scholarly journals Early and Middle Jurassic mires of Bornholm and the Fennoscandian Border Zone: a comparison of depositional environments and vegetation

2003 ◽  
Vol 1 ◽  
pp. 631-656 ◽  
Author(s):  
Henrik I. Petersen ◽  
Lars H. Nielsen ◽  
Eva B. Koppelhus ◽  
Henning S. Sørensen
Keyword(s):  
Organic Matter ◽  
Middle Jurassic ◽  
Significant Proportion ◽  
Open Water ◽  
Lower Jurassic ◽  
Climatic Conditions ◽  
Depositional Environments ◽  
Early Jurassic ◽  
Border Zone ◽  
Peat Formation

Suitable climatic conditions for peat formation existed during Early–Middle Jurassic times in the Fennoscandian Border Zone. Autochthonous peat and allochthonous organic matter were deposited from north Jylland, south-east through the Kattegat and Øresund area, to Skåne and Bornholm. The increase in coal seam abundance and thickness from north Jylland to Bornholm indicates that the most favourable peat-forming conditions were present towards the south-east. Peat formation and deposition of organic-rich muds in the Early Jurassic coastal mires were mainly controlled by a continuous rise of relative sea level governed by subsidence and an overall eustatic rise. Watertable rise repeatedly outpaced the rate of accumulation of organic matter and terminated peat formation by lacustrine or lagoonal flooding. Organic matter accumulated in open-water mires and in continuously waterlogged, anoxic and periodically marine-influenced mires. The latter conditions resulted in huminite-rich coals containing framboidal pyrite. The investigated Lower Jurassic seams correspond to peat and peaty mud deposits that ranged from 0.5–5.7 m in thickness, but were generally less than 3 m thick. It is estimated that on Bornholm, the mires existed on average for c. 1200 years in the Hettangian–Sinemurian and for c. 2300 years in the Late Pliensbachian; the Early Jurassic (Hettangian–Sinemurian) mires in the Øresund area existed for c. 1850 years. Aalenian uplift of the Ringkøbing–Fyn High and major parts of the Danish Basin caused a significant change in the basin configuration and much reduced subsidence in the Fennoscandian Border Zone during the Middle Jurassic. This resulted in a more inland position for the Middle Jurassic mires which on occasion enabled peat accumulation to keep pace with, or temporarily outpace, watertable rise. Thus, peat formation was sometimes sustained for relatively long periods, and the mires may have existed for up to 7000 years in the Øresund area, and up to 19 000 years on Bornholm. The combination of the inland position of the mires, a seasonal climate, and on occasion a peat surface above groundwater level caused temporary oxidation of the peat surfaces and formation of inertinite-rich coals. The spore and pollen assemblages from coal seams and interbedded siliciclastic deposits indicate that the dominant plant groups in both the Early and Middle Jurassic mires were ferns and gymnosperms. However, significant floral differences are evident. In the Lower Jurassic coals, the palynology testifies to a vegetation rich in cycadophytes and coniferophytes (Taxodiaceae family) whereas club mosses were of lesser importance. Conversely, in the Middle Jurassic coals, the palynology indicates an absence of cycadophytes, a minor proportion of coniferophytes (Taxodiaceae) and a significant proportion of club mosses. These variations are probably related to adaptation by different plants to varying environmental conditions, in particular of hydrological character.

scholarly journals Depositional environments of coal and associated siliciclastic sediments in the Lower and Middle Jurassic of Denmark. The Øresund -5, -7, -13, -15 and -18 wells

1994 ◽  
Vol 33 ◽  
pp. 1-55
Author(s):  
Henrik Ingermann Petersen
Keyword(s):  
Organic Matter ◽  
Middle Jurassic ◽  
Saline Water ◽  
Open Water ◽  
Depositional Environments ◽  
Border Zone ◽  
Coal Seams ◽  
Raised Bog ◽  
Type 3 ◽  
Siliciclastic Sediments

Five cored wells located in the Fennoscandian Border Zone in the Øresund area, Denmark, encountered Lower or Middle Jurassic coal-bearing strata; the coal seams are Lignite to Sub-bituminous A/High Vol. Bituminous C in rank. A number of shallowing-upward units are recognized in the five wells. Each unit is capped by a coal seam. Correlation of these shallowing-upward units between wells is difficult on the basis of available biostratigraphy and log data. Seven of the coal seams result from establishment of peatforming conditions due to infilling of freshwater lakes, whereas the last two of the coal seams result from peat accumulation on top of restricted brackish lagoon or bay sediments. However, only one of the latter two seams accumulated in an environment influenced by saline water. Hence, the investigated coals represent almost entirely freshwater peat-forming environments. Three main types of environments are defined: 1) Type 1 is a sparsely vegetated open water swamp; it is represented by a limnic facies. The deposit is typically a carbonaceous claystone with a high content of allochthonous organic matter; 2) Type 2 is a densely vegetated rheotrophic, nutrient-rich and anoxic swamp; it is represented by a limnotelmatic to telmatic facies. The coal has a very high content of humified organic matter; 3) Type 3, subdivided into the types 3a and 3b, is the driest environment of the three types. Type 3a is a desiccated ombrotrophic raised bog represented by a terrestrial facies. It is strongly influenced by a fluctuating watertable. The coals contain a high content of inertinite that generally shows a low reflectance. Type 3b is a mesotrophic to ombrotrophic domed bog; the environment alternates between dry oxidizing conditions and wet conditions. It is represented by a telmatic to terrestrial facies. In general, the three types of environments form ecosystems characterized by the groundwater influence, nutrient supply, and vegetation. Successions representing the hydrological evolution towards drier conditions due to vertical peat accretion are recognized in some of the seams. The vegetation was small-statured and consisted of a prominent herbaceous type of flora, shrub-like plants, smaller arboreous plants and, to a lesser extent, larger plants.

Provenance of Jurassic sedimentary rocks of south-central Quesnellia, British Columbia: implications for paleogeography

2004 ◽  
Vol 41 (1) ◽  
pp. 103-125 ◽  
Author(s):  
Nathan T Petersen ◽  
Paul L Smith ◽  
James K Mortensen ◽  
Robert A Creaser ◽  
Howard W Tipper
Keyword(s):  
Detrital Zircon ◽  
Middle Jurassic ◽  
Sedimentary Rocks ◽  
Source Area ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Late Triassic ◽  
Nd Isotopes ◽  
South Central ◽  
History Of

Jurassic sedimentary rocks of southern to central Quesnellia record the history of the Quesnellian magmatic arc and reflect increasing continental influence throughout the Jurassic history of the terrane. Standard petrographic point counts, geochemistry, Sm–Nd isotopes and detrital zircon geochronology, were employed to study provenance of rocks obtained from three areas of the terrane. Lower Jurassic sedimentary rocks, classified by inferred proximity to their source areas as proximal or proximal basin are derived from an arc source area. Sandstones of this age are immature. The rocks are geochemically and isotopically primitive. Detrital zircon populations, based on a limited number of analyses, have homogeneous Late Triassic or Early Jurassic ages, reflecting local derivation from Quesnellian arc sources. Middle Jurassic proximal and proximal basin sedimentary rocks show a trend toward more evolved mature sediments and evolved geochemical characteristics. The sandstones show a change to more mature grain components when compared with Lower Jurassic sedimentary rocks. There is a decrease in εNdT values of the sedimentary rocks and Proterozoic detrital zircon grains are present. This change is probably due to a combination of two factors: (1) pre-Middle Jurassic erosion of the Late Triassic – Early Jurassic arc of Quesnellia, making it a less dominant source, and (2) the increase in importance of the eastern parts of Quesnellia and the pericratonic terranes, such as Kootenay Terrane, both with characteristically more evolved isotopic values. Basin shale environments throughout the Jurassic show continental influence that is reflected in the evolved geochemistry and Sm–Nd isotopes of the sedimentary rocks. The data suggest southern Quesnellia received material from the North American continent throughout the Jurassic but that this continental influence was diluted by proximal arc sources in the rocks of proximal derivation. The presence of continent-derived material in the distal sedimentary rocks of this study suggests that southern Quesnellia is comparable to known pericratonic terranes.

Compositions, sources and depositional environments of organic matter from the Middle Jurassic clays of Poland

2007 ◽  
Vol 22 (11) ◽  
pp. 2456-2485 ◽  
Author(s):  
Leszek Marynowski ◽  
Michał Zatoń ◽  
Bernd R.T. Simoneit ◽  
Angelika Otto ◽  
Mariusz O. Jędrysek ◽  
...  
Keyword(s):  
Organic Matter ◽  
Middle Jurassic ◽  
Depositional Environments

Uncommon preservation of dinosaur footprints in a tidal breccia: Eubrontes giganteus from the Early Jurassic Mongisty tracksite of Aveyron, southern France

2021 ◽  
pp. 1-18
Author(s):  
Jean-David Moreau ◽  
Jacques Sciau ◽  
Georges Gand ◽  
Emmanuel Fara
Keyword(s):  
Scale Up ◽  
Lower Jurassic ◽  
Depositional Environments ◽  
Early Jurassic ◽  
Coarse Grained ◽  
Southern France ◽  
Fine Grained ◽  
The North ◽  
Dinosaur Tracks ◽  
First Time

Abstract A recent excavation yielded 118 large tridactyl footprints in the Lower Jurassic Dolomitic Formation of the Causses Basin, at Mongisty in southern France. Most of the tracks are ascribed to Eubrontes giganteus Hitchcock, 1845. They are preserved on a surface of 53 m2 and form parallel rows with a preferential orientation towards the north. Such an abundance and density of E. giganteus is observed for the first time in the Early Jurassic from the Causses Basin. Sedimentological and ichnotaphonomical analyses show that the footprints were made at different time intervals, thus excluding the passage of a large group. In contrast to all other tracksites from the Dolomitic Formation, where tracks are preserved in fine-grained sediments corresponding to low-energy depositional palaeoenvironments, the tracks from Mongisty are preserved in coarse-grained sediment which is a matrix- to clast-supported breccia. Clasts consist of angular to sub-rounded, millimetric to centimetric-scale (up to 2 cm), poorly sorted, randomly oriented, homogeneous dolostone intraclasts floating in a dolomudstone matrix. Sedimentological analysis shows that the depositional environments of Mongisty varied from subtidal to intertidal/supratidal settings in a large and protected flat marsh. The lithology of the track-bearing surfaces indicates that the mudflat of the Causses Basin was sporadically affected by large mud flows that reworked and redeposited mudstone intraclasts coming from the erosion of upstream, dry and partially lithified mud beds. Throughout the world, this type of preservation of dinosaur tracks in tidal matrix- to clast-supported breccias remains rare.

scholarly journals Paleoclimatic and Redox Condition Changes during Early-Middle Jurassic in the Yili Basin, Northwest China

Minerals ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 675
Author(s):  
Hui Chao ◽  
Mingcai Hou ◽  
Wenjian Jiang ◽  
Haiyang Cao ◽  
Xiaolin Chang ◽  
...  
Keyword(s):  
Middle Jurassic ◽  
Northwest China ◽  
Early Jurassic ◽  
Coal Seams ◽  
High Productivity ◽  
Fine Grained ◽  
Palynological Assemblages ◽  
Continental Arc ◽  
Terrestrial Sediments ◽  
Peat Formation

The Jurassic was mainly a “greenhouse” period characterized by global warming and by significant peat accumulations in some continental basins. However, studies of Jurassic climate and environments have mainly focused on marine records and only a few on terrestrial sediments. Yili Basin, a mid-latitude terrestrial basin in present Northwest China, included accumulation of the important recoverable coal seams. In this study, geological data, clay mineral analysis, and palynological assemblages were employed on fine-grained samples from the Su’asugou section in southern Yili Basin. The factors (paleoclimate, depositional conditions, and paleo-vegetation) impacting peat accumulation were investigated. The results suggest that the siliciclastics may have been derived from exposed Carboniferous rocks in a continental arc environment. A warm and humid paleoclimate in the Yili basin dominated during the early-Early Jurassic deposition of the Badaowan Formation and the Middle Jurassic deposition of the Xishanyao Formation. This climate contributed to high sedimentary rates and to a high productivity of peat-forming paleo-vegetation that was preserved under dysoxic conditions. In contrast, during the late-Early Jurassic between these two formations, the Sangonghe Formation was an interval of relatively aridity that included red beds preserved under more hypoxic sedimentary conditions, and with an interruption in peat formation and preservation.

scholarly journals A backstepping, fluviatile-paralic-marine succession, Sinemurian, Lower Jurassic, Skåne, southern Sweden

1999 ◽  
Vol 46 ◽  
pp. 1-12
Author(s):  
M. Erlström ◽  
U. Sivhed ◽  
F. Surlyk
Keyword(s):  
Lower Jurassic ◽  
Depositional Environments ◽  
Border Zone ◽  
Time Interval ◽  
Short Time Interval ◽  
The North ◽  
Sedimentary Evolution ◽  
Braided Streams ◽  
The Individual ◽  
A Minor

A temporal exposure of a Lower Sinemurian succession of fluviatile, coastal plain and marine sediments was accessible for study during a short time interval in 1997 at Örby, NW Skåne, Sweden. The succession adds significantly to the knowledge and understanding of the Sinemurian sedimentary evolution of the Fennoscandian Border Zone and the north-eastern margin of the Danish Basin. The top of the section overlaps the base of a section previously exposed at the nearby quarry at Gantofta. The combined evidence from Örby, Gantofta and a few borings shows that Sinemurian sedimentation took place during marked stepwise transgression. This is recorded by backstepping of the depositional environments from braided streams, over lakes and swamps, to estuarine and finally fully marine, offshore conditions. The sedimentary packages of the individual systems are well defined and separated mainly by sharp boundaries representing lacustrine, estuarine and marine flooding and ravinement surfaces. A regional sea-level rise punctuated by a minor fall is suggested to be the main factor controlling Early Jurassic basin evolution of the northeastern margin of the Danish Basin and the Fennoscandian Border Zone.

Petroleum potential and depositional environments of Middle Jurassic coals and non-marine deposits, Danish Central Graben, with special reference to the Søgne Basin

1998 ◽  
pp. 1-80 ◽  
Author(s):  
Henrik I. Petersen ◽  
Jan Andsbjerg ◽  
Jørgen A. Bojesen-Koefoed ◽  
Hans P. Nytoft ◽  
Per Rosenberg
Keyword(s):  
Organic Matter ◽  
Special Reference ◽  
Sea Level ◽  
Middle Jurassic ◽  
Depositional Environments ◽  
Thermal Maturity ◽  
Coal Seams ◽  
Petroleum Potential ◽  
Marine Deposits ◽  
Marine Influence

NOTE: This monograph was published in a former series of GEUS Bulletin. Please use the original series name when citing this monograph. For example: Petersen, H. I., Andsbjerg, J., Bojesen-Koefoed, J. A., Nytoft, H. P., & Rosenberg, P. (1998). Petroleum potential and depositional environments of Middle Jurassic coals and non-marine deposits, Danish Central Graben, with special reference to the Søgne Basin. Geology of Denmark Survey Bulletin, 36, 1-80. https://doi.org/10.34194/dgub.v36.5022 _______________ New data from five wells in the Søgne Basin, Danish Central Graben of the North Sea - West Lulu-1, West Lulu-3, Lulu-1, Amalie-1 and Cleo-1 - together with previously released data from the West Lulu-2 well, show that the cumulative thickness of the Bryne Formation coal seams decreases towards the palaeo-shoreline from 5.05 m to 0.60 m, and that the seams have varying extents. Their overall organic petrographic and geochemical composition reflects the palaeoenvironmental conditions in the precursor mires, in particular the rate of rise in the water table, principally related to the relative rise in sea level, and the degree of marine influence. Laterally towards the palaeo-shoreline, all coal seams have increased proportions of C27 steranes and higher C35-homohopane indices suggesting stronger marine influence on the coastal reaches of the ancient mires. In each well it is also observed that coal seams formed during accelerated relative sea-level rise (T-seams) are characterised by higher contents of sterane C27 and higher C35-homohopane indices than seams formed during slower rates of base-level rise (R-seams). The most landward and freshwater-influenced parts of the seams have higher proportions of sterane C29 and the highest Pr/Ph ratios. The coals, with respect to thermal maturity, are well within the oil window, except in the Amalie-1 well where they are more mature. The largest average hydrogen indices and thermally extracted and generated bitumen yields are obtained from the T-seams. However, generally an increase in the hydrogen index is recorded in a seaward direction for all seams. Multivariate regression analysis demonstrates that collotelinite, telinite, the vitrinite maceral group, vitrinite-rich microlithotypes and the TOC content have a significant positive influence on the remaining generative potential represented by S2. Pyrolysis-gas chromatography reveals that during maturation the coals will generate from 72.4 to 82.0% oil-like components and only 18.0 to 27.6% gas. However, this does not necessarily imply that all of these oil-like components can be expelled to form a crude oil accumulation. Distribution of C27–29 regular steranes shows good correlation between extracts of Bryne Formation coals and oils/condensates present in Bryne Formation sandstones. The sum of evidence indicates that the coals in the Søgne Basin have generated and are still capable of generating liquid and gaseous petroleum, but with respect to petroleum generation potential, they are not as good as the documented oil-prone Middle Jurassic coals from North-East Greenland and Tertiary coals from Asia. Mudstones intercalated with the Bryne Formation coals have a similar or lower generative potential as the coals. In areas outside the Søgne Basin, the coastal plain deposits of the Central Graben Group contain predominantly terrestrial-derived kerogen type III or IIb. The thermal maturity of the organic matter ranges from close to or within the peak oil generation range in the oil window (Alma-1x, Anne-3a and M-8 well) to the late oil window (Elly-3 and Falk-1 wells) or close to the end of the oil window (Skjold Flank-1 well). Only a limited generative potential remains in Elly-3, but the kerogen may initially have possessed a good petroleum potential. In the Falk-1 well, a good generative capacity still remains. The kerogen in Skjold Flank-1 may possess the capability to generate condensate and gas, whereas the organic matter in the Alma-1x, Anne-3a and M-8 wells generally exhibits a poor petroleum generative potential.  

Early Jurassic (Toarcian) warming identified from lacustrine sediments of eastern Liaoning, China

2020 ◽  
pp. 1-15
Author(s):  
Qian Zhang ◽  
Enpu Gong ◽  
Yongli Zhang ◽  
Changqing Guan
Keyword(s):  
Organic Carbon ◽  
Climate Warming ◽  
Middle Jurassic ◽  
Lacustrine Sediments ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Total Organic Nitrogen ◽  
Carbon Isotopic ◽  
Carbon Isotope Excursion ◽  
Continental Climate

Abstract This study focuses on the Tianshifu Basin, eastern Liaoning, China, which is filled with Lower–Middle Jurassic fluviolacustrine sediments rich in macroplants. Our aim is to explore the continental climate features of the late Early Jurassic period. The composition of the Early–Middle Jurassic flora and the carbon isotopic ratios of organic matter, total organic carbon, total organic nitrogen and sulphur of the rock samples from the Changliangzi section (the upper part of the Lower Jurassic deposits) have been investigated. Based on the flora, eastern Liaoning was generally characterized by temperate and humid conditions during the Early–Middle Jurassic period, but with rising temperatures during late Early Jurassic time. The sediments of the Changliangzi section show a transformation from shallow-lake facies to deep-lake facies. A positive organic carbon isotope excursion correlates with the deepening of this palaeolake, considered to be caused by climate warming. The late Early Jurassic climate warming indicated by floral and isotopic evidence corresponds to the climatic events recorded elsewhere in marine and continental sequences during the Toarcian Age, the so-called Toarcian Anoxic event, and may be associated with enhanced global greenhouse warming. This study provides new continental data supporting global warming during the late Early Jurassic period.

Characterisation of production of organic rich topsoil from sludge

2000 ◽  
Vol 42 (9) ◽  
pp. 195-201 ◽  
Author(s):  
P. Andreasen ◽  
P. B. Mortensen ◽  
A. Stubsgaard ◽  
B. Langdahl
Keyword(s):  
Organic Matter ◽  
Oxygen Consumption ◽  
Oxygen Transport ◽  
Mineral Soil ◽  
Climatic Conditions ◽  
Growth Media ◽  
Soil Mixture ◽  
Water Suspension ◽  
Aerobic Process ◽  
Stable Product

The stabilisation of a sludge-mineral soil mixture and a method to evaluate the state of stabilisation were investigated. The organic matter and nitrogen content are reduced up to 50% during a stabilisation process of three months under Danish climatic conditions. The stabilisation was shown to be an aerobic process limited by oxygen transport within the mixture. The degree of stabilisation was evaluated by oxygen consumption in a water suspension and the results showed that a stable product was achieved when oxygen consumption was stable and in the level of natural occurring aerobic soils (0.1 mgO2/(g DS*hr). The study thereby demonstrates that a stability of a growth media can be controlled by the oxygen consumption method tested.

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