Metamorphism in the Adirondacks. I. Petrology, Pressure and Temperature

Bohlen, Steven R.; Valley, John W.; Essene, Eric J.

doi:10.1093/petrology/26.4.971

Cited by 197 publications

(134 citation statements)

References 36 publications

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“…1.09-1.05 Ga. Peak metamorphic mineral assemblages in these rocks record temperatures of 750°-850°C and pressures of 6-9 MPa consistent with mid-crustal granulite-facies conditions (Bohlen et al 1985;Florence et al 1995;Kitchen and Valley 1995;Darling et al 2004;Storm and Spear 2005). There has been less certainty about when these granulite-facies P, T conditions developed in the AHT, but robust evidence has recently been provided by mineral assemblages, coupled with zircon dating, in the famous Gore Mountain garnet mine which exposes the world's largest garnet crystals (average diameter ~18 cm, largest diameter 1 m; McLelland and Selleck 2012).…”

mentioning

confidence: 68%

“…High grade Shawinigan metamorphism affected the entire AHT resulting in assemblages above the second sillimanite isograd and caused widespread anatexis in metapelite (Heumann et al 2006;Bickford et al 2008;McLelland et al 2010a). To a large extent, Shawinigan effects in the AHT are overprinted by the intense granulite facies Ottawan Orogeny that produced temperatures of ~750°-850°C and pressures of 6-9 MPa in the AHT (Bohlen et al 1985;Kitchen and Valley 1995;Darling et al 2004;Storm and Spear 2005; among others) and reset titanite ages to ca. 1.03 Ga and hornblende 40 Ar/ 39 Ar ages to ca.…”

Section: Geology Of the Adirondack Mountainsmentioning

confidence: 99%

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Tectonic Evolution of the Adirondack Mountains and Grenville Orogen Inliers within the USA

McLelland

Selleck

Bickford³

2013

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Recent investigations in geochronology and tectonics provide important new insights into the evolution of the Grenville Orogen in North America. Here, we summarize results of this research in the USA and focus upon ca. 1.4–0.98 Ga occurrences extending from the Adirondack Mountains to the southern Appalachians and Texas. Recent geochronology (mainly by U/Pb SHRIMP) establishes that these widely separated regions experienced similar tectonomagmatic events, i.e., the Elzevirian (ca. 1.25–1.22 Ga), Shawinigan (ca. 1.2–1.14 Ga), and Grenvillian (ca. 1.09–0.98 Ga) orogenies and associated plate interactions. Notwithstanding these commonalities, Nd model ages and Pb isotopic mapping has revealed important differences that are best explained by the existence of contrasting compositions of deep crustal reservoirs beneath the Adirondacks and the southern Appalachians. The isotopic compositions for the Adirondacks lie on the same Pb–Pb array as those for the Grenville Province, the Granite-Rhyolite Province and the Grenvillian inliers of Texas suggesting that they all developed on Laurentian crust. On the other hand, data from the southern Appalachians are similar to those of the Sunsas Terrane in Brazil and suggest that Amazonian crust with these Pb–Pb characteristics was thrust onto eastern Laurentia during its Grenvillian collision with Amazonia and subsequently transferred to the latter during the late Neoproterozoic breakup of the supercontinent, Rodinia, and the formation of the Iapetus Ocean. The ca. 1.3–1.0 Ga Grenville Orogen is also exposed in the Llano Uplift of Texas and in small inliers in west Texas and northeast Mexico. The Llano Uplift contains evidence for a major collision with a southern continent at ca. 1.15–1.12 Ga (Kalahari Craton?), magmatic arcs, and back-arc and foreland basins, all of which are reviewed. The Grenvillian Orogeny is considered to be the culminating tectonic event that terminated approximately 500 m.y. of continental margin growth along southeastern Laurentia by accretion, continental margin arc magmatism, and metamorphism. Accordingly, we briefly review the tectonic and magmatic histories of these Paleoproterozoic and Mesoproterozoic pre-Grenvillian orogens, i.e., Penokean, Yavapai, and Mazatzal as well as the Granite-Rhyolite Province and discuss their ~5000 km transcontinental span.SOMMAIREDes recherches récentes en géochronologie et en tectonique révèlent d’importants faits nouveaux sur l’évolution de l’orogénie de Grenville en Amérique du Nord. Nous présentons ici un sommaire des résultats de cet effort de recherche aux USA en mettant l’accent sur les indices datés entre env. 1,4 et 0,98 Ga, à partir des monts Adirondack jusqu’au sud des Appalaches et au Texas. Des données géochronologiques récentes (par microsonde SHRIMP principalement) indiquent que les roches de ces régions très éloignées les unes des autres ont subies l’effet d’épisodes tectonomagmatiques similaires, par exemple, aux orogenèses de l’Elzévirien (env. 1.25–1.22 Ga), de Shawinigan (env. 1.2–1.14 Ga), et du Grenvillien (env. 1.09–0.98 Ga), ainsi que des interactions des plaques associées. Malgré ces points communs, la chronologie Nd et la cartographie isotopique Pb a révélé des différences importantes qui s’expliquent plus aisément par des compositions contrastées des réservoirs profonds de croûte sous les Adirondacks et le sud des Appalaches. Les compositions isotopiques des Adirondacks sont de la même gamme Pb-Pb que ceux de la Province de Grenville, de la Province Granite-rhyolite et des boutonnières grenvilliennes du Texas, suggérant qu'ils se sont tous développées sur la croûte des Laurentides. Par ailleurs, les données des Appalaches du sud sont semblables à celles du terrane de Sunsas au Brésil, ce qui incite à penser que la croûte amazonienne, avec de telles caractéristiques Pb-Pb, a été poussée sur la portion est de Laurentia lors de sa collision grenvillienne avec l’Amazonie puis laissée à cette dernière au cours de la rupture du supercontinent Rodinia vers la fin du Néoprotérozoïque, avec la formation de l'océan Iapetus. L’orogène de Grenville (1,3 à 1,0 Ga env.) est également exposé dans le soulèvement de Llano au Texas et dans de petites boutonnières dans l'ouest du Texas et le nord du Mexique. Le soulèvement de Llano montre des indices d'une collision majeure avec un continent au sud, entre env. 1,15 et 1,12 Ga (craton de Kalahari?), des zones d’arcs magmatiques, d'arrière-arc et de bassin d'avant-pays, chacun étant présenté ci-dessous. L'orogenèse de Grenville est considéré comme l'événement tectonique culminant qui marqué la fin d’une période d’environ 500 ma d’accroissement de la marge continentale le long de la bordure sud-est de la Laurentie, par accrétion, magmatisme d’arc de marge continentale, et métamorphisme. C’est pourquoi, nous passons brièvement en revue l'histoire tectonique et magmatique de ces orogènes pré-grenvilliennes paléoprotérozoïques et mésoprotérozoïques, pénokéenne, de Yavapai, et de Mazatzal ainsi que la Province de Granite-rhyolite, et discutons de son étendue sur env. 5 000 km.

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mentioning

confidence: 68%

Section: Geology Of the Adirondack Mountainsmentioning

confidence: 99%

Tectonic Evolution of the Adirondack Mountains and Grenville Orogen Inliers within the USA

McLelland

Selleck

Bickford³

2013

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“…Those who both calibrated thermometers and barometers and tested them in the Grenville Province included Eric Essene and his many co-workers (e.g. Essene 1977, 1980;Essene 1982;Perkins et al 1982;Bohlen et al 1985;Anovitz and Essene 1990;Tuccillo et al 1990), and Indares andMartignole (1984, 1985). Geothermometry on upper amphibolite-and granulite-facies gneisses in the Grenville hinterland revealed temperatures in the range 700 ± 50°C or higher, a not unexpected result although subsequently shown to commonly underestimate peak T due to post-peak resetting (the granulite uncertainty principle; Frost and Chacko 1989).…”

Section: Geothermobarometrymentioning

confidence: 99%

Tectonic Setting and Evolution of the Grenville Orogen: An Assessment of Progress Over the Last 40 Years

Rivers

2015

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SUMMARYThe Grenville Province is known for its high grade of metamorphism, complex ductile gneissic structure, and polyphase reworking, features indicative of residence in the deep crust (orogenic infrastructure) that hamper recognition of protoliths and original relationships and render tectonic interpretations especially challenging. This paper charts the evolving understanding from the 'Grenville Problem' of the 1950s before the plate tectonic paradigm, through a speculative quasiplate tectonic stage in the 1970s that effectively proved to be a dead end, and the first constrained plate tectonic models for pre-Grenvillian Laurentia in the 1980s, to the recent LHO (large hot orogen) and collapsed LHO models for the Grenville Orogen itself. The collapsed LHO model is based on the finding that significant amounts of the superstructure (upper orogenic crust) are preserved, and that the present crustal architecture can be explained by tectonic juxtaposition of infrastructure and superstructure in a late extensional event associated with crustal-scale collapse of a high-strain channel under an orogenic plateau. Conceptual breakthroughs and critical datasets assembled in the period 1980-2000 that were influential in guiding tectonic thinking are discussed and it is argued that present understanding was contingent on the results of 2-D numerical forward modelling of orogenesis, in particular the LHO experiments and the more recent models of orogenic collapse. As a result, for the first time a conceptual plate tectonic model for the convergence and collapse stages of the Grenville Orogen based on empirical field data (the inverse model) is broadly supported by numerical forward-modelling experiments constrained by physically plausible processes in a LHOand both are available for future testing and refinement. Moreover, they may also have application to other enigmatic high-grade Proterozoic orogens that have resisted simple incorporation within the plate tectonic narrative.

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“…However the difference in lithologies and PT conditions across the boundary is indistinct . This has led to conflicting reports on the nature of the shear zone, in which many workers have argued that the CCSZ does not represent a tectonically significant boundary (e.g., Geraghty et al 1981;Bohlen et al 1985). The striking difference in metamorphic ages precludes the idea that the CCSZ is an insignificant feature although the geologic similarities between the Highlands and the Lowlands need to be explained.…”

Section: Geologic Settingmentioning

confidence: 99%

“…2). However, neither pressure-temperature conditions nor lithologies are drastically different across this boundary leading to considerable controversy regarding the nature and significance of the CCSZ (Wiener et al 1984;Bohlen et al 1985;McLelland et al 1996).…”

Section: Introductionmentioning

confidence: 99%

Early History of the Carthage‐Colton Shear Zone, Grenville Province, Northwest Adirondacks, New York (U.S.A.)

Streepey

Johnson

Mezger

et al. 2001

The Journal of Geology

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A B S T R A C TThe Adirondack Mountains expose two distinct tectonic elements of the Proterozoic Grenville Province of northeastern North America: the Adirondack Lowlands and Highlands. The Lowlands are located along the eastern edge of the Metasedimentary Belt, and the Highlands form the western portion of the Granulite Terrane. The two are separated by the Carthage-Colton Shear Zone (CCSZ). U/Pb titanite and 40 Ar hornblende ages in the Lowlands are ca. 100 m.yr. older than in the Highlands, across the CCSZ. While both the Lowlands and the Highlands record a history of metamorphism during the Elzevirian Orogeny (ca. 1150 Ma), only the Highlands record evidence of a major phase of Grenvillian thermotectonic activity (Ottawan Orogeny) at ca. 1090-1030 Ma. Proposed tectonic models require that the Lowlands were either laterally separated from the Highlands or were at structurally higher levels during this metamorphism. New U/Pb and Ar hornblende ages at 1000 Ma within the shear zone. Thermobarometric constraints indicate that deformation occurred under granulite-facies conditions. Therefore, titanite and hornblende ages are interpreted as cooling ages from a ca. 1050-1030-Ma event. An early transpressive shearing event at ca. 1040 Ma, combined with structural data in the Dana Hill metagabbro that indicate strike-slip displacement along the CCSZ, suggests significant lateral displacement between the Lowlands and the Highlands during the ca. 1090-1030-Ma Ottawan Orogeny, prior to later extension along the CCSZ.

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Metamorphism in the Adirondacks. I. Petrology, Pressure and Temperature

Cited by 197 publications

References 36 publications

Tectonic Evolution of the Adirondack Mountains and Grenville Orogen Inliers within the USA

Tectonic Evolution of the Adirondack Mountains and Grenville Orogen Inliers within the USA

Tectonic Setting and Evolution of the Grenville Orogen: An Assessment of Progress Over the Last 40 Years

Early History of the Carthage‐Colton Shear Zone, Grenville Province, Northwest Adirondacks, New York (U.S.A.)

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