前开始形成。 （MIS 5的后半部分）。灾难性坍塌的沉积物（碎屑大量运输超过100 km，面积≥1500km ²，体积≥15km ³）是从巴拉甘奇克山脊（Balaganchik Ridge）降落到约90‒80 ka BP。建立了两个主要相：分散的基底层（“冰a型壤土”序列）和滑坡适当的沉积物（砾岩）。比斯特拉亚河和普洛特尼科娃河的山谷被坍塌所阻塞，形成了一个大坝湖。该湖的灾难性排水可能发生在大约37 ka BP。在鄂霍次克沿岸的Mitoga 2河和Zuikovo定居点之间记录了与水坝突破相关的沉积物。