scholarly journals Discovery of a Powerful, Transient, Explosive Thermal Event at Marduk Fluctus, Io, in Galileo NIMS Data

2018 ◽  
Vol 45 (7) ◽  
pp. 2926-2933 ◽  
Author(s):  
A. G. Davies ◽  
R. L. Davies ◽  
G. J. Veeder ◽  
K. Kleer ◽  
I. Pater ◽  
...  
Keyword(s):  
Thermal Event

Problème de la limite Précambrien–Cambrien: étude radiochronologique par la méthode U–Pb sur zircons du volcan du Jbel Boho (Anti-Atlas marocain)

1977 ◽  
Vol 14 (12) ◽  
pp. 2771-2777 ◽  
Author(s):  
J. Ducrot ◽  
J. R. Lancelot
Keyword(s):  
Volcanic Rocks ◽  
Lower Paleozoic ◽  
Thermal Event

A 534 ± 10 Ma age has been obtained on zircons from Jbel Boho volcano by the U–Pb method; previous assumptions of older ages for the Anti-Atlas Infracambrien (Morocco) cannot be maintained. This formation belongs to the lower Paleozoic. A slight thermal event has affected the volcanic rocks during Variscan (or Hercynian) times and induced opening of the K–Ar and Rb–Sr systems; but the U–Pb system of the zircons has not been affected. These U–Pb data are further reasons to raise the Precambrian – Cambrian boundary to an age of 550–560 Ma.

scholarly journals Thermal Event Recognition Applied to Protection of Tokamak Plasma-Facing Components

2010 ◽  
Vol 59 (5) ◽  
pp. 1182-1191 ◽  
Author(s):  
Vincent Martin ◽  
Jean-Marcel Travere ◽  
François Bremond ◽  
Victor Moncada ◽  
Gwenaël Dunand
Keyword(s):  
Event Recognition ◽  
Tokamak Plasma ◽  
Thermal Event ◽  
Plasma Facing Components

Chapter 14 Cambrian-Ordovician history

1997 ◽  
Vol 17 (1) ◽  
pp. 257-271 ◽  
Author(s):  
W. Brian Harland
Keyword(s):  
Late Ordovician ◽  
Early Cambrian ◽  
The South ◽  
Thermal Event ◽  
Early Ordovician

Cambrian-Ordovician history is well documented in Svalbard with late Early Cambrian faunas and a range of Ordovician faunas to provide a basis for correlation. Not so extensive as Vendian, the rocks crop out in four areas: (i) only slightly deformed strata in the youngest Hecla Hoek (Oslobreen) Group in northeastern Svalbard yield especially rich Early to Mid-Ordovician faunas, (ii) The Hornsundian Geosyncline in south Spitsbergen with more variable facies and tectonic complications also exhibits Early Cambrian and Canadian strata, (iii) The Bjornoya succession reveals a marked hiatus between Vendian and Early and Mid-Ordovician strata, (iv) In western Svalbard the lack of Cambrian and Early Ordovician strata marks a distinct Mid Ordovician tectono-thermal event to be followed by ?Late Ordovician and Early Silurian strata. Indeed the above four areas correspond to distinct terranes which, having different affinities especially with areas in Greenland, give evidence of relatively distant areas and environments of formation. Evidence of Cambro-Ordovician volcanism is not recorded.Figure 14.1 lists the successions in the four areas mentioned according to the classification of rock units as abstracted from chapters 6, 7, 8, 9, 10 and 11, where their regional settings may be found. The outcrops are plotted on Fig. 14.2. The northeastern Svalbard strata are separated by Hinlopenstretet. This waterway divides Ny Friesland and Olav V Land in Spitsbergen from northwestern Nordaustlandet and occupies a syncline, but the successions although differently named are essentially continuous. In southern Spitsbergen the fjord Hornsund separates the successions to the south in Sorkapp Land

scholarly journals Early and Middle Wisconsinan Environments of Eastern Beringia: Stratigraphic and Paleoecological Implications of the Old Crow Tephra

2007 ◽  
Vol 39 (3) ◽  
pp. 275-290 ◽  
Author(s):  
Charles E. Schweger ◽  
John V. Matthews
Keyword(s):  
Permafrost Degradation ◽  
Land Bridge ◽  
Radiocarbon Dates ◽  
Thermal Event ◽  
Climate Fluctuations ◽  
Climatic Oscillations ◽  
Tundra Vegetation ◽  
Stage 4 ◽  
Shrub Tundra ◽  
Late Wisconsinan

ABSTRACTThe widespread Beringian Old Crow tephra occurs in Imuruk Lake (Alaska) core V, above the Blake paleomagnetic event and below Radiocarbon dates, which provide an extrapolated tephra age between 87 000 - 105 000 BP. Exposure KY-11 (Alaska), where the tephra occurs in a dated lacustrine sequence, provides corroboration. Fossil pollen records show that O.C.T. was deposited across northern Beringia on birch-shrub tundra vegetation during an interval of colder climate. A series of climatic oscillations followed tephra deposition. A prolonged period of cold-arid climate ( = marine isotope Stage 4) preceded an interval of warmer than present climate starting ca. 60 000 BP (beginning Stage 3). During this interval, designated the Koy-Yukon thermal event, an exposed Bering land bridge promoted an interglacial type climate that led to significant biotic changes and permafrost degradation. O.C.T. occurs on drift of the Mirror Creek Glaciation which is equivalent to other presumed Early Wisconsinan glaciations in Alaska and Yukon. These glaciations could not have occurred later than marine Stage 5. Stage 4 was fully as cold as Stage 2 (Late Wisconsinan), yet seems not to have been a time of extensive glaciation. The Middle Wisconsinan, 30 000 to more than 80 000 BP, was a nonglacial interval with several climate fluctuations, one of which, the Koy-Yukon thermal event, was warmer than at present.

Application of Apatite Fission-track Dating to the Study of Porphyry Type Mineral Deposits

1973 ◽  
Vol 10 (6) ◽  
pp. 846-851
Author(s):  
Peter A. Christopher
Keyword(s):  
British Columbia ◽  
Fission Track ◽  
Yukon Territory ◽  
Mineral Deposits ◽  
Fission Track Dating ◽  
Apatite Fission Track ◽  
Mountain Area ◽  
Thermal Event ◽  
Fission Track Ages ◽  
Apatite Fission Track Dating

Apatite fission-track ages for weakly altered rocks from the Syenite Range and Burwash Landing area of the Yukon Territory, and Cassiar area of British Columbia are shown to be consistent and generally concordant with K–Ar ages obtained on biotite from the same samples. More intensely altered rocks from Granisle Mine and the Copper Mountain area of British Columbia have discordant ages, due in part to alteration of apatite grains and, for samples from the Copper Mountain intrusions, to a Cretaceous (?) thermal event.

40Ar/39Ar Incremental Release Ages of Biotite and Hornblende from Pre-Kenoran Gneisses between the Matagami-Chibougamau and Frotet-Troilus Greenstone Belts, Quebec

1974 ◽  
Vol 11 (11) ◽  
pp. 1586-1593 ◽  
Author(s):  
R. D. Dallmeyer
Keyword(s):  
High Temperature ◽  
Tectonic Evolution ◽  
Superior Province ◽  
High Grade ◽  
Continuous Increase ◽  
Thermal Event ◽  
Greenstone Belts ◽  
Orogenic Belts ◽  
Gas Fractions

Biotite and hornblende from high-grade, granitic gneisses exposed between the Matagami-Chibougamau and Frotet-Troilus greenstone belts in Quebec have been affected by Kenoran metamorphism. Biotites record total gas 40Ar/39Ar ages of 2308 ± 30 m.y. and 2338 ± 30 m.y. Incrementally released gas fractions yield similar plateau ages, suggesting that the biotites have been totally degassed as a result of the thermal event. The ages are interpreted as reflecting the time of post-metamorphic cooling when radiogenic 40Ar began to be retained within biotite. Hornblendes record total gas 40Ar/39Ar ages of 2517 ± 40 m.y. and 2610 ± 40 m.y. Incrementally released gas fractions show a wide deviation from the total gas ages, with a continuous increase in age from low to high temperature release fractions. This lack of correlation suggests that the hornblendes have been only partially degassed by Kenoran metamorphism. However, lack of a high-temperature release plateau indicates that original meramorphic crystallization was older than the ages recorded by the highest temperature release fractions (2599 ± 40 and 2801 ± 40 m.y.). Recognition of an older sialic terrain between these greenstone belts supports recent models proposed for the tectonic evolution of the supracrustal orogenic belts in the Superior Province.

K–Ar and Fission Track Geochronometry of an Eocene Thermal Event in the Kettle River (West Half) Map Area, Southern British Columbia

1975 ◽  
Vol 12 (5) ◽  
pp. 836-843 ◽  
Author(s):  
G. A. Medford
Keyword(s):  
British Columbia ◽  
Abrupt Change ◽  
Fission Track ◽  
Apatite Fission Track ◽  
Thermal Event ◽  
South Central ◽  
Early Tertiary ◽  
Okanagan Valley

The Okanagan and Similkameen plutonic complexes west of the Okanagan Valley of south-central British Columbia yield K–Ar dates that range from 185 to 133 m.y. East of the Okanagan Valley Shuswap gneisses into which the plutonics intrude, and which may be as old as pre-midCarboniferous in age yield K–Ar dates between 59.9 and 47.4 m.y. This abrupt change, which approximately coincides with the Okanagan Valley, is a consequence of an intense thermal event in the early Tertiary which has reset K–Ar dates in the gneisses at shallow depths. Comparison of K–Ar, sphene and apatite fission track dates demonstrates that the heating affected the plutons west of the Okanagan Valley and that cooling of the Shuswap gneisses occurred at a rate in excess of 25 °C. per million years. The scatter observed in the older K–Ar dates of the plutonic complexes could be caused by post-emplacement heating with variable partial argon loss rather than by separate magmatic events. Thus, only the oldesl K–Ar dates obtained from the plutons may be significant as minimum ages for emplacement.

Discrepancies between different organic maturity indicators in a coal series affected by an abnormal thermal event (Viséan, Niger)

1993 ◽  
Vol 106 (3-4) ◽  
pp. 397-413 ◽  
Author(s):  
M. Harouna ◽  
J.R. Disnar ◽  
L. Martinez ◽  
J. Trichet
Keyword(s):  
Thermal Event

A model for the origin of the Lac St. Jean anorthosite massif

1976 ◽  
Vol 13 (2) ◽  
pp. 389-399 ◽  
Author(s):  
R. A. Frith ◽  
K. L. Currie
Keyword(s):  
Experimental Data ◽  
Partial Melting ◽  
Metamorphic Rocks ◽  
High Grade ◽  
Calc Alkaline ◽  
Grenville Province ◽  
Thermal Event ◽  
Anorthosite Massif ◽  
Mineral Assemblages ◽  
Potassic Rocks

An ancient tonalitic complex becomes migmatitic around the Lac St. Jean massif, ultimately losing its identity in the high grade metamorphic rocks surrounding the anorthosite. Field relations suggest extreme metamorphism and anatexis of tonalitic rocks. Experimental data show that extensive partial melting of the tonalite leaves an anorthositic residue. The same process operating on more potassic rocks would leave monzonitic or quartz syenitic residues. Synthesis of experimental data suggests that the process could operate at pressures of 5–8 kbar and temperatures of 800–1000 °C, which are compatible with mineral assemblages around the anorthosite massif. Slightly higher temperatures at the end of the process could generate magmatic anorthosite.Application of the model to the Grenville province as a whole predicts generation of anorthosite during a long-lived thermal event of unusual intensity. Residual anorthosite would occur as a substratum in the crust, overlain by high-grade metamorphic rocks intruded by anorthosite and syenitic rocks, while higher levels in the crust would display abundant calc-alkaline plutons and extrusives.

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