scholarly journals Geo-thermochronology of the Saint Antonin basin, south-eastern France

2018 ◽  
Vol 189 (3) ◽  
pp. 12 ◽  
Author(s):  
Sébastien Jourdan ◽  
Matthias Bernet ◽  
Elizabeth Hardwick ◽  
Jean-Louis Paquette ◽  
Pierre Tricart ◽  
...  
Keyword(s):  
Drainage Basin ◽  
Fission Track ◽  
Western Alps ◽  
Sediment Provenance ◽  
Maritime Alps ◽  
Compression Phase ◽  
South Eastern ◽  
Early Oligocene ◽  
Zircon Fission Track ◽  
Exhumation Rates

The clastic sedimentary formations of the Saint Antonin basin in the French Maritime Alps contain the record of the Early Oligocene erosional history of the Maures-Esterel massif, Sardinia and Corsica. Detrital apatite fission-track dating and zircon fission-track/U-Pb double dating of samples collected from the Saint Antonin basin confirm sediment provenance and allow obtaining first-order estimates of drainage basin maximum and long-term average exhumation rates. Whereas average exhumation rates were on the order of 0.1–0.2 km/Myr during the Early Oligocene, small parts of the Saint Antonin basin source areas may have experienced maximum exhumation rates on the order of 0.4–0.7 km/Myr. Although zircons and apatites with Early Oligocene fission-track cooling ages make up between 11–15% of the dated grains, a possible volcanic contribution is negligible, as only one single volcanic zircon grain was identified by fission-track/U-Pb double dating. Regional geodynamic processes with convergence in the Western Alps to the east and the end of the Pyreneo-Provençal compression phase by the early Oligocene controlled the differences in basin fill history and sediment provenance between the Saint Antonin basin and the largely contemporaneous Barrême basin in south-eastern France.

The Oligocene orogenic pulse in the southern Penninic arc (western Alps): structural, sedimentary and thermochronological constraints

2011 ◽  
Vol 182 (1) ◽  
pp. 25-36 ◽  
Author(s):  
Matthias Bernet ◽  
Pierre Tricart
Keyword(s):  
Western Alps ◽  
White Mica ◽  
Slowing Down ◽  
Early Oligocene ◽  
Climatic Control ◽  
Southern Branch ◽  
Lag Times ◽  
Exhumation Rates ◽  
High Topography

Abstract The Oligocene evolution of the southern branch of the western Alpine arc, more precisely the stack of metamorphic Briançonnais and Piedmont nappes composing the southern Penninic arc (SPA), are the focus of this study. We review published structural, sedimentological and thermochronological data in order to discuss exhumation of the SPA. At first, we compare bedrock zircon and apatite fission-track (FT) data from the SPA with detrital thermochronologic data (zircon FT, white mica 40Ar/39Ar) from Oligocene molasse deposits. Using improved stratigraphic ages for the Barrême basin, samples from the uppermost Rupelian “Conglomérat de Clumanc” and the Chattian “Molasse Rouge” provided zircon FT lag times of ~3.5 and 8 m.y., indicating source exhumation rates on the order of ~1.5 and ~0.75 km/m.y. respectively. These short lag times are consistent with lag times of 40Ar-39Ar ages of detrital white mica from the same formations in the same basin, and also from Oligocene molasse sediments in the Tertiary Piedmont basin. The sediment source for these grains as for the associated clasts of blueschist, is identified as the HP-LT metamorphic units of the SPA. The source cannot be the Ubaye-Embrunais nappes as classically considered, because these nappes do not bear the required metamorphic imprint. This interpretation is consistent with fast Oligocene cooling of the SPA, as attested by in situ zircon and apatite FT analyses. Such fast and relatively old cooling is a peculiarity of the southern branch of the western Alpine arc, when considering the entire arc. A second range of data concerns the structural building of the SPA. The initial stacking of metamorphic nappes in a poorly elevated accretionnary wedge was completed before the end of the Eocene. During the Early Oligocene collision, this wedge was severely refolded, acquiring its fan structure, as visible in cross section, and its curvature in map view. In such a context, we propose that fast exhumation and cooling of the SPA during the Oligocene resulted from active erosion of rapidly raised high topography. This is consistent with the sudden arrival of metamorphic Penninic clasts in the molasse basins along both flanks of the belt. Moreover, detrital and in situ thermochronological ages, suggest a strong slowing down of cooling and exhumation from the Miocene onwards, coinciding with brittle extension that dominates in the SPA during this long period. The brief Early Oligocene rise of a SPA cordillera, contrasts with the preceding and subsequent period of poor relief of the SPA. The mountainous character of the SPA today is not directly inherited from the Oligocene orogenic climax, as modern high relief and elevation are most likely related to rejuvenation under climatic control during the Quaternary.

scholarly journals Revealing exhumation of the central Alps during the Early Oligocene by detrital zircon U–Pb age and fission-track double dating in the Taveyannaz Formation

2020 ◽  
Vol 109 (7) ◽  
pp. 2425-2446
Author(s):  
Gang Lu ◽  
Maria Giuditta Fellin ◽  
Wilfried Winkler ◽  
Meinert Rahn ◽  
Marcel Guillong ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Fission Track ◽  
Foreland Basin ◽  
Late Eocene ◽  
Central Alps ◽  
Early Oligocene ◽  
Zircon Fission Track ◽  
Northern Alpine Foreland ◽  
Alpine Foreland ◽  
Alpine Foreland Basin

Abstract The late Eocene-to-early Oligocene Taveyannaz Formation is a turbidite series deposited in the Northern Alpine Foreland Basin (close to the Alpine orogenic front). Double dating of zircons with the fission-track and the U–Pb methods is applied on samples from the Taveyannaz Formation to reconstruct the exhumation history of the Central-Western Alps and to understand the syn-collisional magmatism along the Periadriatic lineament. Three samples from this unit show similar detrital zircon fission-track age populations that center at: 33–40 Ma (20%); 69–92 Ma (30–40%); and 138–239 Ma (40–50%). The youngest population contains both syn-volcanic and basement grains. Combined with zircon U–Pb data, it suggests that the basement rocks of Apulian-affinity nappes (Margna Sesia, Austroalpine) were the major sources of detritus, together with the Ivrea Zone and recycled Prealpine flysch, that contributed debris to the Northern Alpine Foreland Basin. Furthermore, the rocks of the Sesia–Lanzo Zone or of equivalent units exposed at that time presumably provided the youngest basement zircon fission-track ages to the basin. The Biella volcanic suite was the source of volcanogenic zircons. Oligocene sediment pathways from source to sink crossed further crystalline basement units and sedimentary covers before entering the basin from the southeast. The lag times of the youngest basement age populations (volcanic zircons excluded) are about 11 Myr. This constrains average moderate-to-high exhumation rate of 0.5–0.6 km/Myr in the pro-side of the orogenic wedge of the Central Alps during the late Eocene to early Oligocene.

La denudation tectonique de la zone ultradauphinoise et l'inversion du front brianconnais au sud-est du Pelvoux (Alpes occidentales); une dynamique miocene a actuelle

2001 ◽  
Vol 172 (1) ◽  
pp. 49-58 ◽  
Author(s):  
Pierre Tricart ◽  
Stephane Schwartz ◽  
Christian Sue ◽  
Gerard Poupeau ◽  
Jean-Marc Lardeaux
Keyword(s):  
Fission Track ◽  
Field Work ◽  
Western Alps ◽  
Late Eocene ◽  
Low Grade ◽  
Current Field ◽  
External Zone ◽  
Early Oligocene ◽  
Magmatic Intrusions

Abstract In the western Alps, to the southeast of the Pelvoux massif (Champsaur-Embrunais-Brianconnais-Queyras transect), the Brianconnais zone consists of the southern tip of the Zone Houillere and small nappes of Mesozoic sediments, emplaced during the Eocene in HP-LT metamorphic conditions. During the Oligocene this tectonic pile was thrusted onto a late Eocene to early Oligocene flexural basin, deformed in low grade metamorphic conditions and belonging to the Ultradauphine zone. This major thrust, called here CBF [Chevauchement Brianconnais Frontal: Tricart 1986] represents the boundary between the external and the internal zones of the western Alps. It contains thin tectonic lenses of Subbrianconnais origin, so that the Brianconnais Front and the Penninic Front almost merge. Late Alpine extension. - We have recently discovered that the CBF was subsequently reactivated as an extensional detachment. This major negative inversion is associated with widespread extension in the internal (Brianconnais and Piemont) zones, resulting in multiscale normal faulting. Current field work in the Queyras area shows that this brittle multitrend extension is a continuation of the ductile extension that accompanied the exhumation of blue-schist bearing metamorphic units. Along the same transect, the external (Ultradauphine) zone was not affected by late-Alpine extension. This is still the present situation: to the east of the aseismic Pelvoux massif, the CBF bounds the Brianconnais seismic arc, the activity of which may be the continuation of the late-Alpine extension. At the scale of the western Alpine arc, active extensional-transtensional tectonics dominate in the internal zones while compressional uplift affects the external zone. In this contrasted stress field, the thrust-fault zone between internal and external arcs plays a major role of decoupling that can be demonstrated in several sites between the area analysed here and the Central Alps, including along the Ecors profile. Contribution of thermochronology. - In this paper, we compare apatite fission track (FT) ages from both sides of the inverted CBF to the southeast of the Pelvoux massif. In the hangingwall of the CBF, two ages were obtained from magmatic intrusions within the Zone houillere, close to Briancon. They are compared to recently published ages from the Champsaur Sandstones unit in the footwall of the CBF, along the same transect.

Structural and thermochronological studies of the Almora klippe, Kumaun, NW India: implications for crustal thickening and exhumation of the NW Himalaya

2018 ◽  
Vol 481 (1) ◽  
pp. 81-110 ◽  
Author(s):  
M. K. Puniya ◽  
R. C. Patel ◽  
P. D. Pant
Keyword(s):  
Fission Track ◽  
Crustal Thickening ◽  
Indian Plate ◽  
Temperature Pattern ◽  
Thermal Profile ◽  
Nw Himalaya ◽  
Himalayan Orogeny ◽  
Zircon Fission Track ◽  
Ramgarh Thrust ◽  
Exhumation Rates

AbstractCrystalline klippen over the Lesser Himalayan Metasedimentary Sequence (LHMS) zone in the NW Himalaya have specific syn- and post-emplacement histories. These tectonics also provide a means to understand the driving factors responsible for the exhumation of the rocks of crystalline klippen during the Himalayan Orogeny. New meso- and microscale structural analyses, and thermochronological studies across the LHMS zone, Ramgarh Thrust (RT) sheet and Almora klippe in the eastern Kumaun region, NW Himalaya, indicate that the RT sheet and Almora klippe were a part of the Higher Himalayan Crystalline (HHC) of the Indian Plate which underwent at least one episode of pre-Himalayan deformation and polyepisodic Himalayan deformation in ductile and brittle–ductile regimes. The deformation temperature pattern within the Almora klippe records a normal thermal profile from its base to top but an inverted thermal profile from the base of Almora klippe down towards the LHMS zone. New fission-track data collected across the RT sheet and Almora klippe along Chalthi–Champawat–Pithoragarh traverse in the east Kumaun region document the exhumation of both units since Eocene times. Zircon fission-track (ZFT) ages from the Almora klippe range between 28.7 ± 2.4 and 17.6 ± 1.1 Ma, and from the RT sheet between 29.8 ± 1.6 and 22.6 ± 1.9 Ma; and the apatite fission-track (AFT) ages from the Almora klippe range between 15.1 ± 1.7 and 3.4 ± 0.5 Ma, and from the RT sheet between 8.7 ± 1.2 and 4.6 ± 0.6 Ma. The age pattern and diverse patterns of the exhumation rates reflect a clear tectonic signal in the RT sheet and the Almora klippe which acknowledge that the Cenozoic tectonics influenced the exhumation pattern in the Himalaya.

Downstream Changes of Alpine Zircon Fission-Track Ages in the Rhone and Rhine Rivers

2004 ◽  
Vol 74 (1) ◽  
pp. 82-94 ◽  
Author(s):  
M. Bernet ◽  
M. T. Brandon ◽  
J. I. Garver ◽  
B. Molitor
Keyword(s):  
Fission Track ◽  
Zircon Fission Track ◽  
Fission Track Ages

Falcatifolium (Podocarpaceae) macrofossils from paleogene sediments in south-eastern Australia: a reassessment

1998 ◽  
Vol 11 (6) ◽  
pp. 711 ◽  
Author(s):  
Robert S. Hill ◽  
Leonie J. Scriven
Keyword(s):  
Leaf Morphology ◽  
Middle Eocene ◽  
Late Eocene ◽  
South Eastern ◽  
Early Oligocene ◽  
Extant Species ◽  
Eastern Australia ◽  
South Eastern Australia

A re-investigation of macrofossils previously referred to the extantpodocarpaceous genus Falcatifolium Laubenfels shows thatno records can be sustained. Falcatifolium australisD.R.Greenwood from Middle Eocene sediments in Victoria bears littleresemblance to extant species in the genus and is transferred to the newfossil genus Sigmaphyllum R.S.Hill & L.J.Scriven.Specimens from Early Oligocene sediments in Tasmania previously assigned toFalcatifolium are described as a second species ofSigmaphyllum, S. tasmanensisR.S.Hill & L.J.Scriven, and specimens from mid to late Eocene sediments inTasmania previously assigned to Falcatifolium do notbelong to that genus, although their true generic affinities are uncertain.Dispersed cuticle specimens from Late Eocene–Oligocene sediments inSouth Australia referred to Falcatifolium are notreliable records of the genus and require further investigation. However,Dacrycarpus eocenica D.R.Greenwood, from Middle Eocenesediments in Victoria is transferred to Falcatifolium,and is similar to the extant species F. angustumLaubenfels, which has a leaf morphology unusual for the genus.Falcatifolium eocenica (D.R.Greenwood) R.S.Hill & L.J.Scriven is the only reliable record of the genus in the Australian fossilrecord to date.

Low-temperature thermal history of the Gilmore Dome area, Fairbanks Mining District, Alaska

1993 ◽  
Vol 30 (4) ◽  
pp. 764-768 ◽  
Author(s):  
John M. Murphy ◽  
Arne Bakke
Keyword(s):  
Gold Deposit ◽  
Fission Track ◽  
Hydrothermal Fluids ◽  
Mining District ◽  
Cooling Path ◽  
Alteration Assemblage ◽  
Zircon Fission Track ◽  
History Of ◽  
Maximum Temperatures ◽  
Fission Track Ages

Eight apatite and two zircon fission-track ages provide evidence of complex Tertiary thermal overprinting by hydrothermal fluids in the Gilmore Dome area. Five ages on apatite from the Fort Knox gold deposit average 41 Ma, one from the Stepovich prospect is 80 Ma, and two from Pedro Dome average 67 Ma. Elevations of these samples overlap but their ages do not, indicating that each area experienced a different thermal history.Ages of apatite from the Fort Knox gold deposit decrease with elevation from 42 to 36 Ma but have data trends indicative of complex cooling. Two ~51 Ma ages on zircon indicate that maximum temperatures approached or exceeded ~180 °C. An alteration assemblage of chalcedony + zeolite + calcite + clay in the deposit resulted from deposition by a paleo-hydrothermal system. The data suggest that the system followed a complex cooling path from > 180 to < 110 °C between 51 and 36 Ma, and that final cooling to below 60 °C occurred after ~25 Ma.The 80 Ma age from Stepovich prospect either resulted from cooling after intrusion of the underlying pluton (~90 Ma) or records postintrusion thermal overprinting sometime after ~50 Ma. The 67 Ma samples from Pedro Dome may also have experienced partial age reduction during later heating. The differences in the data from the different areas and the presence of a late alteration assemblage at Fort Knox suggest that the fluids responsible for heating were largely confined to the highly fractured and porous Fort Knox pluton.

Trace metal concentrations and OH defects in quartz from Amazon River sands & and perspectives for application to the marine record

2021 ◽  
Author(s):  
Dominik Jaeger ◽  
Roland Stalder ◽  
Cristiano Chiessi ◽  
André Sawakuchi ◽  
Michael Strasser
Keyword(s):  
Trace Metal ◽  
Drainage Basin ◽  
River Sediments ◽  
Sediment Provenance ◽  
Future Application ◽  
Amazon River ◽  
Analysis Tool ◽  
Metal Concentrations ◽  
Oh Defects ◽  
Quartz Grains

&lt;p&gt;Trace metal concentrations and associated hydrous lattice point defects (OH defects) in quartz can help reveal its host rock&amp;#8217;s crystallization history and are easily quantified using electron microprobe and infrared spectroscopy, respectively. These chemical impurities are preserved throughout the sedimentary cycle and thus lend themselves as tracers for sediment provenance analyses, particularly in settings where &amp;#8220;traditional&amp;#8221; provenance tools, e.g., thermochronology and heavy mineral analysis, are difficult due to factors like low mineral fertility and aggressive tropical weathering.&lt;/p&gt;&lt;p&gt;In this study, we apply this provenance analysis tool to detrital, sand-sized quartz grains from the Amazon River and its major tributaries, draining the Andean orogen as well as the Guiana- and Central Brazil Shields. Trace metal and OH defect concentrations from individual catchments are spread out over wide and mutually overlapping ranges of values. This means that each individual quartz grain cannot be unequivocally attributed to one catchment. However, evaluation of a statistically sound number of grains reveals that Andean quartz is, on average, richer in the trace metal aluminum (and Al-related OH defects) than quartz derived from one of the shield sources.&lt;/p&gt;&lt;p&gt;We evaluate our findings in the context of previous provenance studies on Amazon River sediments and discuss a potential future application of analyzing trace metals and OH defects in quartz in the offshore sediment record. Any past, major rearrangements in the Amazon watershed affecting the ratio of Andean vs. Shield-derived quartz grains should be detectable and our approach may therefore contribute to the reconstruction of Amazon drainage basin evolution.&lt;/p&gt;

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