ALBERT

Description: Project 74-4/683 - Proceeding and Generalization of Materials of Parametric Drilling on Arctic Islands (Nagurskaya and Severnaya parametric drill holes on the Franz Josef Land Archipelago). Reasons for drilling: 1. Study of the geological-geophysical section from the eastern part of the Franz Josef Land Archipelago for establishing structure of the sedimentary cover, rock properties and composition. 2. Obtaining information for stratification of the section and its allocation with geophysical sections. Technical results: The hole was drilled from 14.12.1977 till 03.01.1979. It has penetrated the section of 3523 m and stopped in Early?-Middle Triassic deposits. Scientific results: 1. Stratigraphic sequence (based on different faunal groups, leaf flora, sporen, pollen) of the section has been carried out. 2. Middle-Late Triassic deposits lay almost horizontally. Middle Triassic deposits are composed of dark-colored terrigenous rocks of marine origin. They are divided to two series. The lower series 1025 m thick is composed of alternating patterns of sandstones, siltstones, and argillites with predomination of silty-clayey rocks. The upper series 430 m thick is composed of argillites with small admixture of silty material. 3. Upper Triassic deposits are composed of (from down to up): marine sandy-silty Carnian rocks (470 m), a series of rhythmically alternating obliquely laminated sandstones and siltstones with tributary layers of argillites, coaly rocks, hard coal lenses (990 m), dark marine silty clays (160 m), a series of obliquely laminated sands and sandstones with pyrite and siderite concretions (450 m). 4. The hole has crossed 6 sills from 5 to 87 m thick. The sills occur with interval 400-600 m and comprise ~6% of thickness of the sedimentary complex. Thinner sills (5-7 m) are composed of glassy dolerites and microdolerites, the thickest sills are composed of micropegmatite gabbro and olivine gabbro-dolerites. The sills intruded from the end of the Early Cretaceous till the Early Paleocene. 5. During the Middle Triassic and Carnian sedimentation was within a marine basin with highly reduced conditions. During most of the Norian sediment formation was within a vast littoral lake-alluvial plain that periodically submerged and flooded by sea.