KAr and RbSr ages of pegmatites in the south central Alps

Hanson, Gilbert N.; Tahlawi, M. R. El; Weber, W.

doi:10.1016/0012-821x(66)90037-9

Cited by 20 publications

(14 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…It is well known that K/Ar ages in muscovites are much more affected by heating processes than the Rb/Sr ones, and thus more easily resettled by thermal events. It is difficult, from the data up to now discussed, to determine the real age o~ emplacement of these pegmatites; in some cases (FEBnARA, 1973;HANSON, 1966) there is a complete agreement between the Rb/Sr and K/Ar data that can be interpreted not only as a complete Sr re-equilibration, but also as representative of the true age of the pegmatitic body. It is however evident, as pointed out by HANSON (1966); GRAU~BT & SOPT~AJANOVA (1972) that at that time the temperatures were high enough not only for the complete reset of the K/Ar clock but also for the re-equilibration of Sr among the different minerals of the pegmatites.…”

Section: Intrusive Hercynian Massivesmentioning

confidence: 92%

Radiometric age evidences of a Triassic Thermal Event in the Southern Alps

Ferrara¹,

Innocenti²

1974

Geol Rundsch

View full text Add to dashboard Cite

ZusammenfassungZahlreiche K/Ar-Altersbestimmungen deuten auf eine Aufheizung in den Siidalpen wiihrend der Oberen Trias. Biotite herzynischer periadriatischer Massive und Muskovite aus Pegmafiten geben verjiingte K/Ar-Alter, In den Pegmatiten fand auch eine Strontium-Isotopenhomogenisierung statt. Weitere Hinweise ffir eine obertriassisehe Aufheizung finden sieh im metamorphen Grundgebirge. Zahlreiehe Vorkommen effusiver und intrusiver alkaliseher Gesteine fallen in den gleichen Zeitraum. Diese Beobaehtungen werden als Ereignisse interpretiert, die der Expansion und der Ausbildung einer ozeanisehen Kruste in der alpinen Region wiihrend des Unteren Jura direkt vorausgingen. AbstractIn the Southern Alps several K/Ar age determinations point out the existence of a thermal event of Upper-Triassic age. Radiometric evidences concern overprinting on K/Ar ages of biotites belonging to hercynian periadriatic massives, and of muscovites of pegmatites in which also a Sr isotopic re-equilibration has taken place. Some evidences are also recognizable in ancient metam0rphie basement. In the same time an extensive extrusive and intensive magmatie activity of alkaline affinity occurred. These facts are interpreted as predrift events shortly preeeeding the set up of lower Jurassic oceanic conditions of alpine area.

show abstract

Section: Intrusive Hercynian Massivesmentioning

confidence: 92%

Radiometric age evidences of a Triassic Thermal Event in the Southern Alps

Ferrara¹,

Innocenti²

1974

Geol Rundsch

View full text Add to dashboard Cite

show abstract

“…Within the range there are two maxima at 222 + 4 my and at 263 + 12; the former is rather well defined, the latter not so well, as the standard deviation clearly shows. The older age is essentially in agreement with the sole previous determination (HANSON et al, 1966, sample P 31:239 + 12 my or, after recalculation with the new constants, 245 + 12 my). The only quartzo-feldspatic rock containing biotite (DAT-13) gives a young age of 229 my, although it comes from the >,intermediate pressure unit~,.…”

Section: Mineral Ages a Biotitesmentioning

confidence: 84%

“…The discussion will include all the samples, since all the results are completely compatible from any experimental viewpoint. All the data are given in Table 1, where the scanty previous determinations by HANSON et al (1966) are also given for sake of comparison, but recomputed with the new age constants. Individual ages are reported in the histogramme of Fig.…”

Section: Methodsmentioning

confidence: 99%

“…The available ages on muscovites are 17, including five of the pegmatites of the Piona swarm (HANSON et al, 1966). Their distribution is essentially bimodal, as the biotite ages were, but shifted toward lower values.…”

Section: B Muscovitesmentioning

confidence: 98%

“…c) A second, important metamorphic episode occurred during the main phase of the Hercynian orogenesis, and is indicated by the cooling age 239 + 12 my measured by the K-Ar method on the biotite of a garnet-staurolite schist at Corenno Plinio, only 1.5 km away from Sueglio (PuRDY & JXcER, 1976). Alternatively, it was suggested that this age was related to a thermal event, either the Permian volcanic activity (HANSON et al, 1966), or the remobilitization of crustal material shortly before the breakup of the Eurasian continental block into plates, with the formation of new oceanic basins (F~Rv, ARA & INNOCENt, 1974).…”

Section: Introductionmentioning

confidence: 98%

See 2 more Smart Citations

Pre-alpine and alpine evolution of the South-alpine basement of the Orobic Alps

Mottana¹,

Nicoletti

Petrucciani

et al. 1985

Geol Rundsch

View full text Add to dashboard Cite

Thermochronometry Across the Austroalpine‐Pennine Boundary, Central Alps, Switzerland: Orogen‐Perpendicular Normal Fault Slip on a Major “Overthrust” and Its Implications for Orogenesis

2018

View full text Add to dashboard Cite

Fifty‐one new and 309 published thermochronometric ages (nine systems with closure temperatures ranging from ~450 to 70°C) from the Graubünden region of the Central Alps demonstrate that a pronounced thermal mismatch between the Austroalpine allochthon (Alpine “orogenic lid”) and the Pennine zone persisted until at least 29 Ma and, allowably, until circa 18 Ma. The observed mismatch supports previous suggestions that the famous “overthrust” between the Austroalpine allochthon and the Pennine zone, historically regarded as primarily an Eocene top‐north thrust fault, is in fact primarily an Oligocene‐Miocene normal fault that has a minimum of 60 km of displacement with top‐south or top‐southeast sense of shear. Two hallmarks of Alpine geology, deposition of the foredeep Molasse and emplacement of the Helvetic nappes, appear to be coeval, peripheral manifestations of crustal thickening via the interposition of the Pennine zone as a northward intruding wedge between the Austroalpine “lid” and the European cratonic margin, with the Helvetic system (European margin) acting as the “floor” of the wedge. We presume the Penninic wedge is driven by the buoyant rise of subducted crust no longer able to remain attached to the descending slab. If so, emplacement of the Pennine wedge could have occurred mainly after Adria was juxtaposed against cratonic Europe.

show abstract

KAr and RbSr ages of pegmatites in the south central Alps

Cited by 20 publications

References 2 publications

Radiometric age evidences of a Triassic Thermal Event in the Southern Alps

Radiometric age evidences of a Triassic Thermal Event in the Southern Alps

Pre-alpine and alpine evolution of the South-alpine basement of the Orobic Alps

Thermochronometry Across the Austroalpine‐Pennine Boundary, Central Alps, Switzerland: Orogen‐Perpendicular Normal Fault Slip on a Major “Overthrust” and Its Implications for Orogenesis

Contact Info

Product

Resources

About