TY - JOUR

T1 - Precambrian–Cambrian Transition at the Igarka Uplift (Northwestern Siberian Platform)

AU - Marusin, V.V.

AU - Kochnev, B.B.

AU - Karlova, G.A.

AU - Izokh, O.P.

AU - Sarsembaev, Zh.A.

AU - Иванова, Наталья Александровна

N1 - This study was supported by the Russian Foundation for Basic Research (grant No. 20-05-00101; fieldworks) and the Russian Science Foundation (grant No. 21-17-00052; ana-lytical study). The work is coordinated by the Basic Research Program of the Russian Academy of Sciences FWZZ-2022-0002. We thank S.V. Saraev (Trofimuk Institute of Petroleum Geology and Geophysics) for his help during the fieldworks and I.V. Korovnikov (Trofimuk Institute of Petroleum Geology and Geophysics), who identified some problematic fossils and found paleontologic material from the Kulyumbe River published in (Sipin, 2001). We also thank E.V. Bushuev (Novosibirsk Branch of All-Russian Research Geological Oil Institute) for the information on stratigraphic distribution of trilobites in the KhS-1 well section. The authors are grateful to the reviewers D.P. Gladkochub (Institute of the Earth’s Crust, Irkutsk) and D.V. Grazhdankin (Trofimuk Institute of Petroleum Geology and Geophysics) for the valuable comments, which improved the manuscript considerably.

PY - 2023/6/1

Y1 - 2023/6/1

N2 - The Precambrian–Cambrian transition is one of the most fundamental evolutionary turnovers in the Earth’s history. How-ever, in many cases precise identification and correlation of this crucial boundary in lithologically contrasting sections is complicated, even if the whole spectrum of biostratigraphic and chemostratigraphic methods is applied. The Precambrian–Cambrian transitional strata of the Igarka Uplift (Sukharikha Formation) perfectly illustrate this problem. This unit has arguably one of the most detailed carbonate carbon isotope curves for this time interval (at least within the Siberian Platform). However, an extremely poor paleontological record previously reported from the Sukharikha Formation makes identification of major stratigraphic boundaries highly debatable. We present a detailed study of the Sukharikha and overlying Krasnyi Porog formations in three sections (Sukharikha River, Kulyumbe River, and Khantaisko-Sukhotungusskaya-1 well). Our chemostratigraphic and biostratigraphic data provide a correlation basis for these sections and identify the Cambrian boundary in terms of both the International Chronostratigraphic Chart and General Stratigraphic Scale of Russia. We show that lithologic boundaries and levels of the local first appearance of Tommotian small skeletal fossils are diachronous within the Igarka paleobasin. The latter is putatively caused by paleoecology of the early Cambrian biota and by taphonomic factors. Our data specify the location of the Tommotian Stage (sensu lato)/Cambrian Stage 2 boundary in other key Precambrian–Cambrian transitional sections of the Siberian Platform.

AB - The Precambrian–Cambrian transition is one of the most fundamental evolutionary turnovers in the Earth’s history. How-ever, in many cases precise identification and correlation of this crucial boundary in lithologically contrasting sections is complicated, even if the whole spectrum of biostratigraphic and chemostratigraphic methods is applied. The Precambrian–Cambrian transitional strata of the Igarka Uplift (Sukharikha Formation) perfectly illustrate this problem. This unit has arguably one of the most detailed carbonate carbon isotope curves for this time interval (at least within the Siberian Platform). However, an extremely poor paleontological record previously reported from the Sukharikha Formation makes identification of major stratigraphic boundaries highly debatable. We present a detailed study of the Sukharikha and overlying Krasnyi Porog formations in three sections (Sukharikha River, Kulyumbe River, and Khantaisko-Sukhotungusskaya-1 well). Our chemostratigraphic and biostratigraphic data provide a correlation basis for these sections and identify the Cambrian boundary in terms of both the International Chronostratigraphic Chart and General Stratigraphic Scale of Russia. We show that lithologic boundaries and levels of the local first appearance of Tommotian small skeletal fossils are diachronous within the Igarka paleobasin. The latter is putatively caused by paleoecology of the early Cambrian biota and by taphonomic factors. Our data specify the location of the Tommotian Stage (sensu lato)/Cambrian Stage 2 boundary in other key Precambrian–Cambrian transitional sections of the Siberian Platform.

KW - Cambrian

KW - chemostratigraphy

KW - Ediacaran

KW - Siberian Platform

KW - small skeletal fossils

KW - stratigraphy

UR - https://www.scopus.com/record/display.uri?eid=2-s2.0-85168145056&origin=inward&txGid=a32425dbbc4997077f888852c62d56e2

UR - https://www.mendeley.com/catalogue/4d623b8c-c4dc-30b6-98c3-b9db792737e7/

U2 - 10.2113/RGG20224523

DO - 10.2113/RGG20224523

M3 - Article

VL - 64

SP - 682

EP - 697

JO - Russian Geology and Geophysics

JF - Russian Geology and Geophysics

SN - 1068-7971

IS - 6

ER -