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Stratigraphy and palaeoenvironment of the early Jurassic volcaniclastic strata at Djupadalsmölla, central Skåne, Sweden

Wahlquist, Per LU (2023) In Dissertations in Geology at Lund University GEOR02 20211
Department of Geology
Abstract
From the almost 200 volcanic outcrops in the Central Skåne Volcanic Province (CSVP), only three are of volcaniclastic material. These volcanoclastics, and the transition to the underlying crystalline basement, have been investigated for the first time in a drill core (KBH2) from Djupadalsmölla in order to understand the stra-tigraphy, depositional process, age of deposition, and depositional environment. The core constitutes three rock units, in ascending order: the kaolinite weathered crystalline basement, a thin dark coloured mudstone, and a mas-sive lapilli tuff (volcaniclastics). From the degraded state of the crystalline basement, it is clear that extensive che-mical weathering tock place implying a wet and humid climate. Through... (More)
From the almost 200 volcanic outcrops in the Central Skåne Volcanic Province (CSVP), only three are of volcaniclastic material. These volcanoclastics, and the transition to the underlying crystalline basement, have been investigated for the first time in a drill core (KBH2) from Djupadalsmölla in order to understand the stra-tigraphy, depositional process, age of deposition, and depositional environment. The core constitutes three rock units, in ascending order: the kaolinite weathered crystalline basement, a thin dark coloured mudstone, and a mas-sive lapilli tuff (volcaniclastics). From the degraded state of the crystalline basement, it is clear that extensive che-mical weathering tock place implying a wet and humid climate. Through palynological studies of the mudstone unit the depositional environment was likely a restricted bay or lagoon with limited marine influences surrounded by a forest covered wetland at the time of volcanism. The age of the mudstone could be determined to late Pliensbachian through the palynomorphs. Petrographic analysis shows that all but the lowermost part of the volcaniclastic deposit has a lapilli tuff texture. The material is, however, highly degraded and replaced by swelling clay minerals and highly affected by diagenetic processes. The depositional process could only be narrowed down to two alternatives. Either directly deposited by a pyroclastic flow or secondarily deposited by a lahar. (Less)
Popular Abstract (Swedish)
Av de nästan 200 blottningarna av vulkaniska bergarter som kan ses i Central Skåne Volcanic Province (CSVP) består endast tre av vulkanoklastiskt material. Stratigrafin i dessa avlagringar vars förhållande till underliggande urberg har för första gången beskrivits i en borrkärna (KBH2) från Djupadalsmölla för att bestämma stratigrafin samt avsättningsprocessen, åldern och avsättningsmiljön. Borrkärnan består av tre enheter i stigande ordning: det kaolinitvitrade kristallina urberget, den mörka lerstenen, och den massiva lapilli tuffen (vulkanoklastisk). Utifrån urbergets vittrade tillstånd står det klart att utbredd kemisk vittring ägde rum vilket tyder på ett mycket blött och fuktigt klimat. Palynologiska studier av lerstenen tyder på att... (More)
Av de nästan 200 blottningarna av vulkaniska bergarter som kan ses i Central Skåne Volcanic Province (CSVP) består endast tre av vulkanoklastiskt material. Stratigrafin i dessa avlagringar vars förhållande till underliggande urberg har för första gången beskrivits i en borrkärna (KBH2) från Djupadalsmölla för att bestämma stratigrafin samt avsättningsprocessen, åldern och avsättningsmiljön. Borrkärnan består av tre enheter i stigande ordning: det kaolinitvitrade kristallina urberget, den mörka lerstenen, och den massiva lapilli tuffen (vulkanoklastisk). Utifrån urbergets vittrade tillstånd står det klart att utbredd kemisk vittring ägde rum vilket tyder på ett mycket blött och fuktigt klimat. Palynologiska studier av lerstenen tyder på att avsättningsmiljön var en av-gränsad marin vik eller lagun i ett annars skogsklätt landskap när vulkanismen ägde rum. Åldern på lerstenen kunde också bestämmas till sen Pliensbachian utifrån de palynologiska studierna. Petrografisk analys visade att allt utom den allra nedersta delen av det vulkanoklastiska materialet påvisas ha en lapilli tuff textur, dock är det klart att materialet är mycket nedbrutet och ersatt av svällande lermineral men även starkt påverkade av diagenetiska pro-cesser. Den exakta avsättningsprocessen kunde inte identifieras men två alternativ kunde nås. Antigen direktavsatt från ett pyroklastiskt flöde eller en sekundärt avsatt av en lahar. (Less)
Please use this url to cite or link to this publication:
author
Wahlquist, Per LU
supervisor
organization
alternative title
Stratigrafi och paleomiljö av tidig jurassisk vulkanoklastisk strata vid Djupadalsmölla i centrala Skåne
course
GEOR02 20211
year
type
H2 - Master's Degree (Two Years)
subject
keywords
volcaniclastic, Djupadalsmölla, CSVP, palynomorphs, early Jurassic, late Pliensbachian
publication/series
Dissertations in Geology at Lund University
report number
646
language
English
id
9109507
date added to LUP
2023-01-31 12:42:23
date last changed
2023-01-31 12:42:23
@misc{9109507,
  abstract     = {{From the almost 200 volcanic outcrops in the Central Skåne Volcanic Province (CSVP), only three are of volcaniclastic material. These volcanoclastics, and the transition to the underlying crystalline basement, have been investigated for the first time in a drill core (KBH2) from Djupadalsmölla in order to understand the stra-tigraphy, depositional process, age of deposition, and depositional environment. The core constitutes three rock units, in ascending order: the kaolinite weathered crystalline basement, a thin dark coloured mudstone, and a mas-sive lapilli tuff (volcaniclastics). From the degraded state of the crystalline basement, it is clear that extensive che-mical weathering tock place implying a wet and humid climate. Through palynological studies of the mudstone unit the depositional environment was likely a restricted bay or lagoon with limited marine influences surrounded by a forest covered wetland at the time of volcanism. The age of the mudstone could be determined to late Pliensbachian through the palynomorphs. Petrographic analysis shows that all but the lowermost part of the volcaniclastic deposit has a lapilli tuff texture. The material is, however, highly degraded and replaced by swelling clay minerals and highly affected by diagenetic processes. The depositional process could only be narrowed down to two alternatives. Either directly deposited by a pyroclastic flow or secondarily deposited by a lahar.}},
  author       = {{Wahlquist, Per}},
  language     = {{eng}},
  note         = {{Student Paper}},
  series       = {{Dissertations in Geology at Lund University}},
  title        = {{Stratigraphy and palaeoenvironment of the early Jurassic volcaniclastic strata at Djupadalsmölla, central Skåne, Sweden}},
  year         = {{2023}},
}