Triassic–Jurassic weathering and clay mineral dispersal in basement areas and sedimentary basins of southern Sweden

Ahlberg, Anders; Olsson, Ingela; Šimkevičius, Petras

doi:10.1016/s0037-0738(02)00381-0

Cited by 64 publications

(30 citation statements)

References 23 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Evidence of deep weathering during the Jurassic/Early Cretaceous has been identified in southern Sweden (e.g., Lidmar-Bergström 1982Migón & Lidmar-Bergström, 2001;Ahlberg et al, 2003). Possible time-equivalent remnants in southern Norway have been suggested by Olesen et al (2006) and Riis (1996), and these might extend westward into the North Sea region (Roaldset et al, 1993).…”

Section: Pre-upper Jurassicmentioning

confidence: 97%

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Riber¹,

Dypvik²,

Sørlie³

2015

NJG

View full text Add to dashboard Cite

As part of the recent discoveries on the Utsira High (Edvard Grieg and Johan Sverdrup fields), altered and fractured basement rocks were for the first time shown to act as a reservoir and possible migration paths for commercial hydrocarbon deposits on the Norwegian Continental Shelf. Altered basement rocks are underlying the main Upper Jurassic reservoir rocks in Johan Sverdrup and the main Cretaceous, Jurassic and Triassic reservoir rocks in Edvard Grieg. In the present study, eighteen basement cores from the Utsira High have been classified and investigated for signs of alteration, including subaerial weathering. The results show highly variable basement composition, including metasandstones, phyllites, granites, granodiorites and gabbroic rocks. In core view most of the basement rocks show signs of a medium to high degree of fracturing. Alteration has taken place in most of the cores, ranging from slight discoloration to disintegration along fractures, and to total fragmentation of the rock. The fragmentation of the rock is commonly associated with the dissolution of primary minerals and precipitation of secondary clays in the newly formed pore space. The upwards increasing disintegration and increasing amount of clay observed in the basement rocks from two of the wells (16/3-4 and 16/1-15) indicate that subaerial weathering was the main alteration agent.

show abstract

Section: Pre-upper Jurassicmentioning

confidence: 97%

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Riber¹,

Dypvik²,

Sørlie³

2015

NJG

View full text Add to dashboard Cite

show abstract

“…Clay mineral analyses document high amounts of kaolinite in the Triletes Beds (Supplementary Figs S2,S3), which is typical of strongly leached soils that become progressively enriched in aluminium. Based on sedimentological and clay mineralogical analyses of Rhaetian palaeosols, it was concluded that the latest Triassic witnessed extremely humid climate conditions across northern Europe 31 . Whereas we do not discount the role of climate changes in the T/J boundary proliferation of pteridophytes, we deem it improbable that a mere increase in precipitation due to greenhouse warming could have triggered rampant growth of only a few fern species over such a vast area.…”

Section: Floral Changes Across the Triassic/jurassic Boundarymentioning

confidence: 99%

Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism

et al. 2009

View full text Add to dashboard Cite

One of the five largest mass extinctions of the past 600 million years occurred at the boundary of the Triassic and Jurassic periods, 201.6 million years ago. The loss of marine biodiversity at the time has been linked to extreme greenhouse warming, triggered by the release of carbon dioxide from flood basalt volcanism in the central Atlantic Ocean. In contrast, the biotic turnover in terrestrial ecosystems is not well understood, and cannot be readily reconciled with the effects of massive volcanism. Here we present pollen, spore and geochemical analyses across the Triassic/Jurassic boundary from three drill cores from Germany and Sweden. We show that gymnosperm forests in northwest Europe were transiently replaced by fern and fern-associated vegetation, a pioneer assemblage commonly found in disturbed ecosystems. The Triassic/Jurassic boundary is also marked by an enrichment of polycyclic aromatic hydrocarbons, which, in the absence of charcoal peaks, we interpret as an indication of incomplete combustion of organic matter by ascending flood basalt lava. We conclude that the terrestrial vegetation shift is so severe and wide ranging that it is unlikely to have been triggered by greenhouse warming alone. Instead, we suggest that the release of pollutants such as sulphur dioxide and toxic compounds such as the polycyclic aromatic hydrocarbons may have contributed to the extinction.

show abstract

“…The onset of regional maritime humidity in the Rhaetian led to deep basement weathering and the development of extensive peat-forming mires in fluvio-deltaic and marginal marine settings. The thick accumulations of Rhaetian siliciclastic strata are rich in plant and animal body and trace fossils (Ahlberg et al 2002(Ahlberg et al , 2003b.…”

Section: Geological Setting and Stratigraphymentioning

confidence: 99%

“…Hermelin 1773; Troedsson 1943Troedsson , 1951Sivhed 1984;Pieńkowski 1991a The basal Vallåkra Member consists mainly of mudstones and siltstones, reaching a maximum thickness of 30 m. The overlying heterolithic Bjuv Member incorporates coal seams, palaeosols and crevasse splay sands representing mostly lowenergy floodplain deposits. The two major coals are regionally important markers and are designated the B (lower) and A (upper) seams: the upper surface of the latter has been proposed to mark the Tr -J boundary (Sivhed 1984;Ahlberg et al 2003b). The uppermost member, the Helsingborg Member, forms the bulk of the Höganäs Formation and constitutes basal Jurassic heterolites, arenites and mudstones with thin coal seams (Ahlberg et al 2003a).…”

Section: Geological Setting and Stratigraphymentioning

confidence: 99%

Palynostratigraphy of dinosaur footprint-bearing deposits from the Triassic–Jurassic boundary interval of Sweden

Vajda

Calner

Ahlberg

2013

GFF

Self Cite

View full text Add to dashboard Cite

Triassic–Jurassic weathering and clay mineral dispersal in basement areas and sedimentary basins of southern Sweden

Cited by 64 publications

References 23 publications

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Altered basement rocks on the Utsira High and its surroundings, Norwegian North Sea

Floral changes across the Triassic/Jurassic boundary linked to flood basalt volcanism

Palynostratigraphy of dinosaur footprint-bearing deposits from the Triassic–Jurassic boundary interval of Sweden

Contact Info

Product

Resources

About