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

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.

scholarly journals Effects of fluid flow, cooling and deformation as recorded by 40Ar/39Ar, Rb–Sr and zircon fission track ages in very low- to low-grade metamorphic rocks in Avalonian SE Cape Breton Island (Nova Scotia, Canada)

2014 ◽  
Vol 152 (5) ◽  
pp. 767-787 ◽  
Author(s):  
ARNE P. WILLNER ◽  
SANDRA M. BARR ◽  
JOHANNES GLODNY ◽  
HANS-JOACHIM MASSONNE ◽  
MASAFUMI SUDO ◽  
...  
Keyword(s):  
Nova Scotia ◽  
Fission Track ◽  
White Mica ◽  
Low Grade ◽  
Cape Breton Island ◽  
Cape Breton ◽  
Zircon Fission Track ◽  
Meguma Terrane ◽  
Fission Track Ages ◽  
Oriented Parallel

Abstract40Ar/39Ar in situ UV laser ablation of white mica, Rb–Sr mineral isochrons and zircon fission track dating were applied to determine ages of very low- to low-grade metamorphic processes at 3.5±0.4 kbar, 280±30°C in the Avalonian Mira terrane of SE Cape Breton Island (Nova Scotia). The Mira terrane comprises Neoproterozoic volcanic-arc rocks overlain by Cambrian sedimentary rocks. Crystallization of metamorphic white mica was dated in six metavolcanic samples by 40Ar/39Ar spot age peaks between 396±3 and 363±14 Ma. Rb–Sr systematics of minerals and mineral aggregates yielded two isochrons at 389±7 Ma and 365±8 Ma, corroborating equilibrium conditions during very low- to low-grade metamorphism. The dated white mica is oriented parallel to foliations produced by sinistral strike-slip faulting and/or folding related to the Middle–Late Devonian transpressive assembly of Avalonian terranes during convergence and emplacement of the neighbouring Meguma terrane. Exhumation occurred earlier in the NW Mira terrane than in the SE. Transpression was related to the closure of the Rheic Ocean between Gondwana and Laurussia by NW-directed convergence. The 40Ar/39Ar spot age spectra also display relict age peaks at 477–465 Ma, 439 Ma and 420–428 Ma attributed to deformation and fluid access, possibly related to the collision of Avalonia with composite Laurentia or to earlier Ordovician–Silurian rifting. Fission track ages of zircon from Mira terrane samples range between 242±18 and 225±21 Ma and reflect late Palaeozoic reburial and reheating close to previous peak metamorphic temperatures under fluid-absent conditions during rifting prior to opening of the Central Atlantic Ocean.

scholarly journals Zircon (U-Th)/He Closure Temperature Lower than Apatite Ther-Mochronometric Systems: Reconciliation of a Paradox

2021 ◽  
Author(s):  
Benjamin Gilles Gérard ◽  
Xavier Robert ◽  
Cécile Gautheron ◽  
Djordje Grujic ◽  
Laurence Audin ◽  
...  
Keyword(s):  
Low Dose ◽  
Fission Track ◽  
Damage Model ◽  
Closure Temperature ◽  
Machu Picchu ◽  
Zircon Fission Track ◽  
Dose Ranging ◽  
Fission Track Ages ◽  
The One ◽  
Very High

We present here seven new zircon (U-Th)/He (ZHe) ages and three new zircon fission track ages (ZFT) analyzed from an age-elevation profile (Machu Picchu, Peru). ZFT data present older ages in comparison with the other thermochronological data, whereas the ZHe data interestingly present similar ages than the ones obtained with apatite (U-Th)/He (AHe). It has been proposed that He retention in zircon is linked to the damage dose, with an evolution of the closure-temperature from low values associated to low &alpha;-dose (&lt;1016 &alpha;/g), subsequently increasing before decreasing again at very high &alpha;-dose (&gt;1018 &alpha; /g). Studies have been focused on the He diffusion behavior at high &alpha;-dose, but little is known at low dose. We propose that the ZHe closure temperature at &alpha;-dose ranging from 0.6&times;1015 to 4&times;1016 &alpha;/g is in the range of ~60-80&deg;C. This value is lower than the one proposed in the current damage model ZRDAAM and demonstrates that the ZHe and AHe methods could have similar closure temperatures at low &alpha;-dose (i.e. similar ages). These new data strengthen our previous geological conclusions and even highlight an about twice more important cooling rate than the one deduced from AHe and apatite fission-track data alone registered at Machu Picchu.

scholarly journals Two pulse intrusive events of the Pliocene Tanigawa-dake granites revealed from zircon U–Pb dating

2021 ◽  
Vol 73 (1) ◽  
Author(s):  
Saki Minami ◽  
Mitsuhiro Nagata ◽  
Shigeru Sueoka ◽  
Shoma Fukuda ◽  
Yuya Kajita ◽  
...  
Keyword(s):  
Fission Track ◽  
Closure Temperature ◽  
Error Range ◽  
Zircon Fission Track ◽  
Northeast Japan Arc ◽  
Fission Track Ages

AbstractWe performed zircon U–Pb dating on the Pliocene Tanigawa-dake granites (Makihata and Tanigawa bodies) and the Cretaceous Minakami quartzdiorite, Northeast Japan Arc. Concordia ages were estimated to be 3.95 ± 0.11 Ma (± 2 sigma) for the Makihata body, 3.18 ± 0.13 Ma and 3.32 ± 0.15 Ma for the Tanigawa body, and 109.4 ± 2.2 Ma for the Minakami quartzdiorite. The Minakami quartzdiorite is possibly correlated to the bedrock in the Ashio belt because the age of the Minakami quartzdiorite is consistent with the zircon U–Pb ages of the earliest Tadamigawa granites (107–62 Ma) which are distributed to the northeast of the Tanigawa-dake region and belong to the Ashio belt. All the zircon U–Pb ages of the Tanigawa-dake granites are older than the previously reported cooling ages, i.e., K–Ar ages and zircon fission-track ages, being consistent with their difference in closure temperature. On the basis of these results, we concluded that the intrusive ages of the Tanigawa-dake granites are ~ 4–3 Ma, which are among the youngest exposed plutons on Earth. The U–Pb ages of the Makihata body and the Tanigawa body are different significantly in the 2 sigma error range. Thus, the Tanigawa body intruded later than the Makihata body by ~ 0.7 Myr. Graphical Abstract

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