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Topic: Hettangian

	Base of Sinemurian Stratotype
		The Blue Lias typically shows sedimentary cycles which, from the base upwards, comprise: bituminous shale — marl — limestone — marl.
		The boundary level corresponds with the striking change in the ammonite fauna from the genus Schlotheimia (mainly Schlotheimia pseudomoreana) in the latest Hettangian to the genera Vermiceras and Metophioceras in the earliest Sinemurian.
		substriata is characteristic of the latest Hettangian and the consistent appearance of Planularia inaequistriata and the Frondicularia terquemi plexus group is characteristic of the basal Sinemurian.
	www.stratigraphy.org /sinemurian.htm (360 words)

	Spartanburg SC \| GoUpstate.com \| Spartanburg Herald-Journal
		Stretching for around 14 miles just outside Cardiff, the remarkable strata of the cliffs, situated on the Bristol Channel are a mixture of carboniferous sandstone/limestone, shale and liassic limestone, created during a geological upheaval known as the variscan orogeny.
		Biostratigraphically, the first appearance of psiloceratid ammonites has been used; but this depends on relatively complete ammonite faunas being present, a problem that makes correlation between sections in different parts of the world difficult.
		The Hettangian saw the already existing Rhaetian ichthyosaurs and plesiosaurs continuing to flourish, while at the same time a number of new types of these marine reptiles appeared, such as Ichthyosaurus and Temnodontosaurus among the ichthyosaurs, and Eurycleidus, Macroplata, and Rhomaleosaurus among the plesiosaurs (all Rhomaleosauridae, although as currently defined this group is probably paraphyletic).
	www.goupstate.com /apps/pbcs.dll/section?category=NEWS&template=wiki&text=Early_Jurassic (0 words)

	alb21-3
		The work of the TJBWG will be reported in more detail as progress is made towards the selection of a GSSP for the base of the Hettangian Stage, marking the base of the Jurassic and, inter alia, the top of the Trias.
		Important discoveries, which are very relevant to discussions on the definition of the Triassic/Jurassic (T/J) boundary, have recently been made during the study of the lowest ammonite faunas in the Lias Group in the UK (Bloos and Page 1997; Page and Bloos 1998).
		Copestake and Partington - Stratigraphic sequences in the Jurassic-lowermost Cretaceous (Hettangian to Ryazanian) of the North Sea Basin and adjacent areas of north west Europe.
	www.biologie.uni-hamburg.de /b-online/kerp/Albart11.htm (0 words)

	Department of Earth Sciences \| Abstract
		K-Ar isochron dates of 193 ± 2, 189 ± 3, and 191 ± 2 Ma are reported for the Shelburne dike of Nova Scotia, the Avalon dike of Newfoundland, and the Caraquet dike of New Brunswick, respectively.
		The virtual paleopoles from Hettangian flows and dikes of Atlantic Canada lie on average 11 north of the virtual paleopoles from Hettangian flows of the northeastern United States.
		This discrepancy is likely due to insufficient averaging out of paleosecular variation and demonstrates that caution is needed in paleomagnetically correlating among the Early Jurassic flows and intrusions of eastern North America.
	www.mun.ca /earthsciences/Hodych/Hodych_Abstract_10.php (0 words)

	SEDIMENTARY FEATURES AND PALYNOFACIES OF THE TRIASSIC/JURASSIC BOUNDARY INTERVAL
		The next significant facies change in the Early Hettangian is marked by the appearance of redeposited oncoid—grapestone beds, indicating the end of the Rhaetian to earliest Hettangian sequence.
		This microplankton assemblage is characteristic of a permanently stratified basin.
		Palynofacies of the Lower Hettangian is dominated by degraded organic matter, small equidimensional phytoclasts and foraminiferal test linings, pointing to a distal basinal setting.
	gsa.confex.com /gsa/2006AM/finalprogram/abstract_112526.htm (0 words)

	Amazon.com: Hettangian
		Early Hettangian ammonites and radiolarians from the Queen Charlotte Islands, British Columbia and their bearing on the definition of the Triassic-Jurassic...
		Hettangian through Aalenian (Jurassic) guide fossils and biostratigraphy, northern Yukon and adjacent Northwest Territories (Bulletin / Geological Survey of Canada) by T. P Poulton (Unknown Binding - 1991)
		Hettangian Ammonite faunas of the Taseko Lakes area, British Columbia (Geological Survey of Canada.
	www.amazon.com /s?ie=UTF8&keywords=Hettangian&index=blended&page=1 (0 words)

	McHone&Puffer SignificancePaper
		The original extent of Hettangian Pangaean rift basalts is estimated from maps of feeder dikes and Mesozoic basins that contain remnants of the basalts.
		Dikes and basalts across the initial Pangaean rift zone are correlated by radiometric dates near 200 Ma, stratigraphy of associated basin sediments, and chemical characteristics.
		The total thickness of Hettangian basalts varies widely among basins, but 200 meters is a conservative estimate for an average thickness over the rift terrane and adjacent continental dike swarms.
	www.auburn.edu /academic/science_math/res_area/geology/camp/McHone_Puffer.html (0 words)

	Hettangian, Sinemurian and Pliensbachian - GCR block
		The GCR sites selected for this GCR Block represent the British geological record of Earth history from about 200 to 184 million years ago (Ma).
		The Hettangian (200—197 Ma), Sinemurian (197—192 Ma) and Pliensbachian (192—184 Ma) strata are included in one GCR Block together because they are geologically commonly closely associated —over much of southern England they approximately equate with the lithostratigraphically defined terms, ‘Lower Lias’ and ‘Middle Lias’, (the Toarcian Stage being equated to the ‘Upper Lias’).
		With few exceptions these deposits are fully marine and mark a striking contrast with the predominantly terrestrial deposits of the preceding Triassic System.
	www.jncc.gov.uk /earthheritage/gcrdb/GCRblock.asp?block=36 (0 words)

	Palaeos Mesozoic: Triassic: Rhaetian
		The Rhaetian Age succeeds the Norian Age and is followed by the Hettangian (earliest Jurassic).
		But this is made less likely by the fact that the typically Late Triassic Riojasuchus (an ornithosuchid) is found in association with Hemiprotosuchus (a protosuchid) [Bonaparte 1970].
		The common large Norian temnospondyl Cyclotosaurus disappears from central north Pangea in the Rhaetian, although the plagiosaurs continue; in fact they are more successful than ever, and are represented by the advanced genus Gerrothorax.
	www.palaeos.com /Mesozoic/Triassic/Rhaetian.html (3843 words)

	Organic Geochemistry of the Paris Basin
		These results as a whole show that the source rocks for the great majority of the Mesozoic oils are situated in the Lias, ranging from the Toarcian to the Hettangian, and that the zones having the best petroleum potential in the Basin are located in areas of strong subsidence in Lias times.
		The detailed examination of the hydrocarbons and biomarkers did not distinguish different oils from each other, no matter what depth they came from, nor could these oils be attributed to a specific origin in the different levels of the Lias.
		With regard to these oils, their main migration paths were probably the faults that cut through the Triassic and the bottom of the Lias, which must have played an important role during the Tertiary (distensional faults).
	www.editionstechnip.com /sources/Liste_IfpFiche.asp?Cle=42030271&Annee=1987 (385 words)

	Jurassic Summary
		The earliest epoch, the Lias Epoch, ranges from the start of the Jurassic Period to approximately 180 mya.
		The Lias Epoch is further subdivided into (from earliest to most recent) Hettangian, Sinemurian, Pliensbachian, and Toarcian stages.
		The middle epoch, the Dogger Epoch, ranges from 180 mya to 159 mya and is further subdivided into (from earliest to most recent) Aalenian, Bajocian, Bathonian, and Callovian stages.
	www.bookrags.com /Jurassic (0 words)

	Udalia
		Original stratigraphic range:Pantanellium browni Zone to Canutus rockfishensis - Wrangellium thurstonense Zone, middle/late Hettangian - late Sinemurian, Early Jurassic, Mesozoic.
		Biochronology and paleontology of Lower Jurassic (Hettangian and Sinemurian) radiolarians, Queen Charlotte Islands, British Columbia.
		Geological Survey of Canada Bulletin 496 : 1-162.
	www.mnhn.fr /mnhn/geo/radworld/genspumellaria/Udalia.html (0 words)

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