A combined sedimentological and organic geochemical study of the Jurassic/Cretaceous Janusfjellet formation (Svalbard), Norway

Hvoslef, Sven; Dypvik, Henning; Solli, H.

doi:10.1016/0146-6380(86)90013-6

Cited by 16 publications

(9 citation statements)

References 23 publications

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“…16B; Dypvik et al, 1991b). This interpretation is consistent with previous studies based on microfossils (Løfalidi & Thusu, 1976) and geochemistry (Dypvik, 1985;Hvoslef et al, 1986). Due to its shale-dominated character, extensive regional distribution (present in all investigated sections and wells; Fig.…”

Section: Palaeogeographic Development Of the Rurikfjellet Formationsupporting

confidence: 90%

Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data

Grundvåg¹,

Jelby²,

Śliwińska³

et al. 2019

NJG

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The Lower Cretaceous succession in Svalbard is commonly considered as an important analogue to age-equivalent strata on the Barents Shelf which are sporadically targeted by exploration wells. In this study, the stratigraphic and genetic relationship between the Rurikfjellet (open marine), Helvetiafjellet (paralic) and Carolinefjellet (open marine) formations of the Lower Cretaceous succession in Svalbard is evaluated by combining sedimentological outcrop studies with well log and core data across Nordenskiöld Land, central Spitsbergen. Sedimentological characteristics and stratigraphic units are mapped within a refined dinocyst biostratigraphic framework, enabling relatively well-constrained palaeogeographic reconstructions. The Valanginian-lowermost Barremian Rurikfjellet Formation consists of a lower shale-dominated unit of offshore origin which grades upwards into storm-reworked lower shoreface sandstones displaying hummocky cross-stratification. Local occurrences of prodeltaic successions and thick successions of gravity flow deposits containing coal-bearing slump blocks of delta plain origin in some wells, reveal a late Hauterivian progradational pulse which has previously not been recorded in Svalbard. The lower Barremianlower Aptian Helvetiafjellet Formation consists of fluvial braidplain and paralic deposits which rest unconformably on the Rurikfjellet Formation across the entire study area, reflecting regional uplift and widespread subaerial exposure prior to the onset of paralic deposition. The Helvetiafjellet Formation exhibits increased marine influence upwards, and in the investigated cores the uppermost part of the unit consists of wave-reworked mouth-bar deposits which are truncated by a transgressive conglomerate lag dominated by extrabasinal lithic clasts and intraformational siderite clasts. An up to 10 m-thick, regionally extensive, organic-rich (TOC up to 2.1 wt.%) shale unit of early Aptian age marks the base of the overlying Carolinefjellet Formation. The shale accumulated during a regional flooding event which drowned and eventually transformed the Helvetiafjellet Formation coastal plain into a shallow shelf. The organic facies of the shale unit (Type II-III kerogen) and a high Pr/Ph ratio (>2), in combination with abundant long-chained n-alkanes, suggest that the unit was deposited in a suboxic paralic marine environment strongly influenced by input of terrestrial organic matter. The investigated succession exhibits stratigraphic and petrographic resemblance to age-equivalent strata in NE Greenland, suggesting that these successions may have formed part of the same drainage system located on the northwestern margin of the Barents Shelf. Thus, by highlighting the Early Cretaceous palaeogeographic evolution in Svalbard, this study contributes to the regional stratigraphic understanding of the Lower Cretaceous succession on the wider northern Barents Shelf.

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Section: Palaeogeographic Development Of the Rurikfjellet Formationsupporting

confidence: 90%

Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data

Grundvåg¹,

Jelby²,

Śliwińska³

et al. 2019

NJG

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“…13) which suggest open-marine source rocks containing mixed Type II/III kerogen (Shanmugam, 1985). The interpreted palaeo-depositional setting corresponds to an anoxic marine shelf margin similar to that described by Hvoslef et al (1986), in which slight variations in distal/proximal locations, and proximity to palaeo-river input, control variation in the amount of Type II relative to Type III OM in the source rock.…”

Section: Inferred Source Rock Depositional Environment Data Insupporting

confidence: 54%

“…the low Pr/Ph ratio of sample SO-13) within the Group II petroleum can be explained by the variable nature of the organic matter within the Agardhfjellet Formation source rock, which ranges from Type II to Type III kerogen (Koevoets et al, 2016). This in turn indicates a range in depositional settings from restricted oxygendeficient to open marine (Hvoslef et al, 1986;Dypvik et al, 1991). Fig.…”

Section: Oil -Source Correlationmentioning

confidence: 96%

Migrated Petroleum in Outcropping Mesozoic Sedimentary Rocks in Spitsbergen: Organic Geochemical Characterization and Implications for Regional Exploration

Abay

Karlsen

Lerch

et al. 2016

Journal of Petroleum Geology

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The presence of migrated petroleum in outcropping rocks on Spitsbergen (Svalbard archipelago) has been known for several decades but the petroleum has not been evaluated by modern geochemical methods. This paper presents detailed organic geochemical observations on bitumen in outcrop samples from central and eastern Spitsbergen. The samples comprise sandstones from the Lower Cretaceous Carolinefjellet Formation, the Upper Triassic – Middle Jurassic Wilhelmøya Subgroup and the Upper Triassic De Geerdalen Formation; a limestone from the De Geerdalen Formation; and carbonates from the Middle Jurassic – Lower Cretaceous Agardhfjellet Formation. In addition a palaeo‐seepage oil was sampled from a vug in the Middle Triassic Botneheia Formation. This data is integrated with the results of analyses of C1–C4 hydrocarbon fluid inclusions trapped in quartz and calcite cements in these samples. Organic geochemical data suggest that the petroleum present in the samples analysed can be divided into two compositional groups (Group I and Group II). Group I petroleums have distinctive biomarker characteristics including Pr/Ph ratios of about 1.3–1.5, high tricyclic terpanes relative to pentacyclic terpanes, and relatively high methyl‐dibenzothiophenes compared to methyl‐phenanthrenes. By contrast Group II petroleums have low tricyclic terpanes relative to pentacyclic terpanes and low methyl‐dibenzothiophenes compared to methyl‐phenanthrenes, and most Pr/Ph ratios range from 1.90 to 2.57. The petroleum in both groups was derived from marine shale source rocks deposited in proximal to open marine settings. Group I petroleums, present in the sandstones of the Wilhelmøya Subgroup and the De Geerdalen Formation and as a palaeo‐seepage oil in the vug in the Botneheia Formation, are likely to have been sourced from the Middle Triassic Botneheia Formation. Group II petroleums, found in the sandstone of the Carolinefjellet Formation, the limestone from the De Geerdalen Formation and in carbonates of the Agardhfjellet Formation, are inferred to have been generated from the Jurassic‐Cretaceous Agardhfjellet Formation. The analysis of biomarker and aromatic hydrocarbons in the petroleums indicate three relative maturation levels, equivalent to expulsion at vitrinite reflectances of about 0.7–0.8%Rc, 0.8–0.9%Rc and 1.0–1.6%Rc. On average, Triassic host rocks contain petroleum of higher maturity compared to the Jurassic and Cretaceous host rocks. The fluid inclusion data suggest that gaseous hydrocarbons from the sandstones of the Wilhelmøya Subgroup are thermogenic, and are of similar maturity to the petroleum in extracts from these sandstones, suggesting that the gas was generated together with oil in the oil window. By contrast the inclusion gases from carbonate rocks analysed have a mixed (thermogenic / biogenic) origin. The outcropping rocks in which these oils occur are analogous to offshore reservoirs on the Norwegian Continental Shelf. The study may therefore improve our understanding of the subsurface offshore petroleum systems in the...

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“…Interpretation: Hvoslef et al (1986), Koevoets et al (2016) and Abay et al (2017) showed that the paper shale in the Agardhfjellet Formation (F1) has a high HI index (236 mg HC/g organic C) and TOC values of up to 12.8%. This, together with the absent or sparse trace fossils and benthic invertebrate fossils, suggests anoxic sea-floor conditions.…”

Section: Facies and Facies Associationsmentioning

confidence: 99%

Integrating subsurface and outcrop data of the Middle Jurassic to Lower Cretaceous Agardhfjellet Formation in central Spitsbergen

Koevoets¹,

Hammer²,

Olaussen³

et al. 2018

NJG

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The Longyearbyen CO 2 storage project drilling and coring campaign in central Spitsbergen provided new insights on the shale-dominated Middle Jurassic to Lower Cretaceous Agardhfjellet Formation, which is the onshore counterpart to the Fuglen Formation and the prolific source rocks of the Hekkingen Formation in the Barents Sea. Logs of magnetic susceptibility, organic carbon content, organic carbon isotopes and XRF geochemistry on the cores, together with wireline logs, biostratigraphy and sedimentology, have made it possible to refine the interpretation of the depositional environment and to identify transgressive-regressive (TR) sequences. Several key sequence-stratigraphic surfaces are identified and suggested to be correlative in Central Svalbard, and four of them, although not necessarily chronostratigraphic, also to surfaces in the Barents Sea. Due to the nearly flat-lying thrust faults in the upper décollement zone of the West Spitsbergen Fold and Thrust Belt, there is some concern about the lateral correlation of the sequences within Spitsbergen. However, some of the TR sequence surfaces appear to be of regional importance and are recognised both onshore Svalbard and offshore on the Barents Shelf. The observations suggest a shallow-marine shelf depositional environment within an epicontinental sea with variable dysoxic, anoxic and oxic sea-floor conditions. The majority of the facies vary from outer shelf to transition zone or prodelta and lower shoreface/distal delta front. In one outcrop, proximal facies, i.e., delta front or middle shoreface, are recognised. In our study area the nearly 250 m-thick, fine-grained Agardhfjellet Formation is proposed to represent distal shoreline clinoforms and a precursor to the overlying forward-and southward-stepping wedge of the Valanginian Rurikfjellet Formation and the Barremian to Early Aptian Helvetiafjellet Formation.

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A combined sedimentological and organic geochemical study of the Jurassic/Cretaceous Janusfjellet formation (Svalbard), Norway

Cited by 16 publications

References 23 publications

Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data

Sedimentology and palynology of the Lower Cretaceous succession of central Spitsbergen: integration of subsurface and outcrop data

Migrated Petroleum in Outcropping Mesozoic Sedimentary Rocks in Spitsbergen: Organic Geochemical Characterization and Implications for Regional Exploration

Integrating subsurface and outcrop data of the Middle Jurassic to Lower Cretaceous Agardhfjellet Formation in central Spitsbergen

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