Processing results from drill hole 23, Murmanskaya Area (Report 5955, Leningrad)

• Main Authors: Ronkina, Zinaida Z, Bro, Evgeny G, Sokolov, A
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 1985
• Subjects: Drilling/drill rig; VNIIO-1983; Archive of Ocean Data ARCOD; Murmansk; Kolguev; Murmanskaya; Pechora
• Online Access: https://dx.doi.org/10.1594/pangaea.690496; https://doi.pangaea.de/10.1594/PANGAEA.690496

Area of drilling: Murmanskaya Area, southern part of the South Barents Deep, Barents Sea.Reasons for drilling: 1. Obtaining additional information on the geological section in the Murmanskaya Area as well as data for stratification of the section and its allocation with reflecting seismic horizons;2. Study of properties, composition and lithologic-facial features of sedimentary rocks.Technical results:The hole has penetrated the section of 3445 m and stopped in Late Permian deposits.Scientific results:1. Comprehensive lithologic and paleontological studies (foraminifera, palynology) of drill samples from the hole have allowed to reveal lithologic features and to carry out a detailed lithologic and stratigraphic sequence of sedimentary rocks from Permian to Early Cretaceous ones. 2. Thicknesses of the units are as followed: Permian - 100 m, Early Triassic - 562 m, Middle Triassic - 460 m, Late Triassic - 438 m, Early Jurassic - 329 m, Middle Jurassic (Aalenian-Bathonian) 316 m, Late Jurassic - 125 m (Callovian - 55 m, Oxfordian?-Early Tithonian - 42 m, Middle-Late Tithonian - 28 m), Early Cretaceous - 1019 m (Berriasian - 18 m, Valanginian-Hauterivian - 66 m, Barremian-Aptian - 141 m, Aptian - 303 m, Albian - 491 m). The question about presence or absence of Late Cretaceous and Paleogene deposits (mapped in the South Barents Deep) in the section remains undetermined. Presumably these deposits have low thickness and occur above the sampling interval.3. Pre-Valanginian washout and weathering crust have been identified. Hiatuses are assumed in the post-Jurassic, post-Valanginian, and pre-Cenozoic time.4. Clayey-silty sedimentary rocks dominate in the hole. Silty-sandy rocks dominate in the Early and Middle Jurassic.5. Coals of the gas stage metamorphism occur in the Permian, Late Triassic, Middle Jurassic and Late Aptian deposits.6. Sedimentation environment has been reconstructed. Upper Permian sediments accumulated in near-shore marine and lagoonal-marine conditions. Triassic to Early Jurassic sediments accumulated in lagoonal-continental and continental conditions. Middle Jurassic to Early Cretaceous sediments accumulated in a marine basin. The marine basin was mainly shallow. Its greatest deepening was in the Late Jurassic.7. Sedimentation rate varied from 0.3 cm/kyr in the Late Jurassic to 10 cm/kyr in the Early Triassic. 8. Sedimentary rocks are lithified from ones affected by deep epigenesis to ones affected by early epigenesis.9. Mineral composition of sedimentary rocks from the Murmansk area strongly differs from one of deposits in the Kolguev Island and the Timan-Pechora region.