3 research outputs found
Ooidal ironstones in the Meso-Cenozoic sequences in western Siberia: assessment of formation processes and relationship with regional and global earth processes
This study investigates the process of formation of ooidal ironstones in the Upper Cretaceous-Paleogene succession in western Siberia. The formation of such carbonate-based ironstones is a continuing problem in sedimentary geology, and in this study, we use a variety of data and proxies assembled from core samples to develop a model to explain how the ooidal ironstones formed. Research on pyrite framboids and geochemical redox proxies reveals three intervals of oceanic hypoxia during the deposition of marine ooidal ironstones in the Late Cretaceous to the Early Paleogene Bakchar ironstone deposit in western Siberia; the absence of pyrite indicates oxic conditions for the remaining sequence. While goethite formed in oxic depositional condition, chamosite, pyrite and siderite represented hypoxic seawater. Euhedral pyrite crystals form through a series of transition originating from massive aggregate followed by normal and polygonal framboid. Sediments associated with goethite-chamosite ironstones, encompassing hypoxic intervals exhibit positive cerium, negative europium, and negative yttrium anomalies. Mercury anomalies, associated with the initial stages of hypoxia, correlate with global volcanic events. Redox sensitive proxies and ore mineral assemblages of deposits reflect hydrothermal activation. Rifting and global volcanism possibly induced hydrothermal convection in the sedimentary cover of western Siberia, and released iron-rich fluid and methane in coastal and shallow marine environments. This investigation, therefore, reveals a potential geological connection between Large Igneous Provinces (LIPs), marine hypoxia, rifting and the formation of ooidal ironstones in ancient West Siberian Sea
Ooidal ironstones in the Meso-Cenozoic sequences in western Siberia: assessment of formation processes and relationship with regional and global earth processes
This study investigates the process of formation of ooidal ironstones in the Upper Cretaceous-Paleogene succession in western Siberia. The formation of such carbonate-based ironstones is a continuing problem in sedimentary geology, and in this study, we use a variety of data and proxies assembled from core samples to develop a model to explain how the ooidal ironstones formed. Research on pyrite framboids and geochemical redox proxies reveals three intervals of oceanic hypoxia during the deposition of marine ooidal ironstones in the Late Cretaceous to the Early Paleogene Bakchar ironstone deposit in western Siberia; the absence of pyrite indicates oxic conditions for the remaining sequence. While goethite formed in oxic depositional condition, chamosite, pyrite and siderite represented hypoxic seawater. Euhedral pyrite crystals form through a series of transition originating from massive aggregate followed by normal and polygonal framboid. Sediments associated with goethite-chamosite ironstones, encompassing hypoxic intervals exhibit positive cerium, negative europium, and negative yttrium anomalies. Mercury anomalies, associated with the initial stages of hypoxia, correlate with global volcanic events. Redox sensitive proxies and ore mineral assemblages of deposits reflect hydrothermal activation. Rifting and global volcanism possibly induced hydrothermal convection in the sedimentary cover of western Siberia, and released iron-rich fluid and methane in coastal and shallow marine environments. This investigation, therefore, reveals a potential geological connection between Large Igneous Provinces (LIPs), marine hypoxia, rifting and the formation of ooidal ironstones in ancient West Siberian Sea
Identifying sources of organic carbon in surface sediments of Laptev Sea shelf using a Rock-Eval approach
ΠΠΊΡΡΠ°Π»ΡΠ½ΠΎΡΡΡ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΠΎΠ±ΡΡΠ»ΠΎΠ²Π»Π΅Π½Π° Π½Π΅ΠΎΠ±Ρ
ΠΎΠ΄ΠΈΠΌΠΎΡΡΡΡ Π²ΡΠ΅ΡΡΠΎΡΠΎΠ½Π½Π΅Π³ΠΎ ΠΈΠ·ΡΡΠ΅Π½ΠΈΡ ΠΏΡΠΎΡΠ΅ΡΡΠΎΠ², ΠΎΡΠ²Π΅ΡΡΡΠ²Π΅Π½Π½ΡΡ
Π·Π° ΠΈΠ·ΠΌΠ΅Π½Π΅Π½ΠΈΡ Π±ΠΈΠΎΠ³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ΅ΠΆΠΈΠΌΠ° Π°ΡΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ΅Π³ΠΈΠΎΠ½Π°. Π£Π²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠ΅ ΡΠ΅ΠΌΠΏΠΎΠ² Π΄Π΅Π³ΡΠ°Π΄Π°ΡΠΈΠΈ ΠΏΡΠΈΠ±ΡΠ΅ΠΆΠ½ΠΎΠΉ ΠΈ ΠΏΠΎΠ΄Π²ΠΎΠ΄Π½ΠΎΠΉ ΠΌΠ΅ΡΠ·Π»ΠΎΡΡ Π½Π° ΠΠΎΡΡΠΎΡΠ½ΠΎ-Π‘ΠΈΠ±ΠΈΡΡΠΊΠΎΠΌ ΡΠ΅Π»ΡΡΠ΅ ΠΏΡΠΈΠ²ΠΎΠ΄ΠΈΡ ΠΊ Π²ΠΎΠ²Π»Π΅ΡΠ΅Π½ΠΈΡ Π² ΡΠΎΠ²ΡΠ΅ΠΌΠ΅Π½Π½ΡΠΉ Π±ΠΈΠΎΠ³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΠΉ ΡΠΈΠΊΠ» Π±ΠΎΠ»ΡΡΠΎΠ³ΠΎ ΠΎΠ±ΡΠ΅ΠΌΠ° ΡΠ΅ΠΌΠΎΠ±ΠΈΠ»ΠΈΠ·ΠΎΠ²Π°Π½Π½ΠΎΠ³ΠΎ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ ΡΠ³Π»Π΅ΡΠΎΠ΄Π°. ΠΠ·ΡΡΠ΅Π½ΠΈΠ΅ ΠΎΡΠΎΠ±Π΅Π½Π½ΠΎΡΡΠ΅ΠΉ Π΅Π³ΠΎ ΡΡΠ°Π½ΡΠΏΠΎΡΡΠ° ΠΈ ΠΏΡΠ΅ΠΎΠ±ΡΠ°Π·ΠΎΠ²Π°Π½ΠΈΡ Π² ΡΠΈΡΡΠ΅ΠΌΠ΅ ΡΡΡΠ°-ΡΠ΅Π»ΡΡ ΠΈΠ³ΡΠ°Π΅Ρ Π²Π°ΠΆΠ½ΡΡ ΡΠΎΠ»Ρ Π΄Π»Ρ ΠΎΡΠ΅Π½ΠΊΠΈ ΡΡΠ½ΠΊΡΠΈΠΎΠ½ΠΈΡΠΎΠ²Π°Π½ΠΈΡ ΠΊΡΠ°ΠΉΠ½Π΅ Ρ
ΡΡΠΏΠΊΠΎΠΉ Π°ΡΠΊΡΠΈΡΠ΅ΡΠΊΠΎΠΉ ΡΠΊΠΎΡΠΈΡΡΠ΅ΠΌΡ. Π¦Π΅Π»Ρ: ΠΈΠ·ΡΡΠ΅Π½ΠΈΠ΅ Π³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠΈΡ
Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊ ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π°, ΠΏΡΠΎΡΠ»Π΅ΠΆΠΈΠ²Π°Π΅ΠΌΡΡ
ΠΏΠΎ ΠΏΡΠΎΡΠΈΠ»Ρ ΠΎΡ Π±Π΅ΡΠ΅Π³ΠΎΠ²ΠΎΠΉ Π·ΠΎΠ½Ρ ΠΊ ΠΊΠΎΠ½ΡΠΈΠ½Π΅Π½ΡΠ°Π»ΡΠ½ΠΎΠΌΡ ΡΠΊΠ»ΠΎΠ½Ρ ΠΌΠΎΡΡ ΠΠ°ΠΏΡΠ΅Π²ΡΡ
Ρ ΠΏΡΠΈΠΌΠ΅Π½Π΅Π½ΠΈΠ΅ΠΌ ΠΌΠ΅ΡΠΎΠ΄Π° Rock-Eval ΠΈ ΠΎΡΠ΅Π½ΠΊΠ° ΠΈΡ
Π²Π·Π°ΠΈΠΌΠΎΡΠ²ΡΠ·ΠΈ Ρ Π»ΠΈΡΠΎΠ»ΠΎΠ³ΠΈΡΠ΅ΡΠΊΠΈΠΌΠΈ ΡΠ²ΠΎΠΉΡΡΠ²Π°ΠΌΠΈ Π²ΠΌΠ΅ΡΠ°ΡΡΠΈΡ
ΠΎΡΠ°Π΄ΠΊΠΎΠ². ΠΠ±ΡΠ΅ΠΊΡΠΎΠΌ ΠΈΡΡΠ»Π΅Π΄ΠΎΠ²Π°Π½ΠΈΡ ΡΠ²ΠΈΠ»ΠΈΡΡ ΠΏΡΠΎΠ±Ρ Π΄ΠΎΠ½Π½ΡΡ
ΠΎΡΠ°Π΄ΠΊΠΎΠ², Π²Π·ΡΡΡΠ΅ Ρ ΠΏΠΎΠ²Π΅ΡΡ
Π½ΠΎΡΡΠ½ΠΎΠ³ΠΎ Π³ΠΎΡΠΈΠ·ΠΎΠ½ΡΠ° (0-2 ΡΠΌ). ΠΡΠ±ΠΎΡ ΠΏΡΠΎΠ± ΠΏΡΠΎΠ²ΠΎΠ΄ΠΈΠ»ΡΡ Π² ΠΌΠΎΡΡΠΊΠΈΡ
Π°ΡΠΊΡΠΈΡΠ΅ΡΠΊΠΈΡ
ΡΠΊΡΠΏΠ΅Π΄ΠΈΡΠΈΡΡ
2018-2019 Π³Π³. Π½Π° ΠΠΠ‘ Β«ΠΠΊΠ°Π΄Π΅ΠΌΠΈΠΊ ΠΡΡΠΈΡΠ»Π°Π² ΠΠ΅Π»Π΄ΡΡΒ». Π Π΅Π·ΡΠ»ΡΡΠ°ΡΡ. ΠΠ° ΠΎΡΠ½ΠΎΠ²Π΅ ΡΠ΅Π·ΡΠ»ΡΡΠ°ΡΠΎΠ² ΠΏΠΈΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π°Π½Π°Π»ΠΈΠ·Π° Π΄Π°Π½Π° Π³Π΅ΠΎΡ
ΠΈΠΌΠΈΡΠ΅ΡΠΊΠ°Ρ Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΡΡΠΈΠΊΠ° ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π°, ΡΠΎΠ΄Π΅ΡΠΆΠ°ΡΠ΅Π³ΠΎΡΡ Π² Π΄ΠΎΠ½Π½ΡΡ
ΠΎΡΠ°Π΄ΠΊΠ°Ρ
ΠΌΠΎΡΡ ΠΠ°ΠΏΡΠ΅Π²ΡΡ
. ΠΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ΅ Π²Π΅ΡΠ΅ΡΡΠ²ΠΎ, ΡΠΊΡΠΏΠΎΡΡΠΈΡΡΠ΅ΠΌΠΎΠ΅ Ρ ΡΠ΅ΡΠ½ΡΠΌ ΡΡΠΎΠΊΠΎΠΌ ΠΈ ΠΏΡΠΎΠ΄ΡΠΊΡΠ°ΠΌΠΈ Π±Π΅ΡΠ΅Π³ΠΎΠ²ΠΎΠΉ ΡΡΠΎΠ·ΠΈΠΈ, Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠΈΠ·ΡΠ΅ΡΡΡ ΠΎΡΠ½ΠΎΡΠΈΡΠ΅Π»ΡΠ½ΠΎ Π½ΠΈΠ·ΠΊΠΈΠΌ ΠΊΠΈΡΠ»ΠΎΡΠΎΠ΄Π½ΡΠΌ (OI) ΠΈ Π²ΠΎΠ΄ΠΎΡΠΎΠ΄Π½ΡΠΌ (HI) ΠΈΠ½Π΄Π΅ΠΊΡΠ°ΠΌΠΈ Π² ΠΏΡΠΈΠ±ΡΠ΅ΠΆΠ½ΠΎΠΉ Π·ΠΎΠ½Π΅ ΠΈ Π½Π° Π³Π»ΡΠ±ΠΈΠ½Π°Ρ
Π΄ΠΎ Π½Π΅ΡΠΊΠΎΠ»ΡΠΊΠΈΡ
Π΄Π΅ΡΡΡΠΊΠΎΠ² ΠΌΠ΅ΡΡΠΎΠ². Π ΡΠ°ΠΉΠΎΠ½Π΅ ΡΡΠ΅Π΄Π½Π΅Π³ΠΎ ΡΠ΅Π»ΡΡΠ° ΡΡΡΠ΅ΡΡΠ²Π΅Π½Π½ΠΎΠ΅ Π²Π»ΠΈΡΠ½ΠΈΠ΅ Π½Π° ΡΠΎΡΡΠ°Π² ΠΎΡΠ³Π°Π½ΠΈΡΠ΅ΡΠΊΠΎΠ³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π°, ΠΏΠΎ Π²ΡΠ΅ΠΉ Π²ΠΈΠ΄ΠΈΠΌΠΎΡΡΠΈ, ΠΎΠΊΠ°Π·ΡΠ²Π°Π΅Ρ ΡΠ½ΠΎΡ ΠΎΡΠ°Π΄ΠΎΡΠ½ΠΎΠ³ΠΎ Π²Π΅ΡΠ΅ΡΡΠ²Π° Ρ ΠΠΎΠ²ΠΎΡΠΈΠ±ΠΈΡΡΠΊΠΈΡ
ΠΎΡΡΡΠΎΠ²ΠΎΠ², Π³Π΄Π΅ Π°ΠΊΡΠΈΠ²Π½ΠΎ Π΄Π΅ΠΉΡΡΠ²ΡΡΡ ΡΠ΅ΡΠΌΠΎΠ°Π±ΡΠ°Π·ΠΈΠΎΠ½Π½ΡΠ΅ ΠΏΡΠΎΡΠ΅ΡΡΡ (ΡΠ½ΠΈΠΆΠ΅Π½ΠΈΠ΅ Π·Π½Π°ΡΠ΅Π½ΠΈΠΉ HI ΠΈ ΡΠ²Π΅Π»ΠΈΡΠ΅Π½ΠΈΠ΅ OI). ΠΡΡΠΊΠ°Π·Π°Π½ΠΎ ΠΏΡΠ΅Π΄ΠΏΠΎΠ»ΠΎΠΆΠ΅Π½ΠΈΠ΅, ΡΡΠΎ Π΄Π»Ρ ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ², Π²ΡΠ½ΠΎΡΠΈΠΌΡΡ
ΡΠ΅ΡΠ½ΡΠΌ ΡΡΠΎΠΊΠΎΠΌ, ΠΈ ΠΏΡΠΎΠ΄ΡΠΊΡΠΎΠ² ΡΡΠΎΠ·ΠΈΠΈ Π±Π΅ΡΠ΅Π³ΠΎΠ² Ρ
Π°ΡΠ°ΠΊΡΠ΅ΡΠ½Ρ ΡΠ°Π·Π»ΠΈΡΠ½ΡΠ΅ ΠΏΠΈΡΠΎΠ»ΠΈΡΠΈΡΠ΅ΡΠΊΠΈΠ΅ ΠΏΠ°ΡΠ°ΠΌΠ΅ΡΡΡ, ΠΎΠΏΡΠ΅Π΄Π΅Π»ΡΠ΅ΠΌΡΠ΅ ΠΌΠ΅ΡΠΎΠ΄ΠΎΠΌ Rock-Eval (Π² ΡΠ°ΡΡΠ½ΠΎΡΡΠΈ, Π·Π½Π°ΡΠ΅Π½ΠΈΡ HI, OI ΠΈ Tpeak).An increasing rate of degradation of coastal and subsea permafrost leads to remobilization of huge amounts of organic carbon. To know how this remobilized carbon behaves while being transported through the land-shelf system is crucially important for understanding an extremely fragile Arctic ecosystem. This study is aimed at tracing the geochemical signals of organic matter along the profile from the coastal zone to the continental slope of the Laptev Sea, using the Rock-Eval approach. We investigated surface sediment samples obtained during the Arctic marine expeditions of 2018-2019 on the R/V "Akademik Mstislav Keldysh". The most active oxidation of organic matter, exported with river runoff and products of coastal erosion, occurs in the coastal zone at a depth of several tens of meters. A significant effect on the organic matter composition is exerted by the sediment export from Novosibirsk Islands eroding coastlines. We assume that various products carried by river runoff and coastal erosion are characterized by various signatures detected by the Rock-Eval method (e.g., the OI and Tpeak values). It is also shown that the mineral matrix does not seem to provide a first-order control on preventing organic matter degradation during transport from the coastal zone to deep-sea basins