Processing results from drill hole VNIIO-1983-25 in the Murmanskaya Area, southern part of the South Barents Deep (Report 6383, Leningrad)

• Main Authors: Ronkina, Zinaida Z, Bro, Evgeny G
• Format: Article in Journal/Newspaper
• Language: English
• Published: PANGAEA - Data Publisher for Earth & Environmental Science 1989
• Subjects: Drilling/drill rig; VNIIO-1983; Archive of Ocean Data ARCOD; Murmansk; Kolguev; Murmanskaya; Pechora
• Online Access: https://dx.doi.org/10.1594/pangaea.690547; https://doi.pangaea.de/10.1594/PANGAEA.690547

Area of drilling: Murmanskaya Area, southern part of the South Barents Deep, Barents Sea.Reasons for drilling: 1. Study of the geological section in the Murmanskaya area.2. Obtaining data for stratification of the section and its allocation with reflecting seismic horizons;3. Study of properties, composition and lithologic-facial features of sedimentary rocks.Technical results:The hole has penetrated the section of 2591 m and stopped in the Late Triassic 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 Mesozoic and Cenozoic sedimentary rocks from Late Triassic to Early Cretaceous ones. 2. Thicknesses of the units are as followed: Late Triassic - 608 m, Early Jurassic - 304 m, Middle Jurassic (Aalenian-Bathonian) 319 m, Late Jurassic - 114 m (Callovian-Kimmeridgian - 96 m, Tithonian - 18 m), Early Cretaceous - 1246 m (Berriasian-Hauterivian - 77 m, Barremian-Aptian - 470 m, Albian - 699 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. Sedimentation rate varied from 0.3 cm/kyr in the Late Jurassic to 10 cm/kyr in the Early Triassic.4. Pre-Valanginian washout and weathering crust as well as pre-Cenozoic washout have been identified. Hiatuses are assumed in the post-Jurassic, post-Valanginian, and pre-Cenozoic time.5. Generally clayey-silty sedimentary rocks dominate in the hole. Silty-sandy rocks dominate in the Triassic, Early and Middle Jurassic.6. Coals of gas stage metamorphism occur in the Late Triassic, Middle Jurassic and Late Aptian deposits.7. Sedimentation environment has been reconstructed. Triassic sediments accumulated in Lagoonal-continental and lagoonal-marine conditions. Triassic to Jurassic sediments accumulated in lagoonal-continental and continental conditions. Middle Jurassic to Early Cretaceous sediments accumulated in a marine mainly shallow basin, which deepened in the Late Jurassic.8. Maximal downwarping was in the Triassic and in the end of the Early Cretaceous.9. Sedimentary rocks are lithified from ones affected by deep epigenesis (Triassic) to ones affected by early epigenesis (Early Jurassic to Early Cretaceous).10. Mineral composition of sedimentary rocks from the Murmansk area strongly differs from one of deposits in the Kolguev Island and the Timan-Pechora region.11. During the Late Jurassic black clays enriched in organic matter accumulated. This resulted from scarcity of sedimentary material, very low sedimentation rates, and a rather deep basin of sedimentation.