Intragrain oxygen isotope zoning in titanite by <scp>SIMS</scp>: Cooling rates and fluid infiltration along the Carthage‐Colton Mylonite Zone, Adirondack Mountains, <scp>NY</scp>,<scp> USA</scp>

Bonamici, Chloë; Kozdon, Reinhard; Ushikubo, T.; Valley, John W.

doi:10.1111/jmg.12059

Cited by 33 publications

(56 citation statements)

References 63 publications

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“…2B,C) revealed the presence of coreto-rim O-isotope zoning: twelve grains showed uniformly steep δ 18 O gradients within 50-200 μm of the grain rims, consistent with arrested diffusive exchange of O (Bonamici et al, 2014). Numerical modeling of the O-isotope zoning profiles indicated relatively rapid cooling rates of 30-70°C/my over the temperature range of 700-500°C (Bonamici et al, 2014). Observed O-isotope zoning in the Harrisville titanite indicates that these grains are also candidates to preserve diffusionrelated U-Pb zoning.…”

Section: Geological Setting and Backgroundmentioning

confidence: 80%

“…Following SIMS analysis, quantitative compositional data are collected within 10-30 μm of every SIMS pit in the unknown by electron microprobe in order to calculate Ti formula atoms and apply the bias correction. All Harrisville SIMS δ 18 O data are reported Bonamici et al (2014) and SIM δ 18 O data for the six titanite grains of this study are available in Appendix 2. Several analyses were discarded (grayed out in figures) because of significant overlap with inclusions or large fractures observed by post-analysis SEM imaging.…”

Section: Methodsmentioning

confidence: 99%

“…Instrumental bias in the ion microprobe measurement of δ 18 O in titanite correlates linearly over the compositional range of interest (~0.75-1.0 formula atoms Ti) with the abundance of Ti in the octahedral site, which commonly also contains Al 3+ and Fe 3+ . Because the exact correction for bias varies with each analysis session, three well-characterized, chemically (major elements) and isotopically (δ 18 O) homogeneous titanite standards (Bonamici et al, 2014) are measured and bracketed by analyses of the WiscSIMS in-house quartz standard (UWQ-1; Kelly et al, 2007) during each session. Following SIMS analysis, quantitative compositional data are collected within 10-30 μm of every SIMS pit in the unknown by electron microprobe in order to calculate Ti formula atoms and apply the bias correction.…”

Section: Methodsmentioning

confidence: 99%

“…Previous studies found evidence for multiple deformation events within the broader CCMZ (Wiener, 1983;Baird and MacDonald, 2004), including an earlier oblique-slip event (Geraghty et al, 1981;Streepey et al, 2001;Johnson et al, 2004) and a later extensional event . These events are also represented in the Harrisville outcrops (Bonamici et al, 2014), where an early protomylonite foliation (S 1 ) is crosscut by ≥ 100 steeply dipping ultramylonite shear zones (S 2 ), which are themselves transposed by a later, moderately dipping foliation (S 3 ) (Fig. 3).…”

Section: Geological Setting and Backgroundmentioning

confidence: 98%

“…Titanite grains for this study were sampled from two outcrops within the Carthage-Colton Mylonite Zone (CCMZ) near Harrisville, New York ( Fig. 2; Cartwright et al, 1993;Lamb, 1993;Bonamici et al, 2011Bonamici et al, , 2014. The CCMZ is a major NNE-striking structure that juxtaposes the upper-amphibolite-facies Adirondack Lowlands to the northwest and the granulite-facies central Adirondack Highlands to the southeast ( Fig.…”

Section: Geological Setting and Backgroundmentioning

confidence: 99%

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Combined oxygen-isotope and U-Pb zoning studies of titanite: New criteria for age preservation

et al. 2015

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Titanite is an important U-Pb chronometer for dating geologic events, but its high-temperature applicability depends upon its retention of radiogenic lead (Pb). Experimental data predict similar rates of diffusion for lead (Pb) and oxygen (O) in titanite at granulite-facies metamorphic conditions (T = 650-800°C). This study therefore investigates the utility of O-isotope zoning as an indicator for U-Pb zoning in natural titanite samples from the Carthage-Colton Mylonite Zone of the Adirondack Mountains, New York. Based on previous field, textural, and microanalytical work, there are four generations (types) of titanite in the study area, at least two of which preserve diffusion-related δ 18 O zoning. U-Th-Pb was analyzed by SIMS along traverses across three grains of type-2 titanite, which show well-developed diffusional δ 18 O zoning, and one representative grain from each of the other titanite generations. Type-2 and type-4 titanites show broadly core-to-rim decreasing 206 Pb/ 238 U zoning, consistent with Pb diffusion at higher temperatures, and uniform or even slightly increasing 206 Pb/ 238 U near grain rims, indicating subsequent recrystallization and/or new growth below the Pb blocking temperature. Type-2 and type-4 grain cores preserve ca. 1160 Ma ages that correlate with the anorthositemangerite-charnockite-granite magmatic phase of the Grenville orogeny, whereas grain rims give ca. 1050 Ma 206 Pb/ 238 U ages that coincide with the culminating Ottawan phase. The type-3 titanite grain was sampled from a vein and yields 206 Pb/ 238 U dates older than the syenite into which the vein was emplaced; accordingly, its 206 Pb/ 238 U dates are interpreted as indicating excess uncorrected common Pb. Type-2 grains with recrystallized or shear-eroded margins show truncated or reversed 206 Pb/ 238 U zoning but retain symmetrically decreasing δ 18 O zoning, consistent with grain margin modification following arrest of Pb diffusion but before arrest of O diffusion. It is concluded that O diffusion was slightly faster than Pb diffusion in Adirondack titanites at the conditions of (local) peak Ottawan metamorphism, making δ 18 O zoning a useful discriminator of closed-system age domains that did not suffer Pb loss. In addition, the small offset in the O and Pb partial retention zones constrains the timing and temperature of oblique-slip deformation along the Carthage-Colton Mylonite Zone: the details of porphyroclast microstructure and zoning data show that the oblique-slip shear zones were active at ca. 1050 Ma, with deformation initiating near the peak of Ottawan metamorphism at~700°C and continuing through the O blocking temperature at~550°C.Published by Elsevier B.V.

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Section: Geological Setting and Backgroundmentioning

confidence: 80%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Geological Setting and Backgroundmentioning

confidence: 98%

Section: Geological Setting and Backgroundmentioning

confidence: 99%

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Combined oxygen-isotope and U-Pb zoning studies of titanite: New criteria for age preservation

et al. 2015

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Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: Implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano‐Pan‐African Orogeny

et al. 2016

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U‐Pb and Hf zircon (sensitive high‐resolution ion microprobe ‐SHRIMP‐ and laser ablation‐inductively coupled plasma‐mass spectrometry ‐LA‐ICP‐MS‐), Ar/Ar hornblende and muscovite, and Rb‐Sr whole rock‐muscovite isochron data from the mylonites of the Sarandí del Yí Shear Zone, Uruguay, were obtained in order to assess the tectonothermal evolution of this crustal‐scale structure. Integration of these results with available kinematic, structural, and microstructural data of the shear zone as well as with geochronological data from the adjacent blocks allowed to constrain the onset of deformation along the shear zone at 630–625 Ma during the collision of the Nico Pérez Terrane and the Río de la Plata Craton. The shear zone underwent dextral shearing up to 596 Ma under upper to middle amphibolite facies conditions, which was succeeded by sinistral shearing under lower amphibolite to upper greenschist facies conditions until at least 584 Ma. After emplacement of the Cerro Caperuza granite at 570 Ma, the shear zone underwent only cataclastic deformation between the late Ediacaran and the Cambrian. The Sarandí del Yí Shear Zone is thus related to the syncollisional to postcollisional evolution of the amalgamation of the Río de la Plata Craton and the Nico Pérez Terrane. Furthermore, the obtained data reveal that strain partitioning and localization with time, magmatism emplacement, and fluid circulation are key processes affecting the isotopic systems in mylonitic belts, revealing the complexity in assessing the age of deformation of long‐lived shear zones.

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U–Pb isotopic dating of titanite microstructures: potential implications for the chronology and identification of large impact structures

Papapavlou

Darling

Moser

et al. 2018

Contrib Mineral Petrol

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Identifying and dating large impact structures is challenging, as many of the traditional shock indicator phases can be modified by post-impact processes. Highly robust accessory phases, such as zircon, while faithful recorders of shock wave passage, commonly respond with partial U-Pb age resetting during impact events. Titanite is an accessory phase with lower Pb closure temperature than many other robust chronometers, but its potential as indicator and chronometer of impact-related processes remains poorly constrained. In this study, we examined titanite grains from the Sudbury (Ontario, Canada) and Vredefort (South Africa) impact structures, combining quantitative microstructural and U-Pb dating techniques. Titanite grains from both craters host planar microstructures and microtwins that show a common twin-host disorientation relationship of 74° about <102>.In the Vredefort impact structure, the microtwins deformed internally and developed high and low-angle grain boundaries that resulted in the growth of neoblastic crystallites. U-Pb isotopic dating of magmatic titanite grains with deformation microtwins from the Sudbury impact structure yielded a 207 Pb/ 206 Pb age of 1851 ± 12 Ma that records either the shock heating or the crater modification stage of the impact event. The titanite grains from the Vredefort impact structure yielded primarily pre-impact ages recording the cooling of the ultra-high temperature Ventersdorp event but domains with microtwins or planar microstructures show evidence of U-Pb isotopic disturbance. Despite that the identified microtwins are not diagnostic of shock-metamorphic processes, our contribution demonstrates that titanite has great potential to inform studies of the terrestrial impact crater record.

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Intragrain oxygen isotope zoning in titanite by SIMS: Cooling rates and fluid infiltration along the Carthage‐Colton Mylonite Zone, Adirondack Mountains, NY, USA

Cited by 33 publications

References 63 publications

Combined oxygen-isotope and U-Pb zoning studies of titanite: New criteria for age preservation

Combined oxygen-isotope and U-Pb zoning studies of titanite: New criteria for age preservation

Timing of deformation in the Sarandí del Yí Shear Zone, Uruguay: Implications for the amalgamation of western Gondwana during the Neoproterozoic Brasiliano‐Pan‐African Orogeny

U–Pb isotopic dating of titanite microstructures: potential implications for the chronology and identification of large impact structures

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