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The tectonomagmatic evolution of the southern Coast Mountains batholith, British Columbia reveals the relation of magmatic tempo, deformation, and relative plate motions which inform models for growth of continental crust and convergent plate dynamics. Magmatism in the southern batholith is episodic, derived primarily from the mantle, and reflects lower‐plate dynamics (Cecil et al., 2018, https://doi.org/10.1029/2018gc007874, 2021, https://doi.org/10.1130/ges02361.1). New field, structural, geochronologic, and geobarometric results from the southern batholith document three episodes of deformation, each spatially and temporally coincident with a high magmatic flux event (HFE). Sinistral faulting (<117–103 Ma) and penetrative deformation (110–90 Ma) occurred only within two distinct areas affected by a HFE at 114–102 Ma. Following a magmatic lull, crustal shortening occurred after 90 Ma and before 72 Ma within the region affected by a second HFE (85–70 Ma). After 70 Ma and before 53 Ma, >100 km of dextral slip occurred on the Coast shear zone and minor shortening affected 64–62 Ma plutons, overlapping with the 64–61 Ma HFE. Thus, at the crustal level exposed in the southern batholith, the timing and location of deformation is linked to magmatic tempo and the style of deformation varies through time. These results suggest that magmatic HFE modulate the timing and location of deformation while relative plate motions during HFE influence the style of deformation. Periods of deformation in batholiths may thus record high‐flux magmatic events and coeval plate motion but do not necessarily signal changes in plate motions. Plain Language Summary: Understanding how continents grow and the dynamics of plate motions relies on knowing the geologic history of convergent margins. Here we present new data on the evolution of a Late Cretaceous‐Paleogene convergent margin preserved in the southern Coast Mountains batholith in British Columbia. Magmatism in the southern batholith is episodic, derived primarily from the mantle, and reflects lower‐plate dynamics (Cecil et al., 2018, https://doi.org/10.1029/2018gc007874, 2021, https://doi.org/10.1130/ges02361.1). Our new results show that the southern batholith experienced three episodes of deformation, each one coincident with one of three high‐magmatic‐flux events. This pattern suggests that the timing and location of deformation here is linked to magmatic tempo and the style of deformation varies independently. Thus, we conclude that magmatic patterns modulate the tempo and location of deformation and that relative plate motions during episodes of high‐flux magmatism control the style of deformation. Periods of deformation in batholiths may thus record high‐flux magmatic events and coeval plate motion but do not necessarily signal changes in plate motions. Key Points: The location and timing of deformation and high‐flux magmatism coincide across the southern Coast Mountains batholith between ca. 115 and 50 MaHigh‐flux magmatism controls the timing and location of deformation; style of deformation reflects plate motion during high‐flux magmatismDextral slip exceeded 100 km on the intra‐arc Coast shear zone (<70–53) Ma and caused Salinian‐style repetition of the batholith [ABSTRACT FROM AUTHOR]

The McCoy Mountains Formation (McMF) in southern California–Arizona preserves an anomalously thick record of sedimentation during the Mesozoic at a critical time when western North America experienced contrasting tectonic events related to intracontinental rifting along the Mexican Border rift system and consolidation of the North American Cordilleran system. The spaciotemporal interactions among these events and the development of the McCoy basin challenge our understanding of the evolution of the southern extent of North America. At its type locality in the McCoy Mountains, the McMF consists of ~ 7 km of low‐grade metasedimentary rocks, originally interpreted as meandering fluvial to alluvial‐fan deposits. Uncertainty in the initial timing of sedimentation in the McCoy basin has resulted in multiple tectonic models. We measured ~ 7160 m of detailed stratigraphy and present new sedimentological and detrital zircon results showing that the McCoy basin was occupied by deep‐water turbidite systems. These systems deposited an upward‐coarsening succession of fine‐ to coarse‐grained detritus during the Cretaceous (ca. 137–70 Ma). Provenance data indicate that the McCoy basin received sediment from Proterozoic basement rocks and metamorphosed Palaeozoic to early Mesozoic sedimentary units. These source rocks are equivalent to the stratigraphy found in the Grand Canyon and Colorado Plateau regions and were likely shed from the southward‐advancing Maria fold‐thrust belt and possibly the southern Sevier belt in southern Nevada and California. These results, combined with subsidence curves typical of foreland basins, favour deposition within a subaqueous flexural foreland basin system. The presence of a Cretaceous foreland basin this far southwest challenges previously proposed models and suggests that the contractional tectonic regime associated with the North American Cordillera extended into the southwestern most United States during the Early–Late Cretaceous. [ABSTRACT FROM AUTHOR]

U-Pb age spectra of detrital zircons in samples from the Paleogene Colton Formation in the Uinta Basin of northeastern Utah and the Late Cretaceous McCoy Mountains Formation of southwestern Arizona (United States) are statistically indistinguishable. This finding refutes previous inferences that arkosic detritus of the Colton was derived from cratonic basement exposed by Laramide tectonism, and instead establishes the Cordilleran magmatic arc (which also provided sediment to the McCoy Mountains Formation) as the primary source. Given the existence of a north-south-trending drainage divide in eastern Nevada and the north-northeast direction of Laramide paleoflow throughout Arizona and southern Utah, we infer that a large river system headed in the arc of the Mojave region flowed northeast ~700 km to the Uinta Basin. Named after its source area, this Paleogene California River would have been equal in scale but opposite in direction to the modern Green River-Colorado River system, and the timing and causes of the subsequent drainage reversal are important constraints on the tectonic evolution of the Cordillera and the Colorado Plateau. © 2010 Geological Society of America.

Cape Kiber on the Arctic coast of Chukotka, northeast Russia, consists of a granite intruding Devonian (and older?) strata in the core of a large southeast trending anticline. These strata are structurally overlain by Carboniferous and younger strata. AU-Pb age of 351.4 ±5.6 (2σ)Ma shows that the granite is Early Carboniferous in age. A large granite cobble extracted from a Carboniferous conglomerate produced a Late Devonian or Early Carboniferous U-Pb age of ~355-361 Ma. Also, a deformed and altered granitic dyke yielded an age of 363.7 ± 5.7 (2cr) Ma. Major and trace elements suggest a syn-collisional (orogenic) setting. The granite's (biotite) Ar release spectrum is reset. The granitic dyke also shows a disturbed Ar-Ar whole-rock spectrum implying an Early Cretaceous age (~122-130 Ma) for closure of the Ar system. We interpret this as due to widespread greenschist metamorphism accompanying regional deformation of the Anyuy-Chukotka Fold Belt that accompanied closure of the South Anyuy Ocean. Regionally, this event predates deposition of Aptian and Albian strata and the eruption of Okhotsk--Chukotsk magmatic rocks. An Ar-Ar (biotite) plateau age of 96.4 [+ or -]1.0 (2σ) Ma from a mildly deformed, lamprophyre dyke reflects intrusion in a setting of regional extension. Its deformation reflects a younger tectonic event. The record of Devonian--Carboniferous magmatism and early Carboniferous unroofing is younger and less complex than that of Arctic Alaska. However, evidence for Early Devonian (Caledonian) or Late Devonian (Ellesmerian) deformation could have been masked by intense Mesozoic deformation. Outcrop data and geochronology support and refine regional interpretations of Early Cretaceous deformation and mineral growth accompanying accretion of Chukotka to north Asia, followed by regional extension and subsequent convergent deformation. Resume : Le cap Kiber sur la cote arctique de Chukotka, dans le nord-est de la Russie, est forme d'un granite qui penetre des strates datant du Devonien (et plus anciennes?) dans le creur d'un grand anticlinal a pendage vers le sud-est. Ces strates sont recouvertes de maniere structurale par des strates datant du Carbonifere et plus recentes. Un age, determine par U-Pb, de 351,4 ± 5,6 (2σ) Ma montre que le granite date du Carbonifere precoce. Un gros caillou de granite, extrait d'un conglomerat datant du Carbonifere, a donne un age U-Pb de Devonien tardif ou de Carbonifere precoce de ~355-361 Ma. De plus, un dyke de granite deforme et altere a donne un age de 363.7 ± 5.7 (2σ) Ma. Les elements majeurs et en trace suggerent un environnement de collision synchrone (orogenique). Le spectre du relachement d'Ar du granite (biotite) est reinitialise. Le dyke de granite montre aussi un spectre Ar-Ar perturbe de la roche entiere, ce qui signifierait un age Cretace precoce (environ 122-130 Ma) pour la fermeture du systeme Ar. Nous interpretons cela comme etant du a un metamorphisme au facies des schistes verts etendu qui accompagne la deformation regionale de la zone de plissements Anyuy-Chukotka, laquelle accompagne la fermeture de l'ocean Anyuy sud. A l'echelle regionale, cet evenement a eu lieu avant la deposition des strates aptiennes et albiennes et l'eruption des roches magmatiques d'Okhotsk-Chukotsk. Un age plateau de 96,4 ± 1,0 (2σ) Ma, determine par Ar-Ar (sur une biotite) d'un dyke de lamprophyre legerement deforme, correspond a une intrusion dans un environnement d'extension regionale. Sa deformation est le reflet d'un evenement tectonique plus jeune. L'enregistrement de magmatisme au Devonien-Carbonifere et le retrait du toit au Carbonifere precoce est plus recent et moins complexe que celui de l'Alaska arctique. Toutefois, les evidences pour une deformation au Devonien precoce (Caledonien) ou au Devonien tardif (Ellesmerien) pourraient avoir ete masquees par une deformation intense au Mesozoique. Les donnees provenant des affleurements et de la geochronologie supportent et peaufinent les interpretations regionales d'une deformation et d'une croissance mineralogique au Cretace precoce qui accompagnaient l'accretion de Chukotka a l'Asie septentrionale; cette accretion a ete suivie d'une extension regionale et d'une deformation subsequente de convergence. [Traduit par le Redaction], Introduction As part of the Canada-Russia Science and Technology Exchange Agreement, co-operative field projects were undertaken to clarify the distribution and correlation of circum-Arctic Phanerozoic strata. One project, in 1989, [...]

The Santa Catalina Mountains, SE Arizona, was one of the first metamorphic core complexes to be described. Despite its status as a type example, relatively little is known about precise ages and origins of the intrusive rocks that make up most of the crystalline core. U-Pb and Hf isotopic data by laser ablation-inductively coupled plasma-mass spectrometry from zircons and Nd isotopic results from whole rocks were obtained for 12 granitoids ranging from 1,440 to 26 Ma. Results confirm that the 1.44-Ga Oracle Granite extends through the Catalina Range as variably mylonitic granite and banded gneiss. Laramide intrusions (67-73 Ma) display initial [ζ.sub.Nd] values -5to -8 and [ζ.sub.Hf] from -7.5 to -9. Magmatic ages for the prominent white granite sills of the Wilderness suite are 46-57 Ma, in agreement with Terrien (2012), and these granites have initial [ζ.sub.Nd] values -8 to -10 and [ζ.sub.Hf] from -7 to -14. Lastly, the undeformed Catalina Granite has an age of 26 Ma, with an initial [ζ.sub.Nd] and [ζ.sub.Hf] of -6 and -8, respectively. Our Nd results agree with limited results from Farmer and DePaolo (89:10141-10160, 1984). Although the Catalina Granite seems to have a significant juvenile component based on Nd and Hf, most of the Laramide and Wilderness intrusions contain Nd and Hf compositions lying close to the evolution of 1.44-Ga Oracle Granites, a fact that is confirmed by the U-Pb data, which show both 1.7- and 1.4-Ga zircon cores in these samples, with 1.4 Ga as the dominant core age. In order to become the dominant source of most of the 72-45-Ma magmas, the Oracle pluton must not only extend across the whole Catalina region, but also have abundant deep-seated equivalents to provide magma sources. Keywords Santa Catalina metamorphic core complex * Granite origins * U-Pb ages * Hafnium isotopes * Neodymium isotopes, Introduction The Santa Catalina metamorphic core complex (Fig. 1), part of a chain of NW-trending metamorphic core complexes stretching across Arizona (Banks 1980; Davis 1980), is among the first occurrence [...]

U-Pb dating of 1035 detrital zircons from 12 spatially distributed samples of the Paleoproterozoic Vishnu Schist (Arizona, United States) reveals a bimodal [sup.207]pb/[sup.206]Pb age probability diagram with peaks at 1.8 Ga and 2.5 Ga. Surprisingly, only 13% of detrital zircon ages overlap with the published depositional age range of 1750-1741 Ma. The similarity of the age distributions in all samples constrains possible suturing of crustal blocks to pre-Vishnu Schist deposition rather than during the peak 1710-1680 Ma deformation. Of all grains analyzed, 15% overlap at 2[sigma] with the 1.84 [+ or -] 1 Ga Elves Chasm orthogneiss of the western Grand Canyon. This supports field evidence that the Vishnu Schist was deposited on 1.84 Ga arc basement rather than in a juvenile 1.75 Ga arc setting. Archean grains of 3.8-2.5 Ga compose 30% of all grains. A comparison of the ages older than 2.2 Ga from the Vishnu Schist (495 grains) with compilations of zircon ages from other cratons does not support provenances in the Wyoming, South China, or Siberian cratons; instead sources may be located in Gawler craton of Australia, North China craton, or Antarctica. If the detrital zircons were far-traveled, this is a new constraint for viable reconstructions of the Nuna supercontinent. However, given the high percentage of pre-1.8 Ga zircons, unexposed proximal basement sources are more likely, resulting in a model by which Vishnu sediments were derived from Mojave province crust that consists of Archean and 1.9-1.8 Ga crust, now in the subsurface, that was unroofed during Vishnu deposition. doi: 10.1130/G31335.1

[1] The stratigraphic record of Mesozoic arc accretion in the North American Cordillera is preserved in a discontinuous belt of clastic strata that are exposed inboard (cratonward) of the allochthonous Wrangellia composite terrane in southern Alaska, western Canada, and Washington State. LA-ICPMS analyses of eight samples (n = 714 detrital zircon grains) collected at different stratigraphic intervals from the Jurassic-Cretaceous Kahiltna assemblage in southern Alaska reveals a bulk U-Pb age distribution of Precambrian-Mesozoic age grains (Mz 74%, Pz 11%, Pc 15%). A comparison of U-Pb ages from older to younger stratigraphic intervals within the Kahiltna assemblage reveals three stages of exhumation and basin development during arc accretion. Stages include (1) an initial Late Jurassic-Early Cretaceous pre/early collisional phase during which detritus was derived almost solely from Middle-Late Jurassic and Early Cretaceous magmatic sources of the outboard Wrangellia composite terrane (Mz 100%, Pz 0%, Pc, 0%), (2) a second Early Cretaceous syncollisional phase that reflects the introduction of Paleozoic and Precambrian detritus from the inboard Intermontane belt (Mz 84%, Pz 11%, Pc 5%) and an upsection increase in older detrital zircon grains compared to Mesozoic age grains (Mz 65%, Pz 11%, Pc 24%), and (3) a final Early-Late Cretaceous late/postcollisional phase that represents continued detrital contributions from Precambrian-Mesozoic source areas (Mz 19%, Pz 22%, Pc 59%) located inboard and outboard of the Kahiltna basin. Similar bulk trends in detrital zircon age populations have been reported from along-strike, age-equivalent strata of the Gravina belt (Mz 74%, Pz 20%, Pc 6%) in southeastern Alaska suggesting that similar provenance trends may exist in basins along this >2000 km -long collisional zone. Citation: Hampton, B. A., K. D. Ridgway, and G. E. Gehrels (2010), A detrital record of Mesozoic island arc accretion and exhumation in the North American Cordillera: U-Pb geochronology of the Kahiltna basin, southern Alaska, Tectonics', 29, TC4015, doi: 10.1029/2009TC002544.

[1] The Sierra Valle Fertil Range in northwestern Argentina exposes a tilted crustal section through the Ordovician Famatinian arc, from >25 km to shallow crustal paleodepths. Fourteen new U-Pb zircon crystallization ages of magmatic rocks from Sierra Valle Fertil area show that this section of the arc was built over a short time interval during the Ordovician, between 485 and 465 Ma. Zircon rim ages demonstrate that high-grade metamorphism and migmatization were synchronous with magmatic emplacement. Inherited ages in some of the plutonic rocks as well as detrital zircons in the metasedimentary framework suggest that the Famatinian arc was emplaced into a thick miogeoclinal cover to the thinned margin of the proto-South American continent in the Ordovician, which represents a part of Gondwana. Docking of the Precordilleran terrane outboard of proto-South America led to the cessation of arc magmatism in the Valle Fertil area and preservation of the arc in its early stages after

The U-Pb age spectrum of detrital zircons in sandstone of the fluvial Middle Jurassic Ionia Formation in the Michigan basin, United States, resembles the age spectra in Jurassic eolianites of the Colorado Plateau, except that a Neoproterozoic (725-510 Ma) subpopulation present in the eolianites is absent from the Michigan basin strata. The detrital zircon data are compatible with the hypothesis that the Ionia Formation was deposited by northern tributaries of a transcontinental Jurassic paleoriver system that transported detritus from headwaters in Atlantic rift highlands of the Appalachian region to floodplains and deltas in the present northern Rocky Mountains region. Previous detritai zircon studies have indicated that sedimented lowlands in that paleogeographic position were deflated by paleowinds to feed eolian sand southward (in present coordinates) into the Colorado Plateau ergs (sand seas). doi: 10.1130/G30509.1

U-Pb detrital zircon (DZ) ages (n = 807) from Lower Cretaceous and lowermost Upper Cretaceous synorogenic conglomerate and interbedded sandstone deposited in and near the foredeep of the Cordilleran foreland basin in central Utah indicate stratigraphic compositional variation among the deposits. Eight DZ age populations, ranging from Archean through Mesozoic, are present in the synorogenic foredeep deposits in varying proportions and permit definition of three compositional suites, termed here chronofacies. Chronofacies A, present in uppermost Neocomian--lowermost Aptian foredeep deposits, contains Archean through early Paleozoic DZ grains derived from Jurassic--Pennsylvanian strata of the thrust belt. Chronofacies B, in Aptian--Albian foredeep deposits, contains Archean and Paleoproterozoic grains with an age peak near 1850 Ma, a population distribution similar to that of lower Paleozoic quartzites of the thrust belt. Chronofacies C, in Albian--lower Cenomanian foredeep deposits, contains a trimodal population distribution of Paleoproterozoic and Mesoproterozoic grains similar to that of Cambrian--Neoproterozoic quartzite strata of the thrust belt. The chronofacies of the foredeep deposits thus record systematic erosional unroofing of the thrust belt during Early Cretaceous time. doi: 10.1130/G30684.1