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  • 1
    Publication Date: 1986-01-01
    Print ISSN: 0149-1423
    Electronic ISSN: 1943-2674
    Topics: Geosciences
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  • 2
    Publication Date: 2009-07-03
    Description: Schizophrenia is a complex disorder, caused by both genetic and environmental factors and their interactions. Research on pathogenesis has traditionally focused on neurotransmitter systems in the brain, particularly those involving dopamine. Schizophrenia has been considered a separate disease for over a century, but in the absence of clear biological markers, diagnosis has historically been based on signs and symptoms. A fundamental message emerging from genome-wide association studies of copy number variations (CNVs) associated with the disease is that its genetic basis does not necessarily conform to classical nosological disease boundaries. Certain CNVs confer not only high relative risk of schizophrenia but also of other psychiatric disorders. The structural variations associated with schizophrenia can involve several genes and the phenotypic syndromes, or the 'genomic disorders', have not yet been characterized. Single nucleotide polymorphism (SNP)-based genome-wide association studies with the potential to implicate individual genes in complex diseases may reveal underlying biological pathways. Here we combined SNP data from several large genome-wide scans and followed up the most significant association signals. We found significant association with several markers spanning the major histocompatibility complex (MHC) region on chromosome 6p21.3-22.1, a marker located upstream of the neurogranin gene (NRGN) on 11q24.2 and a marker in intron four of transcription factor 4 (TCF4) on 18q21.2. Our findings implicating the MHC region are consistent with an immune component to schizophrenia risk, whereas the association with NRGN and TCF4 points to perturbation of pathways involved in brain development, memory and cognition.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3077530/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3077530/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Stefansson, Hreinn -- Ophoff, Roel A -- Steinberg, Stacy -- Andreassen, Ole A -- Cichon, Sven -- Rujescu, Dan -- Werge, Thomas -- Pietilainen, Olli P H -- Mors, Ole -- Mortensen, Preben B -- Sigurdsson, Engilbert -- Gustafsson, Omar -- Nyegaard, Mette -- Tuulio-Henriksson, Annamari -- Ingason, Andres -- Hansen, Thomas -- Suvisaari, Jaana -- Lonnqvist, Jouko -- Paunio, Tiina -- Borglum, Anders D -- Hartmann, Annette -- Fink-Jensen, Anders -- Nordentoft, Merete -- Hougaard, David -- Norgaard-Pedersen, Bent -- Bottcher, Yvonne -- Olesen, Jes -- Breuer, Rene -- Moller, Hans-Jurgen -- Giegling, Ina -- Rasmussen, Henrik B -- Timm, Sally -- Mattheisen, Manuel -- Bitter, Istvan -- Rethelyi, Janos M -- Magnusdottir, Brynja B -- Sigmundsson, Thordur -- Olason, Pall -- Masson, Gisli -- Gulcher, Jeffrey R -- Haraldsson, Magnus -- Fossdal, Ragnheidur -- Thorgeirsson, Thorgeir E -- Thorsteinsdottir, Unnur -- Ruggeri, Mirella -- Tosato, Sarah -- Franke, Barbara -- Strengman, Eric -- Kiemeney, Lambertus A -- Genetic Risk and Outcome in Psychosis (GROUP) -- Melle, Ingrid -- Djurovic, Srdjan -- Abramova, Lilia -- Kaleda, Vasily -- Sanjuan, Julio -- de Frutos, Rosa -- Bramon, Elvira -- Vassos, Evangelos -- Fraser, Gillian -- Ettinger, Ulrich -- Picchioni, Marco -- Walker, Nicholas -- Toulopoulou, Timi -- Need, Anna C -- Ge, Dongliang -- Yoon, Joeng Lim -- Shianna, Kevin V -- Freimer, Nelson B -- Cantor, Rita M -- Murray, Robin -- Kong, Augustine -- Golimbet, Vera -- Carracedo, Angel -- Arango, Celso -- Costas, Javier -- Jonsson, Erik G -- Terenius, Lars -- Agartz, Ingrid -- Petursson, Hannes -- Nothen, Markus M -- Rietschel, Marcella -- Matthews, Paul M -- Muglia, Pierandrea -- Peltonen, Leena -- St Clair, David -- Goldstein, David B -- Stefansson, Kari -- Collier, David A -- 089061/Wellcome Trust/United Kingdom -- 1R01HL087679-01/HL/NHLBI NIH HHS/ -- PDA/02/06/016/Department of Health/United Kingdom -- R01 MH078075/MH/NIMH NIH HHS/ -- England -- Nature. 2009 Aug 6;460(7256):744-7. doi: 10.1038/nature08186. Epub 2009 Jul 1.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE genetics, Sturlugata 8, IS-101 Reykjavik, Iceland.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/19571808" target="_blank"〉PubMed〈/a〉
    Keywords: Basic Helix-Loop-Helix Leucine Zipper Transcription Factors ; Chromosomes, Human, Pair 11/genetics ; Chromosomes, Human, Pair 18/genetics ; Chromosomes, Human, Pair 6/genetics ; DNA-Binding Proteins/genetics ; Genetic Markers/genetics ; Genetic Predisposition to Disease/*genetics ; Genome, Human/genetics ; Genome-Wide Association Study ; Genotype ; Humans ; Major Histocompatibility Complex/genetics ; Neurogranin/genetics ; Polymorphism, Single Nucleotide/*genetics ; Schizophrenia/*genetics/immunology ; Transcription Factors/genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 3
    Publication Date: 2010-10-29
    Description: Meiotic recombinations contribute to genetic diversity by yielding new combinations of alleles. Recently, high-resolution recombination maps were inferred from high-density single-nucleotide polymorphism (SNP) data using linkage disequilibrium (LD) patterns that capture historical recombination events. The use of these maps has been demonstrated by the identification of recombination hotspots and associated motifs, and the discovery that the PRDM9 gene affects the proportion of recombinations occurring at hotspots. However, these maps provide no information about individual or sex differences. Moreover, locus-specific demographic factors like natural selection can bias LD-based estimates of recombination rate. Existing genetic maps based on family data avoid these shortcomings, but their resolution is limited by relatively few meioses and a low density of markers. Here we used genome-wide SNP data from 15,257 parent-offspring pairs to construct the first recombination maps based on directly observed recombinations with a resolution that is effective down to 10 kilobases (kb). Comparing male and female maps reveals that about 15% of hotspots in one sex are specific to that sex. Although male recombinations result in more shuffling of exons within genes, female recombinations generate more new combinations of nearby genes. We discover novel associations between recombination characteristics of individuals and variants in the PRDM9 gene and we identify new recombination hotspots. Comparisons of our maps with two LD-based maps inferred from data of HapMap populations of Utah residents with ancestry from northern and western Europe (CEU) and Yoruba in Ibadan, Nigeria (YRI) reveal population differences previously masked by noise and map differences at regions previously described as targets of natural selection.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, Augustine -- Thorleifsson, Gudmar -- Gudbjartsson, Daniel F -- Masson, Gisli -- Sigurdsson, Asgeir -- Jonasdottir, Aslaug -- Walters, G Bragi -- Jonasdottir, Adalbjorg -- Gylfason, Arnaldur -- Kristinsson, Kari Th -- Gudjonsson, Sigurjon A -- Frigge, Michael L -- Helgason, Agnar -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- England -- Nature. 2010 Oct 28;467(7319):1099-103. doi: 10.1038/nature09525.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland. kong@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20981099" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Chromosomes, Human/*genetics ; DNA-Binding Proteins/genetics ; Europe/ethnology ; Exons/genetics ; Female ; Genetics, Population ; Haplotypes/genetics ; Heterozygote ; Histone-Lysine N-Methyltransferase/genetics ; Humans ; Linkage Disequilibrium/genetics ; Male ; Meiosis/genetics ; Nigeria/ethnology ; Pedigree ; Polymorphism, Single Nucleotide/genetics ; Recombination, Genetic/*genetics ; Sample Size ; Selection, Genetic/genetics ; *Sex Characteristics ; Utah
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 4
    Publication Date: 2012-08-24
    Description: Mutations generate sequence diversity and provide a substrate for selection. The rate of de novo mutations is therefore of major importance to evolution. Here we conduct a study of genome-wide mutation rates by sequencing the entire genomes of 78 Icelandic parent-offspring trios at high coverage. We show that in our samples, with an average father's age of 29.7, the average de novo mutation rate is 1.20 x 10(-8) per nucleotide per generation. Most notably, the diversity in mutation rate of single nucleotide polymorphisms is dominated by the age of the father at conception of the child. The effect is an increase of about two mutations per year. An exponential model estimates paternal mutations doubling every 16.5 years. After accounting for random Poisson variation, father's age is estimated to explain nearly all of the remaining variation in the de novo mutation counts. These observations shed light on the importance of the father's age on the risk of diseases such as schizophrenia and autism.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548427/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3548427/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, Augustine -- Frigge, Michael L -- Masson, Gisli -- Besenbacher, Soren -- Sulem, Patrick -- Magnusson, Gisli -- Gudjonsson, Sigurjon A -- Sigurdsson, Asgeir -- Jonasdottir, Aslaug -- Jonasdottir, Adalbjorg -- Wong, Wendy S W -- Sigurdsson, Gunnar -- Walters, G Bragi -- Steinberg, Stacy -- Helgason, Hannes -- Thorleifsson, Gudmar -- Gudbjartsson, Daniel F -- Helgason, Agnar -- Magnusson, Olafur Th -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- MH071425/MH/NIMH NIH HHS/ -- R01 MH071425/MH/NIMH NIH HHS/ -- England -- Nature. 2012 Aug 23;488(7412):471-5. doi: 10.1038/nature11396.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics, Sturlugata 8, 101 Reykjavik, Iceland. kong@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/22914163" target="_blank"〉PubMed〈/a〉
    Keywords: Adult ; Autistic Disorder/epidemiology/etiology/*genetics ; Chromosomes, Human/genetics ; Female ; *Genetic Predisposition to Disease ; Genome, Human/genetics ; Humans ; Iceland/epidemiology ; Male ; Middle Aged ; Mothers ; *Mutation Rate ; Ovum/metabolism ; *Paternal Age ; Pedigree ; Polymorphism, Single Nucleotide/genetics ; Risk Factors ; Schizophrenia/epidemiology/etiology/*genetics ; Selection, Genetic/genetics ; Sequence Analysis, DNA ; Spermatozoa/metabolism ; Young Adult
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 5
    Publication Date: 2013-05-07
    Description: Low bone mineral density (BMD) is used as a parameter of osteoporosis. Genome-wide association studies of BMD have hitherto focused on BMD as a quantitative trait, yielding common variants of small effects that contribute to the population diversity in BMD. Here we use BMD as a dichotomous trait, searching for variants that may have a direct effect on the risk of pathologically low BMD rather than on the regulation of BMD in the healthy population. Through whole-genome sequencing of Icelandic individuals, we found a rare nonsense mutation within the leucine-rich-repeat-containing G-protein-coupled receptor 4 (LGR4) gene (c.376C〉T) that is strongly associated with low BMD, and with osteoporotic fractures. This mutation leads to termination of LGR4 at position 126 and fully disrupts its function. The c.376C〉T mutation is also associated with electrolyte imbalance, late onset of menarche and reduced testosterone levels, as well as an increased risk of squamous cell carcinoma of the skin and biliary tract cancer. Interestingly, the phenotype of carriers of the c.376C〉T mutation overlaps that of Lgr4 mutant mice.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Styrkarsdottir, Unnur -- Thorleifsson, Gudmar -- Sulem, Patrick -- Gudbjartsson, Daniel F -- Sigurdsson, Asgeir -- Jonasdottir, Aslaug -- Jonasdottir, Adalbjorg -- Oddsson, Asmundur -- Helgason, Agnar -- Magnusson, Olafur T -- Walters, G Bragi -- Frigge, Michael L -- Helgadottir, Hafdis T -- Johannsdottir, Hrefna -- Bergsteinsdottir, Kristin -- Ogmundsdottir, Margret H -- Center, Jacqueline R -- Nguyen, Tuan V -- Eisman, John A -- Christiansen, Claus -- Steingrimsson, Erikur -- Jonasson, Jon G -- Tryggvadottir, Laufey -- Eyjolfsson, Gudmundur I -- Theodors, Asgeir -- Jonsson, Thorvaldur -- Ingvarsson, Thorvaldur -- Olafsson, Isleifur -- Rafnar, Thorunn -- Kong, Augustine -- Sigurdsson, Gunnar -- Masson, Gisli -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- HL-102923/HL/NHLBI NIH HHS/ -- HL-102924/HL/NHLBI NIH HHS/ -- HL-102925/HL/NHLBI NIH HHS/ -- HL-102926/HL/NHLBI NIH HHS/ -- HL-103010/HL/NHLBI NIH HHS/ -- England -- Nature. 2013 May 23;497(7450):517-20. doi: 10.1038/nature12124. Epub 2013 May 5.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE Genetics/Amgen, 101 Reykjavik, Iceland. unnurth@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/23644456" target="_blank"〉PubMed〈/a〉
    Keywords: Animals ; Australia ; Biliary Tract Neoplasms/*genetics ; Bone Density/*genetics ; Carcinoma, Squamous Cell/*genetics ; Codon, Nonsense/*genetics ; Denmark ; Down-Regulation/genetics ; Female ; Heterozygote ; Humans ; Iceland ; Male ; Menarche/genetics ; Mice ; Mice, Knockout ; Osteoporotic Fractures/*genetics ; Phenotype ; Receptors, G-Protein-Coupled/chemistry/deficiency/*genetics/metabolism ; Skin Neoplasms/*genetics ; Testosterone/analysis ; Water-Electrolyte Imbalance/*genetics
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 6
    Publication Date: 2009-12-18
    Description: Effects of susceptibility variants may depend on from which parent they are inherited. Although many associations between sequence variants and human traits have been discovered through genome-wide associations, the impact of parental origin has largely been ignored. Here we show that for 38,167 Icelanders genotyped using single nucleotide polymorphism (SNP) chips, the parental origin of most alleles can be determined. For this we used a combination of genealogy and long-range phasing. We then focused on SNPs that associate with diseases and are within 500 kilobases of known imprinted genes. Seven independent SNP associations were examined. Five-one with breast cancer, one with basal-cell carcinoma and three with type 2 diabetes-have parental-origin-specific associations. These variants are located in two genomic regions, 11p15 and 7q32, each harbouring a cluster of imprinted genes. Furthermore, we observed a novel association between the SNP rs2334499 at 11p15 and type 2 diabetes. Here the allele that confers risk when paternally inherited is protective when maternally transmitted. We identified a differentially methylated CTCF-binding site at 11p15 and demonstrated correlation of rs2334499 with decreased methylation of that site.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746295/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉   〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3746295/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Kong, Augustine -- Steinthorsdottir, Valgerdur -- Masson, Gisli -- Thorleifsson, Gudmar -- Sulem, Patrick -- Besenbacher, Soren -- Jonasdottir, Aslaug -- Sigurdsson, Asgeir -- Kristinsson, Kari Th -- Jonasdottir, Adalbjorg -- Frigge, Michael L -- Gylfason, Arnaldur -- Olason, Pall I -- Gudjonsson, Sigurjon A -- Sverrisson, Sverrir -- Stacey, Simon N -- Sigurgeirsson, Bardur -- Benediktsdottir, Kristrun R -- Sigurdsson, Helgi -- Jonsson, Thorvaldur -- Benediktsson, Rafn -- Olafsson, Jon H -- Johannsson, Oskar Th -- Hreidarsson, Astradur B -- Sigurdsson, Gunnar -- DIAGRAM Consortium -- Ferguson-Smith, Anne C -- Gudbjartsson, Daniel F -- Thorsteinsdottir, Unnur -- Stefansson, Kari -- 077016/Wellcome Trust/United Kingdom -- 090532/Wellcome Trust/United Kingdom -- G9723500/Medical Research Council/United Kingdom -- K08 AR055688/AR/NIAMS NIH HHS/ -- MC_U106179471/Medical Research Council/United Kingdom -- MC_U106179474/Medical Research Council/United Kingdom -- MC_U127592696/Medical Research Council/United Kingdom -- R01 DK029867/DK/NIDDK NIH HHS/ -- England -- Nature. 2009 Dec 17;462(7275):868-74. doi: 10.1038/nature08625.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉deCODE genetics, Sturlugata 8, 101 Reykjavik, Iceland. kong@decode.is〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/20016592" target="_blank"〉PubMed〈/a〉
    Keywords: Alleles ; Binding Sites ; Breast Neoplasms/genetics ; Carcinoma, Basal Cell/genetics ; Chromosomes, Human, Pair 11/genetics ; Chromosomes, Human, Pair 7/genetics ; DNA Methylation/genetics ; Diabetes Mellitus, Type 2/genetics ; *Fathers ; Female ; Genetic Predisposition to Disease/*genetics ; Genome, Human/genetics ; Genomic Imprinting/genetics ; Haplotypes ; Humans ; Iceland ; Male ; *Mothers ; Pedigree ; Polymorphism, Single Nucleotide/*genetics ; Repressor Proteins/metabolism
    Print ISSN: 0028-0836
    Electronic ISSN: 1476-4687
    Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics
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  • 7
    Publication Date: 2012-11-04
    Description: After the generation of DNA double-strand breaks (DSBs), poly(ADP-ribose) polymerase-1 (PARP-1) is one of the first proteins to be recruited and activated through its binding to the free DNA ends. Upon activation, PARP-1 uses NAD + to generate large amounts of poly(ADP-ribose) (PAR), which facilitates the recruitment of DNA repair factors. Here, we identify the RNA-binding protein NONO, a partner protein of SFPQ, as a novel PAR-binding protein. The protein motif being primarily responsible for PAR-binding is the RNA recognition motif 1 (RRM1), which is also crucial for RNA-binding, highlighting a competition between RNA and PAR as they share the same binding site. Strikingly, the in vivo recruitment of NONO to DNA damage sites completely depends on PAR, generated by activated PARP-1. Furthermore, we show that upon PAR-dependent recruitment, NONO stimulates nonhomologous end joining (NHEJ) and represses homologous recombination (HR) in vivo . Our results therefore place NONO after PARP activation in the context of DNA DSB repair pathway decision. Understanding the mechanism of action of proteins that act in the same pathway as PARP-1 is crucial to shed more light onto the effect of interference on PAR-mediated pathways with PARP inhibitors, which have already reached phase III clinical trials but are until date poorly understood.
    Print ISSN: 0305-1048
    Electronic ISSN: 1362-4962
    Topics: Biology
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  • 8
    Publication Date: 2012-10-31
    Description: Submarine sediment density flows are one of the most important processes for moving sediment across our planet, yet they are extremely difficult to monitor directly. The speed of long run-out submarine density flows has been measured directly in just five locations worldwide and their sediment concentration has never been measured directly. The only record of most density flows is their sediment deposit. This article summarizes the processes by which density flows deposit sediment and proposes a new single classification for the resulting types of deposit. Colloidal properties of fine cohesive mud ensure that mud deposition is complex, and large volumes of mud can sometimes pond or drain-back for long distances into basinal lows. Deposition of ungraded mud (T E-3 ) most probably finally results from en masse consolidation in relatively thin and dense flows, although initial size sorting of mud indicates earlier stages of dilute and expanded flow. Graded mud (T E-2 ) and finely laminated mud (T E-1 ) most probably result from floc settling at lower mud concentrations. Grain-size breaks beneath mud intervals are commonplace, and record bypass of intermediate grain sizes due to colloidal mud behaviour. Planar-laminated (T D ) and ripple cross-laminated (T C ) non-cohesive silt or fine sand is deposited by dilute flow, and the external deposit shape is consistent with previous models of spatial decelerating (dissipative) dilute flow. A grain-size break beneath the ripple cross-laminated (T C ) interval is common, and records a period of sediment reworking (sometimes into dunes) or bypass. Finely planar-laminated sand can be deposited by low-amplitude bed waves in dilute flow (T B-1 ), but it is most likely to be deposited mainly by high-concentration near-bed layers beneath high-density flows (T B-2 ). More widely spaced planar lamination (T B-3 ) occurs beneath massive clean sand (T A ), and is also formed by high-density turbidity currents. High-density turbidite deposits (T A , T B-2 and T B-3 ) have a tabular shape consistent with hindered settling, and are typically overlain by a more extensive drape of low-density turbidite (T D and T C ,). This core and drape shape suggests that events sometimes comprise two distinct flow components. Massive clean sand is less commonly deposited en masse by liquefied debris flow (D CS ), in which case the clean sand is ungraded or has a patchy grain-size texture. Clean-sand debrites can extend for several tens of kilometres before pinching out abruptly. Up-current transitions suggest that clean-sand debris flows sometimes form via transformation from high-density turbidity currents. Cohesive debris flows can deposit three types of ungraded muddy sand that may contain clasts. Thick cohesive debrites tend to occur in more proximal settings and extend from an initial slope failure. Thinner and highly mobile low-strength cohesive debris flows produce extensive deposits restricted to distal areas. These low-strength debris flows may contain clasts and travel long distances (D M-2 ), or result from more local flow transformation due to turbulence damping by cohesive mud (D M-1 ). Mapping of individual flow deposits (beds) emphasizes how a single event can contain several flow types, with transformations between flow types. Flow transformation may be from dilute to dense flow, as well as from dense to dilute flow. Flow state, deposit type and flow transformation are strongly dependent on the volume fraction of cohesive fine mud within a flow. Recent field observations show significant deviations from previous widely cited models, and many hypotheses linking flow type to deposit type are poorly tested. There is much still to learn about these remarkable flows.
    Print ISSN: 0037-0746
    Electronic ISSN: 1365-3091
    Topics: Geosciences
    Published by Wiley
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  • 9
    Publication Date: 2012-09-19
    Description: Active gas venting occurs on the uppermost continental slope off west Svalbard, close to and upslope from the present-day intersection of the base of methane hydrate stability (BMHS) with the seabed in about 400 m water depth in the inter-fan region between the Kongsfjorden and Isfjorden cross-shelf troughs. From an integrated analysis of high-resolution, two-dimensional, pre-stack migrated seismic reflection profiles and multibeam bathymetric data, we map out a bottom simulating reflector (BSR) in the inter-fan region and analyze the subsurface gas migration and accumulation. Gas seeps mostly occur in the zone from which the BMHS at the seabed has retreated over the recent past (1975–2008) as a consequence of a bottom water temperature rise of 1°C. The overall margin-parallel alignment of the gas seeps is not related to fault-controlled gas migration, as seismic evidence of faults is absent. There is no evidence for a BSR close to the gas flare region in the upper slope but numerous gas pockets exist directly below the predicted BMHS. While the contour following trend of the gas seeps could be a consequence of retreat of the landward limit of the BMHS and gas hydrate dissociation, the scattered distribution of seeps within the probable hydrate dissociation corridor and the occurrence of a cluster of seeps outside the predicted BMHS limit and near the shelf break indicate the role of lithological heterogeneity in focusing gas migration.
    Print ISSN: 0148-0227
    Topics: Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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  • 10
    Publication Date: 2011-07-22
    Description: The nature of active deformation in the Gulf of Cadiz is important for developing a better understanding of the interplate tectonics and for revealing the source of the 1755 Great Lisbon earthquake. New, high-resolution 3-D seismic data reveal a classic pull-apart basin that has formed on an east striking fault in the Southern Lobe of the Gulf of Cadiz accretionary wedge. Geometrical relationships between an array of faults and associated basins show evidence for both dextral and sinistral shear sense in the Southern Lobe. Strike-slip faulting within the lobe may provide a link between frontal accretion at the deformation front and extension and gravitational sliding processes occurring further upslope. Inception of the strike-slip faults appears to accommodate deformation driven by spatially variant accretion or gravitational spreading rates, or both. This implies that active deformation on strike-slip faults in the Southern Lobe is unrelated to the proposed modern inception of a transform plate boundary through the Gulf of Cadiz and underscores the importance of detailed bathymetric analysis in understanding tectonic processes.
    Electronic ISSN: 1525-2027
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Published by Wiley on behalf of American Geophysical Union (AGU).
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