Lyon Mountain ferroan leucogranite suite: Magmatic response to extensional thinning of overthickened crust in the core of the Grenville orogen

Chiarenzelli, Jeffrey R.; Selleck, Bruce; Lupulescu, Marian; Regan, Sean P.; Bickford, M.E.; Valley, Peter M.; McLelland, James M.

doi:10.1130/b31697.1

Cited by 14 publications

(40 citation statements)

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“…A second trend within the Highlands is that granitic [34] and silicocarbonate pegmatites in the eastern Adirondack Highlands appear to be 20-30 million years younger than those in the western part near the CCsz. Chiarenzelli et al [35] noted a similar trend in the Lyon Mountain granite, suggesting that orogenic collapse may have begun in the northwest Lowlands and propagated eastward over several tens of millions of years. If so, the spatial trends in pegmatitic and leucogranitic rocks noted across the Adirondacks may be a function of time and the duration or magnitude of fault motion.…”

Section: Age Of the Silicocarbonate Pegmatitesmentioning

confidence: 87%

“…The occurrence in Stone Valley, near Colton, NY, unequivocally ties the emplacement of some silicocarbonate melts to brittle faulting, late in the movement history of the CCsz. The timing is synchronous with uplift, exhumation, leucogranite intrusion, and widespread fluid infiltration of the Adirondack Region [35,36,[40][41][42][43][44][45][46].…”

Section: Tectonic Implicationsmentioning

confidence: 95%

“…Silicocarbonate intrusion (circa 1050 Ma) corresponds with the intrusion of the Lyon Mountain granite suite and associated granitic pegmatites [33][34][35]45]. It also occurred during the intrusion of the iron oxide-apatite deposits of the eastern Adirondacks and associated albitization and/or alkali-metasomatism of the Lyon Mountain granite host (35,42,45,46).…”

Section: Tectonic Implicationsmentioning

confidence: 99%

“…A major question in the Adirondacks is the extent and timing of deformation associated with the Ottawan orogenic event (circa 1090-1020). While the Lowlands are thought to be part of the orogenic lid, largely escaping Ottawan effects and lacking Ottawan intrusive rocks, the Highlands record both Shawinigan and geographically limited Ottawan melting of pelitic rocks [47,48] and, presumably, associated deformation and widespread late ferroan leucogranite intrusion [35]. Until relatively recently, the major structural grain in the Highlands was thought to be Ottawan in age.…”

Section: Tectonic Implicationsmentioning

confidence: 99%

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Age and Origin of Silicocarbonate Pegmatites of the Adirondack Region

et al. 2019

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Silicocarbonate pegmatites from the southern Grenville Province have provided exceptionally large crystal specimens for more than a century. Their mineral parageneses include euhedral calc–silicate minerals such as amphibole, clinopyroxene, and scapolite within a calcite matrix. Crystals can reach a meter or more in long dimension. Minor and locally abundant phases reflect local bedrock compositions and include albite, apatite, perthitic microcline, phlogopite, zircon, tourmaline, titanite, danburite, uraninite, sulfides, and many other minerals. Across the Adirondack Region, individual exposures are of limited aerial extent (<10,000 m2), crosscut metasedimentary rocks, especially calc–silicate gneisses and marbles, are undeformed and are spatially and temporally associated with granitic pegmatites. Zircon U–Pb results include both Shawinigan (circa 1165 Ma) and Ottawan (circa 1050 Ma) intrusion ages, separated by the Carthage-Colton shear zone. Those of Shawinigan age (Lowlands) correspond with the timing of voluminous A-type granitic magmatism, whereas Ottawan ages (Highlands) are temporally related to orogenic collapse, voluminous leucogranite and granitic pegmatite intrusion, iron and garnet ore development, and pervasive localized hydrothermal alteration. Inherited zircon, where present, reflects the broad range of igneous and detrital ages of surrounding rocks. Carbon and oxygen isotopic ratios from calcite plot within a restricted field away from igneous carbonatite values to those of typical sedimentary carbonates and local marbles. Collectively, these exposures represent a continuum between vein-dyke and skarn occurrences involving the anatexis of metasedimentary country rocks. Those of Ottawan age can be tied to movement and fluid flow along structures accommodating orogenic collapse, particularly the Carthage-Colton shear zone.

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Section: Age Of the Silicocarbonate Pegmatitesmentioning

confidence: 87%

Section: Tectonic Implicationsmentioning

confidence: 95%

Section: Tectonic Implicationsmentioning

confidence: 99%

Section: Tectonic Implicationsmentioning

confidence: 99%

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Age and Origin of Silicocarbonate Pegmatites of the Adirondack Region

et al. 2019

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“…Orogenic collapse of the Ottawan orogen occurred synchronously with intrusion of the Lyon Mountain Granite Gneiss into the Adirondack Highlands and extension along both the CCMZ and East Adirondack shear zone at ca. 1060-1030 Ma Bickford et al, 2008;Wong et al, 2011;Chiarenzelli et al, 2017;Fig. 1B).…”

Section: ■ Introductionmentioning

confidence: 99%

Late Ottawan orogenic collapse of the Adirondacks in the Grenville province of New York State (USA): Integrated petrologic, geochronologic, and structural analysis of the Diana Complex in the southern Carthage-Colton mylonite zone

Baird

2020

Geosphere

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Crustal-scale shear zones can be highly important but complicated orogenic structures, therefore they must be studied in detail along their entire length. The Carthage-Colton mylonite zone (CCMZ) is one such shear zone in the northwestern Adirondacks of northern New York State (USA), part of the Mesoproterozoic Grenville province. The southern CCMZ is contained within the Diana Complex, and geochemistry and U-Pb zircon geochronology demonstrate that the Diana Complex is expansive and collectively crystallized at 1164.3 ± 6.2 Ma. Major ductile structures within the CCMZ and Diana Complex include a northwest-dipping penetrative regional mylonitic foliation with north-trending lineation that bisects a conjugate set of mesoscale ductile shear zones. These ductile structures formed from the same 1060–1050 Ma pure shear transitioning to a top-to-the-SSE shearing event at ∼700 °C. Other important structures include a ductile fault and breccia zones. The ductile fault formed immediately following the major ductile structures, while the breccia zones may have formed at ca. 945 Ma in greenschist facies conditions. Two models can explain the studied structures and other regional observations. Model 1 postulates that the CCMZ is an Ottawan orogeny (1090–1035 Ma) thrust, which was later reactivated locally as a tectonic collapse structure. Model 2, the preferred model, postulates that the CCMZ initially formed as a subhorizontal mid-crustal mylonite zone during collapse of the Ottawan orogen. With continued collapse, a metamorphic core complex formed and the CCMZ was rotated into is current orientation and overprinted with other structures.

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