Possible conditions and the formation time of the Chukchi Plateau pockmarks

Abstract

The study of the bottom sediments accumulated during the last 60-65 ka in the pockmark craters of the Chukchi Plateau in the Arctic Ocean showed that their composition and lithostratigraphy in general are similar to those of the background areas. A specific feature is the presence of sedimentary interlayers and horizons with signs of gravitational stirring, carbonate mineralization, and accumulation under H 2 S contam ination conditions. The micropaleontological remains found in the pockmark sediments accumulated during the glacial periods are represented by redeposited species from Paleozoic, Mesozoic, and Cenozoic deposits, which are locally exposed in the pockmark walls. It was concluded that the pockmarks were formed under the influence of pulsed fluid flows. The present day topography of the pockmarks was formed at the last stage of active defluidization (35-20 ka ago).

Fluidogenic landforms on the Arctic shelves

“…-giant craters and domal rises of the shelf edge: 1a -after[Waage et al, 2019]; 1б -after[Waage et al, 2020]; 1в -after[Astakhov et al, 2014]; 2 -areas of gas manifestations in bottom sediments and water column; 3 -areas of pockmarks: 3a -according to; 3б -according to; 3в -according to[Tasianas et al, 2018]; 3г -according to [Salt..., 2022]; 4 -areas of pingo-like features: 4a -according to[Semenov et al, 2020;; 4б -according toShakhova et al, 2015]; 5-8 -fluidogenic forms and gas manifestations based on the results of investigations on the R/V "Akademik Nikolai Strakhov" with participation of the authors: 5 -areas of gas manifestations in water column and the section of bottom sediments; 6 -areas of pockmarks and associated gas manifestations in water column and the section of sediments; 7 -areas of pockmarks, pingolike features and gas manifestations in water column and the sediment section; 8 -areas of pockmarks without accompanying gas manifestations; 9-10 -stations for core sampling and measurements of the temperature of bottom sediments according to]: 9 -with positive; 10 -with negative temperatures of bottom sediments; 11-12 -areas of surveys with the fluidogenic bottom forms and gas shows described in the articles: 11 -; 12 -; 13 -area of pockmarks mapping in; 14 -boundary of the stability zone of deep-sea gas hydrates (isobaths 300-450 m) according to; 15 -boundary of distribution of subaqueous permafrost rocks according to the model data; 16 -northern limit of subaquatic permafrost on the Laptev Sea shelf based on the results of analysis of reflected wave velocities on sections obtained by the common depth point method …”