The effect of α-damage of the fission-track annealing in zircon

Kasuya, Masao; Naeser, CharlesW.

doi:10.1016/1359-0189(90)90087-e

Cited by 17 publications

(24 citation statements)

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“…This situation occurs when already cold rock (i.e., quartzites at high levels in the crust) with zircon grains of differing radiation damage are heated. In this case, LRZs anneal at lower temperatures than the less damaged, more retentive grains (Kasuya and Naeser 1988;Brandon et al 1998). The LRZ grains could have been annealed at temperatures of ca.…”

Section: Discussionmentioning

confidence: 99%

“…A number of studies suggest that the thermal stability of FTs decreases with increasing a damage, and these studies give a slightly different result for the bounds of the zPAZ (Kasuya and Naeser 1988;Rahn et al 2004). Studies on reset, radiationdamaged zircons in heated strata of the Olympic Peninsula (Washington) indicate that the upper and lower bounds for the zPAZ are closer to 180Њ-240ЊC for 10-m.yr.…”

Section: Low-temperature Thermochronologymentioning

confidence: 99%

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Implications for Timing of Andean Uplift from Thermal Resetting of Radiation‐Damaged Zircon in the Cordillera Huayhuash, Northern Peru

Garver

Reiners

Walker

et al. 2005

The Journal of Geology

124

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A B S T R A C TThe Cordillera Huayhuash is a north-south-oriented range along the drainage divide of the northern Peruvian Andes. The range has high topography with peaks in excess of 5500 m and the second-highest peak in Peru, Nevados Yerupaja (6617 m). Bedrock is dominated by folded Mesozoic miogeoclinal rocks unconformably overlain by mid-Tertiary volcanics intruded by Late Tertiary granitic rocks and silicic dikes. Zircon fission track (ZFT) and (U-Th)/He (ZHe) dating of zircons along a west-east transect elucidates the thermal evolution of exhumed and uplifted rocks. The stability of fission tracks in zircons is a function of single-grain radiation damage. In samples with grain-to-grain variability in radiation damage, resetting results in variable resetting and multiple age populations. Low retentive zircons (LRZs), which have a partly disordered crystalline structure, have significant radiation damage and a low temperature of annealing (ca. 180Њ-200ЊC). High retentive zircons (HRZs), which are nearly crystalline, fully anneal at temperatures in excess of ca. 280Њ-300ЊC. Partly reset samples are those where LRZs are reset and HRZs are not reset, and therefore the cooling age is not concordant, but the young population of grain ages records the youngest thermal event. Full resetting of both LRZs and HRZs results in cooling ages that are concordant or nearly so. Lower Cretaceous quartzites show ZFT ages with a wide range of cooling ages, but most have LRZ reset ages at ca. 27 and 63 Ma. The ZFT ages from three quartzites and two granites from the core of the range yielded a single mean reset age of Ma. The ZHe ages from four samples in these rocks ranged from 10 to 7 Ma, with older ages away 11.4 ‫ע‬ 1 from the high topography. Together, the ZFT and ZHe cooling ages near the core of the range indicate moderate to rapid postintrusive cooling in the Miocene and a high Miocene geothermal gradient (ca. 40Њ-50ЊC/km). This widespread cooling age represents a falling geotherm, not a period of significant exhumation. Estimations of the thickness of preexhumation cover rock suggest that nearly 5 km of unroofing has occurred since the eruption of the Puscanturpa Formation (Huayllay Formation) at ca. 6.2 Ma. Exhumation was driven by valley incision initiated by uplift of this part of the Andes between 5 and 6 Ma. The high topography may have been formed by isostatic response to canyon incision. Therefore, the thermochronologic record of uplift and canyon incision is not yet apparent in the lowtemperature thermochronology (for zircons) of these rocks.

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Section: Discussionmentioning

confidence: 99%

Section: Low-temperature Thermochronologymentioning

confidence: 99%

Implications for Timing of Andean Uplift from Thermal Resetting of Radiation‐Damaged Zircon in the Cordillera Huayhuash, Northern Peru

Garver

Reiners

Walker

et al. 2005

The Journal of Geology

124

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“…The Paleozoic age of the protoliths, in relation to the influence of α damage in zircons [cf. Kasuya and Neaser , 1988], suggests instead T c ZFT values of about 240°C, according to Brandon et al [1998].…”

Section: Discussionmentioning

confidence: 99%

Miocene to Present differential exhumation in the Western Alps: Insights from fission track thermochronology

et al. 2005

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Analysis of cooling age patterns yielded by low-temperature thermochronometers provides key information about the role played by tectonic discontinuities during the late stages of exhumation of metamorphic belts. In the Western Alps, fission track data published so far are heterogeneously scattered and concentrated in few structural domains, preventing analyses at the scale of the whole belt. The new apatite fission track data reported in this work, obtained with the external detector method as well as the population method in very low U content samples, fill this gap. They constrain the postmetamorphic evolution of the Western Alps along two transects from the foreland to the retroforeland, unraveling the effective role played by some major faults during the exhumation of the belt at shallow crustal levels. A clear regional pattern, characterized by decreasing ages moving from the axial sector to the European external sector of the belt and by an along-strike gradient with increasing ages from north to south, has been unraveled. Evident breaks in this age pattern have been detected in correspondence of faults that are near-parallel to the trend of the belt, pointing to the occurrence of active tectonics during and after exhumation. The most apparent breaks have been observed in the axial sector of the belt, where the postmetamorphic deformation would have been negligible according to classic tectonic models. Faults located in the axial sector split the belt into two major blocks (eastern and western). Since the Miocene, the western block experienced higher exhumation rates than the eastern one. Such differential exhumation was accommodated in the northern portion of the belt thanks to reverse motion along the Internal Houiller Fault, which occurred in a convergent transcurrent framework. To the south, it was accommodated instead by normal reactivation of the Brianc¸onnais Front and by activity of the Longitudinal Fault System, which occurred in a divergent transcurrent framework. The tectonic activity affecting the axial sector of the belt, in a context of regional dextral strike slip, is coeval with the forward propagation of the external thrusts, and of similar magnitude. We suggest that the contrasting kinematic regimes (i.e., convergent versus divergent transcurrence) observed in the Western Alps moving along strike were responsible of the increasing exhumation rates toward the north, revealed in both blocks by the along-strike age gradient. The higher exhumation rates recognized northward would be related to an increasing importance of crustal shortening that promoted erosion during the late stages of exhumation of the belt

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“…This is not the case around Plateau, particularly those parts which relate to the region east of its margins, however. Numerous thermochronological studies of the Eastern Himalayan syntaxis (Figure 1) [Kasuya and Naeser, 1988]. All of these points suggest that the temperature limits of a zircon PAZ are dependent on the time-temperature history of the sample host rocks, the degree of radiation damage contained in the crystals on entering the PAZ, and whether the stratigraphic/structural extents of fossil PAZs are picked from the central age for samples or from a subset (least thermally stable) of the dated grains within samples.…”

Section: Introductionmentioning

confidence: 90%

Tectonics and denudation adjacent to the Xianshuihe Fault, eastern Tibetan Plateau: Constraints from fission track thermochronology

Xu¹,

Kamp²

2000

J. Geophys. Res.

180

144

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The Xianshuihe‐Xiaojiang fault system extending from eastern Tibet to central Yunnan, China, is a major left‐shear structural boundary, accommodating the clockwise rotation of crustal rocks between the Eastern Himalayan syntaxis and the South China Block. Zircon and apatite fission track (FT) data are reported for 111 samples of basement collected from both sides of the northern part of this fault and spanning 300 km across the eastern margin of the Tibetan Plateau, where its mean elevation drops from 3500 to 1500 m above sea level. The zircon FT ages define two fossil partial annealing zones at different elevations, one fossilised at circa 130 Ma, and the other at circa 21 Ma as a result of cooling probably via regional denudation. The apatite FT ages are mostly less than 25 Ma, but a few granitoids higher up on the plateau retain late Cretaceous apparent ages. Within the apatite FT data with Neogene ages, there may be several partial annealing zones, with mixture modeling identifying age components suggestive of discrete cooling phases at circa 22, 7 and 2 Ma. The first‐order pattern of the minimum amount of Neogene denudation for a section across the plateau margin immediately northeast of Xianshuihe Fault suggests that a relatively uniform 4–6 km has been eroded from the inner part of the plateau margin, increasing to 7–10 km at Kangding, where the oldest rocks (Precambrian) are exposed, and then decreasing markedly into Sichuan Basin. These new FT data combined with published FT data suggest that the present extent of the Tibetan Plateau was defined during the early Miocene.

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The effect of α-damage of the fission-track annealing in zircon

Cited by 17 publications

References 0 publications

Implications for Timing of Andean Uplift from Thermal Resetting of Radiation‐Damaged Zircon in the Cordillera Huayhuash, Northern Peru

Implications for Timing of Andean Uplift from Thermal Resetting of Radiation‐Damaged Zircon in the Cordillera Huayhuash, Northern Peru

Miocene to Present differential exhumation in the Western Alps: Insights from fission track thermochronology

Tectonics and denudation adjacent to the Xianshuihe Fault, eastern Tibetan Plateau: Constraints from fission track thermochronology

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