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Litologi, sedimentologi och kolisotopstratigrafi över krita–paleogen-gränsintervallet i borrningen Limhamn-2018

Molin, Emmy LU (2019) In Examensarbeten i geologi vid Lunds universitet GEOL01 20191
Department of Geology
Abstract (Swedish)
Krita-paleogen-gränsen har länge varit central i diskussioner mellan forskare runt om i världen, då den markerar/sammanfaller med utdöendet av 75% av jordens arter till följd av ett enormt asteriodnedslag på Chicxulúbhalvön i Mexiko. Gränsintervallet är vida utbrett i sedimentära lagerföljder som bildades under denna tid, och kan identifieras genom sina unika kemiska egenskaper och karakteristiska litologier skapad av material från nedslaget som spreds kring jorden. Genom att jämföra gränsintervallet vid referenslokalen Stevns Klint i Danmark med samma intervall i Limhamns kalkbrott, beläget i södra Sverige, har tidigare studier konkluderat att det karakteristiska så kallade Fiskelerledet, som representerar gränsintervallet i Stevns Klint,... (More)
Krita-paleogen-gränsen har länge varit central i diskussioner mellan forskare runt om i världen, då den markerar/sammanfaller med utdöendet av 75% av jordens arter till följd av ett enormt asteriodnedslag på Chicxulúbhalvön i Mexiko. Gränsintervallet är vida utbrett i sedimentära lagerföljder som bildades under denna tid, och kan identifieras genom sina unika kemiska egenskaper och karakteristiska litologier skapad av material från nedslaget som spreds kring jorden. Genom att jämföra gränsintervallet vid referenslokalen Stevns Klint i Danmark med samma intervall i Limhamns kalkbrott, beläget i södra Sverige, har tidigare studier konkluderat att det karakteristiska så kallade Fiskelerledet, som representerar gränsintervallet i Stevns Klint, inte återfinns i Limhamn. Avsaknaden av Fiskelerledet beror antingen på lokala variationer i sedimentationsmiljö, alternativt är ersatt av en hiatus med okänd omfattning. I denna studie, har detaljerade undersökningar av litologi och fossilinnehåll samt isotopstudier av δ13Ccarb- data utförts över gränsintervallet i borrkärnan Limhamn-2018 vilka jämförs med tidigare studier vid Stevns Klint. Litologin (baserad på Dunhamns klassifikationssystem) i Limhamn-2018 består till stora delar av mudstone i kritasekvensen och wackestone i paleogensekvensen med genomgående noduler av hårt litifierad kalksten innehållande flintakonkretioner. Detta, tillsammans med en litteraturstudie kring lokalerna, visar på att bergartssekvensen, liksom den i Stevns Klint, består av bryozodominerade kallvattenkarbonater avsatta i en marin bassäng med varierande vattendjup genom sen krita och tidig paleogen. Att bestämma omfattningen av hiatusen i Limhamn-2018 har visat sig svårt utan ingående biostratigrafiska undersökningar, men genom att använda δ13Ccarb data för att lokalisera gränsintervallet i borrkärnan, samt jämföra dessa med publicerad isotopdata från Stevns Klint, kan slutsatsen dras att hiatusen förmodligen inte är speciellt omfattande. Således kommer den nya borrningen Limhamn-2018 sannolikt att vara betydelsefull för framtida studier av K-Pg-gränsen, det associerade utdöendet samt det rådande klimatet under avsättningstiden i den svenska delen av Danska bassängen. (Less)
Abstract
The Cretaceous-Paleogene boundary has long been a center of discussion amongst scientists as it marks the extinction of 75% of all species on Earth. This mass extinction event was probably caused by an enormous asteroid impact event in what is now Mexico. The boundary interval is easily identified in the sedimentary geological record because of its unique chemical properties as well as its characteristic lithologies containing ejecta material from the impact that was spread across the globe. By comparing the stratigraphic record across the event at Stevns Klint in Denmark with coeval strata in the Limhamn Quarry of southern Sweden, previous studies have concluded that these seem to be quite different from one another. Particularly this... (More)
The Cretaceous-Paleogene boundary has long been a center of discussion amongst scientists as it marks the extinction of 75% of all species on Earth. This mass extinction event was probably caused by an enormous asteroid impact event in what is now Mexico. The boundary interval is easily identified in the sedimentary geological record because of its unique chemical properties as well as its characteristic lithologies containing ejecta material from the impact that was spread across the globe. By comparing the stratigraphic record across the event at Stevns Klint in Denmark with coeval strata in the Limhamn Quarry of southern Sweden, previous studies have concluded that these seem to be quite different from one another. Particularly this pertains to the characteristic Fiskeler Member found the basalmost Paleogene in Stevns Klint and which is seemingly missing in Limhamn, either due to a hiatus or local differences between the localities. In this study, studies of lithological and paleontological properties, as well as δ13Ccarb have been performed across the K-Pg boundary interval in the new drill core Limhamn-2018, and the results of which are compared to previous studies from Stevns Klint. The lithology (based on the Dunhamn classification) in Limhamn-2018 consists of primarily mudstone in the Cretaceous and wackestone in the Paleogene, with frequent nodules of hard lithified limestone containing concretions of flint. This alongside a literature study of the localities shows that the sequence in Limhamn consists, much like that at Stevns Klint, of bryozoan-dominated, cool-water carbonates deposited in a basin with variable water depths throughout the late Cretaceous and early Paleogene. Determining the precise extent of the boundary hiatus in Limhamn-2018 has been proven difficult without detailed biostratigraphic investigation. However, combining the lithological and isotopic changes allowed the boundary to be pinpointed in the drill core and comparisons to the δ13Ccarb patterns from Stevns Klint suggest that the hiatus might not be extensive. Limhamn-2018 will serve as an important new section for upcoming studies of the K-Pg boundary interval, the associated extinction event, and the environmental setting of the Swedish part of the Danish basin. (Less)
Please use this url to cite or link to this publication:
author
Molin, Emmy LU
supervisor
organization
alternative title
Lithology, sedimentology and carbon isotope stratigraphy over the Cretaceous–Paleogene boundary interval in the drill core Limhamn-2018
course
GEOL01 20191
year
type
M2 - Bachelor Degree
subject
keywords
Limhamn, K—Pg-gränsen, Stevns Klint, De baltoskandiska kallvattenkarbonaterna, Litologi, Kolisotopstratigrafi, C—Pg boundary, The baltoscandian cool water carbonates, Lithology, Carbon isotope stratigraphy
publication/series
Examensarbeten i geologi vid Lunds universitet
report number
566
language
Swedish
id
8983932
date added to LUP
2019-06-14 16:43:20
date last changed
2019-06-14 16:43:20
@misc{8983932,
  abstract     = {The Cretaceous-Paleogene boundary has long been a center of discussion amongst scientists as it marks the extinction of 75% of all species on Earth. This mass extinction event was probably caused by an enormous asteroid impact event in what is now Mexico. The boundary interval is easily identified in the sedimentary geological record because of its unique chemical properties as well as its characteristic lithologies containing ejecta material from the impact that was spread across the globe. By comparing the stratigraphic record across the event at Stevns Klint in Denmark with coeval strata in the Limhamn Quarry of southern Sweden, previous studies have concluded that these seem to be quite different from one another. Particularly this pertains to the characteristic Fiskeler Member found the basalmost Paleogene in Stevns Klint and which is seemingly missing in Limhamn, either due to a hiatus or local differences between the localities. In this study, studies of lithological and paleontological properties, as well as δ13Ccarb have been performed across the K-Pg boundary interval in the new drill core Limhamn-2018, and the results of which are compared to previous studies from Stevns Klint. The lithology (based on the Dunhamn classification) in Limhamn-2018 consists of primarily mudstone in the Cretaceous and wackestone in the Paleogene, with frequent nodules of hard lithified limestone containing concretions of flint. This alongside a literature study of the localities shows that the sequence in Limhamn consists, much like that at Stevns Klint, of bryozoan-dominated, cool-water carbonates deposited in a basin with variable water depths throughout the late Cretaceous and early Paleogene. Determining the precise extent of the boundary hiatus in Limhamn-2018 has been proven difficult without detailed biostratigraphic investigation. However, combining the lithological and isotopic changes allowed the boundary to be pinpointed in the drill core and comparisons to the δ13Ccarb patterns from Stevns Klint suggest that the hiatus might not be extensive. Limhamn-2018 will serve as an important new section for upcoming studies of the K-Pg boundary interval, the associated extinction event, and the environmental setting of the Swedish part of the Danish basin.},
  author       = {Molin, Emmy},
  keyword      = {Limhamn,K—Pg-gränsen,Stevns Klint,De baltoskandiska kallvattenkarbonaterna,Litologi,Kolisotopstratigrafi,C—Pg boundary,The baltoscandian cool water carbonates,Lithology,Carbon isotope stratigraphy},
  language     = {swe},
  note         = {Student Paper},
  series       = {Examensarbeten i geologi vid Lunds universitet},
  title        = {Litologi, sedimentologi och kolisotopstratigrafi över krita–paleogen-gränsintervallet i borrningen Limhamn-2018},
  year         = {2019},
}