Early land plant spores from the Paleozoic of Sweden – taxonomy, stratigraphy and paleoenvironments
(2013) In Litholund theses- Abstract
- The Silurian through earliest Devonian, between ca 444 and 412 million years ago, was characterized by significant changes in global climate and environment. At that time, plants and animals had begun to expand the colonization of previous relatively desolate terrestrial landscape. Macrofossils of land plants are very rare from this period because these early land plants lacked large and robust tissues that could be easily fossilized. The spores produced by these early land plants are, therefore, an important tool for resolving the establishment of the early vegetation on Earth. Spore walls are composed of sporopollenin, a complex mix of biopolymers incorporating long chains of fatty acids, phenolics, phenylpropanoids and traces of... (More)
- The Silurian through earliest Devonian, between ca 444 and 412 million years ago, was characterized by significant changes in global climate and environment. At that time, plants and animals had begun to expand the colonization of previous relatively desolate terrestrial landscape. Macrofossils of land plants are very rare from this period because these early land plants lacked large and robust tissues that could be easily fossilized. The spores produced by these early land plants are, therefore, an important tool for resolving the establishment of the early vegetation on Earth. Spore walls are composed of sporopollenin, a complex mix of biopolymers incorporating long chains of fatty acids, phenolics, phenylpropanoids and traces of carotenoids that are, collectively, very resistant to desiccation, pressure and high temperatures. These properties make spores easily preserved as fossils in the sedimentary deposits. Fossil spores can be used as a tool to: study diversity of the terrestrial vegetation, date and correlate sedimentary successions (biostratigraphy), make paleoenvironmental and paleoclimatic interpretations and, finally, assess the potential for hydrocarbon (gas, oil and coal) generation in the sediments.
During the Silurian, the paleocontinent Baltica, of which Sweden was a part, was covered by shallow seas. However, the study area in central and southern Skåne was not too distant from the coast. The sediments here were deposited in foreshore to shoreface environments with water depths no more than a few tens of meters, and in some areas, represented by Lower Devonian successions, possibly even in non-marine environments such as rivers and lakes. Spores from the early land plants were transported by river water into the shallow sea and sank to the bottom as they lost buoyancy. Today these spores from early land plants are preserved in the mid-Paleozoic sedimentary rocks exposed in present day Skåne and on Gotland.
In this project, sedimentary rock samples obtained from drill cores and outcrop at several localities in Skåne and Gotland, were processed by acid dissolution techniques to recover assemblages of organic-walled palynomorphs – mainly plant spores, detrital organic material, and marine palynomorphs. These palynological assemblages were studied by light microscopy to determine the diversity of spore taxa through several short stratigraphic intervals at various sites. Many of the bore cores were drilled by the Swedish Geological Survey during the 1960s and have never been investigated for their fossil spore content. Overall, there have been very few studies of spores from the Silurian of the Baltic region and the knowledge about the composition of the early land floras from this part of the world is sparse.
In this thesis, rich and well-preserved assemblages of early land plant spores are described from both drill core and outcrop samples from Skåne. Both cryptospores (produced by the earliest land plants) and trilete spores (produced by vascular plants) have been recovered. In total, 66 species of both cryptospores and trilete spores were identified in the upper Silurian and Lower Devonian successions of Skåne. These results reveal a rather diverse early terrestrial flora previously unrecognized in the region. Further, a revised stratigraphy for the Öved Sandstone Formation is presented as the c. upper 100 metres of the succession is based on palynostratigraphy of this study shown to represent Devonian strata.
From the Burgsvik Formation, on Gotland, sediments coeval to the studied sections in Skåne, also yielded spores from early land plants. In these beds, the earliest land plant fossil with in situ cryptospores from Baltica was discovered. These remains consist of spore masses with part of the sporangium still preserved, a possible land plant axis, and also more poorly preserved spore masses interpreted to be coprolites (fossil feaces) from arthropods. This last category represents one of the earliest examples of plant-animal interactions globally.
Further, this study reports the oldest evidence of land plants in Sweden. This is in the form of spores identified in Upper Ordovician sedimentary successions in drill core material from Röstånga, Skåne. (Less) - Abstract (Swedish)
- Popular Abstract in Swedish
Denna studie omfattar tidsperioderna ordovicium, silur och äldsta devon. Silurperioden sträcker sig från 444 till 416 miljoner år sedan och karakteriseras av globala miljö- och klimatförändringar. Vid denna tid hade djur och växter börjat kolonisera land, land som tidigare varit ödsligt och kargt. Min studie visar att det i Skåne då redan fanns en flora bestående av primitiva landväxter. Dock är fossil som är stora nog att se med blotta ögat, så kallade makrofossil, av landväxter mycket ovanliga från denna period. Detta beror antagligen på att de tidiga växterna förmodligen saknade vedämnen som lättare fossiliseras. Sporer innesluter själva cellen med DNA och kromosomer, och ytterhöljet är till... (More) - Popular Abstract in Swedish
Denna studie omfattar tidsperioderna ordovicium, silur och äldsta devon. Silurperioden sträcker sig från 444 till 416 miljoner år sedan och karakteriseras av globala miljö- och klimatförändringar. Vid denna tid hade djur och växter börjat kolonisera land, land som tidigare varit ödsligt och kargt. Min studie visar att det i Skåne då redan fanns en flora bestående av primitiva landväxter. Dock är fossil som är stora nog att se med blotta ögat, så kallade makrofossil, av landväxter mycket ovanliga från denna period. Detta beror antagligen på att de tidiga växterna förmodligen saknade vedämnen som lättare fossiliseras. Sporer innesluter själva cellen med DNA och kromosomer, och ytterhöljet är till för att skydda innehållet från till exempel uttorkning och UV-strålning. Höljet består av sporopollenin som är mycket motståndskraftigt mot nedbrytning och sporerna bevaras därför ofta som fossil i lagerföljderna.. Därför är de mikroskopiska sporer, som dessa primitiva växter framställde för sin förökning i många avseenden viktiga verktyg inom forskningen om tidiga växter. De kan användas för att studera diversitet (artrikedom) i den tidiga landfloran, man kan åldersbestämma lagerföljder med hjälp av sporer, (biostratigrafi) och man kan använda sporerna för miljö- och klimattolkning. Dessutom har sporerna den egenskapen att de ändrar färg vid tryck och temperatur beroende på begravningsdjup i sedimenten. Detta kan man använda sig av då man undersöker potentialen för förekomst av kolväten (olja och gas), i lagerföljderna.
I denna avhandling beskrivs en rik och välbevarad sporassociation. Både kryptosporer (framställda av de tidigaste landväxterna) samt trileta sporer (framställda av de första kärlväxterna) har återfunnits. Totalt har 66 olika sporarter identifierats från över-siluriska och devonska sektioner i Skåne och visar på en tidig mångformig flora av landväxter.
Nya och viktiga resultat från Öved Sandstenen presenteras i ett av arbetena då mina resultat baserade på åldersdatering av sporer, visat att den övre delen av Öved Sandstenen är av devonsk ålder. Dessa sediment har tidigare ansetts vara av silurisk ålder.
Under tidsperioden silur och under början av devon var paleokontinenten Baltica, som Sverige tillhörde, täckt av grunda epikontinentala hav. Skåne var täckt av ett grundhav och sporer från landväxter fördes med deltasystemens floder ut till havs och sjönk ner till havets botten då de nådde lugnare vatten. Idag finns dessa sporer från tidiga landväxter bevarade i sediment som förekommer i delar av Skåne och på Gotland. I detta projekt studerades borrkärnor och prover från Skåne och Gotland innehållande fossiliserade växtsporer och annat organiskt material, så som marina mikroorganismer, för att fastställa artrikedomen av sporer i de undersökta proverna. Sporerna studerades med hjälp av ljusmikroskop samt elektronmikroskop. Borrkärnorna togs upp av SGU under 60-talet och har aldrig tidigare studerats med avseende på sporinnehåll. Även i övrigt är studier av siluriska sporer ovanliga från Balticaområdet och kunskapen om de tidiga flororna från denna del av världen är begränsad.
Silurperioden var en mycket intressant period präglad av globala förändringar i miljö och klimat. Under silur hade de första landväxterna etablerat sig och dessa framställde primitiva sporer som en del av sin förökning och de finns till stor del bevarade i de skånska lagerföljderna. Sandstenen i Klintaområdet i Skåne är marin (det vill säga området var täckt av hav) och innehåller förutom sporer från landväxter som spridits ut i havet med floder också marina mikrofossil, till exempel acritarcher. Dessa finns också bevarade i stort antal i lagerföljderna och har studerats tillsammans med sporerna. (Less)
Please use this url to cite or link to this publication:
https://lup.lub.lu.se/record/4174096
- author
- Mehlqvist, Kristina LU
- supervisor
-
- Vivi Vajda LU
- opponent
-
- Wellman, Charles H., Department of Animal and Plant Sciences,University of Sheffield, UK
- organization
- publishing date
- 2013
- type
- Thesis
- publication status
- published
- subject
- keywords
- Spores, early land plants, taxonomy, stratigraphy, biostratigraphy, Silurian
- in
- Litholund theses
- issue
- 23
- pages
- 106 pages
- publisher
- Department of Geology, Lund University
- defense location
- Pangea, Geocentrum II, Department of Geology, Sölvegatan 12 Lund
- defense date
- 2013-12-20 13:00:00
- ISSN
- 1651-6648
- 1651-6648
- ISBN
- 978-91-86746-95-7
- language
- English
- LU publication?
- yes
- id
- e1e649e0-05d2-46d4-bd86-e6de6944ecc0 (old id 4174096)
- date added to LUP
- 2016-04-01 13:59:43
- date last changed
- 2019-05-21 15:04:01
@phdthesis{e1e649e0-05d2-46d4-bd86-e6de6944ecc0,
abstract = {{The Silurian through earliest Devonian, between ca 444 and 412 million years ago, was characterized by significant changes in global climate and environment. At that time, plants and animals had begun to expand the colonization of previous relatively desolate terrestrial landscape. Macrofossils of land plants are very rare from this period because these early land plants lacked large and robust tissues that could be easily fossilized. The spores produced by these early land plants are, therefore, an important tool for resolving the establishment of the early vegetation on Earth. Spore walls are composed of sporopollenin, a complex mix of biopolymers incorporating long chains of fatty acids, phenolics, phenylpropanoids and traces of carotenoids that are, collectively, very resistant to desiccation, pressure and high temperatures. These properties make spores easily preserved as fossils in the sedimentary deposits. Fossil spores can be used as a tool to: study diversity of the terrestrial vegetation, date and correlate sedimentary successions (biostratigraphy), make paleoenvironmental and paleoclimatic interpretations and, finally, assess the potential for hydrocarbon (gas, oil and coal) generation in the sediments.<br/><br>
During the Silurian, the paleocontinent Baltica, of which Sweden was a part, was covered by shallow seas. However, the study area in central and southern Skåne was not too distant from the coast. The sediments here were deposited in foreshore to shoreface environments with water depths no more than a few tens of meters, and in some areas, represented by Lower Devonian successions, possibly even in non-marine environments such as rivers and lakes. Spores from the early land plants were transported by river water into the shallow sea and sank to the bottom as they lost buoyancy. Today these spores from early land plants are preserved in the mid-Paleozoic sedimentary rocks exposed in present day Skåne and on Gotland. <br/><br>
In this project, sedimentary rock samples obtained from drill cores and outcrop at several localities in Skåne and Gotland, were processed by acid dissolution techniques to recover assemblages of organic-walled palynomorphs – mainly plant spores, detrital organic material, and marine palynomorphs. These palynological assemblages were studied by light microscopy to determine the diversity of spore taxa through several short stratigraphic intervals at various sites. Many of the bore cores were drilled by the Swedish Geological Survey during the 1960s and have never been investigated for their fossil spore content. Overall, there have been very few studies of spores from the Silurian of the Baltic region and the knowledge about the composition of the early land floras from this part of the world is sparse. <br/><br>
In this thesis, rich and well-preserved assemblages of early land plant spores are described from both drill core and outcrop samples from Skåne. Both cryptospores (produced by the earliest land plants) and trilete spores (produced by vascular plants) have been recovered. In total, 66 species of both cryptospores and trilete spores were identified in the upper Silurian and Lower Devonian successions of Skåne. These results reveal a rather diverse early terrestrial flora previously unrecognized in the region. Further, a revised stratigraphy for the Öved Sandstone Formation is presented as the c. upper 100 metres of the succession is based on palynostratigraphy of this study shown to represent Devonian strata. <br/><br>
From the Burgsvik Formation, on Gotland, sediments coeval to the studied sections in Skåne, also yielded spores from early land plants. In these beds, the earliest land plant fossil with in situ cryptospores from Baltica was discovered. These remains consist of spore masses with part of the sporangium still preserved, a possible land plant axis, and also more poorly preserved spore masses interpreted to be coprolites (fossil feaces) from arthropods. This last category represents one of the earliest examples of plant-animal interactions globally. <br/><br>
Further, this study reports the oldest evidence of land plants in Sweden. This is in the form of spores identified in Upper Ordovician sedimentary successions in drill core material from Röstånga, Skåne.}},
author = {{Mehlqvist, Kristina}},
isbn = {{978-91-86746-95-7}},
issn = {{1651-6648}},
keywords = {{Spores; early land plants; taxonomy; stratigraphy; biostratigraphy; Silurian}},
language = {{eng}},
number = {{23}},
publisher = {{Department of Geology, Lund University}},
school = {{Lund University}},
series = {{Litholund theses}},
title = {{Early land plant spores from the Paleozoic of Sweden – taxonomy, stratigraphy and paleoenvironments}},
year = {{2013}},
}