Detrital zircon geochronology of metasedimentary rocks in the southern Omineca Belt, Canadian Cordillera

1991 ◽  
Vol 28 (8) ◽  
pp. 1254-1270 ◽  
Author(s):  
Gerald M. Ross ◽  
Randall R. Parrish

We address two problems of Cordilleran geology in this study using U–Pb dating of single detrital zircon grains from metasedimentary rocks: the provenance of the Windermere Supergroup, and the age and correlation of metasedimentary rocks within the Shuswap Complex that are at high metamorphic grade. Because some of these rocks are clearly of North American affinity, the ages of zircons provide indirect constraints on the age and distribution of continental basement from which the zircons were derived.A consistent pattern emerges from ages of about 50 grains from six rocks. Nearly all samples analyzed (48–53°N) are characterized by a bimodal distribution of zircon ages of 1.65–2.16 Ga and > 2.5 Ga, with a distinct lack of ages between 2.1 and 2.5 Ga. Exceptions to this pattern are young zircons from two samples, from Valhalla and Grand Forks – Kettle complexes of southeastern British Columbia, that have grains 1435 ± 35 and 650 ± 15 Ma, respectively. These younger grains are inferred to have been derived from magmatic rocks, and they have no obvious source in either the Canadian Shield or the Alberta subsurface basement to the east. The Early Proterozoic and Archean ages of detrital zircons resemble those of dated basement rocks beneath the Alberta Basin as well as basement exposed within the Cordilleran hinterland (gneisses of Thor–Odin, Frenchman Cap, and Malton regions). However, 2.1–2.4 Ga rocks that are extensive in the subsurface of northern Alberta are not represented in the inventory of detrital zircon ages presented in this paper.This pattern suggests that much of the Cordilleran basement between these latitudes is underlain by Archean crust of the Hearne–Wyoming provinces that may be mantled to the west by an orogenic–magmatic belt of Early Proterozoic (1.7–1.9 Ga) age which may largely have been parallel to the present Cordilleran orogen.

1998 ◽  
Vol 35 (12) ◽  
pp. 1380-1401 ◽  
Author(s):  
George E Gehrels ◽  
Gerald M Ross

U-Pb ages have been determined on 250 detrital zircon grains from Neoproterozoic through Permian miogeoclinal strata in British Columbia and Alberta. Most of the grains in these strata are >1.75 Ga and are interpreted to have been derived from nearby basement provinces (although most grains were probably cycled though one or more sedimentary units prior to final deposition). Important exceptions are Ordovician sandstones that contain grains derived from the Peace River arch, and upper Paleozoic strata with detrital zircons derived from the Franklinian orogen, Salmon River arch (northwestern U.S.A.), and (or) Grenville orogen. These provenance changes resulted in average detrital zircon ages that become progressively younger with time, and may also be reflected by previously reported shifts in the Nd isotopic signature of miogeoclinal strata. In addition to the grains that have identifiable sources, grains of ~1030, ~1053, 1750-1774, and 2344-2464 Ma are common in our samples, but igneous rocks of these ages have not been recognized in the western Canadian Shield. We speculate that unrecognized plutons of these ages may be present beneath strata of the western Canada sedimentary basin. Collectively, our data provide a record of the ages of detrital zircons that accumulated along the Canadian Cordilleran margin during much of Paleozoic time. Comparisons between this reference and the ages of detrital zircons in strata of potentially displaced outboard terranes may help reconstruct the paleogeography and accretionary history of the Cordilleran orogen.


2019 ◽  
Vol 70 (4) ◽  
pp. 298-310
Author(s):  
Anna Vozárová ◽  
Nickolay Rodionov ◽  
Katarína Šarinová

Abstract U–Pb (SHRIMP) detrital zircon ages from the Early Paleozoic meta-sedimentary rocks of the Northern Gemericum Unit (the Smrečinka Formation) were used to characterize their provenance. The aim was to compare and reconcile new analyses with previously published data. The detrital zircon age spectrum demonstrates two prominent populations, the first, Late Neoproterozoic (545–640 Ma) and the second, Paleoproterozoic (1.8–2.1 Ga), with a minor Archean population (2.5–3.4 Ga). The documented zircon ages reflect derivation of the studied metasedimentary rocks from the Cadomian arc, which was located along the West African Craton. The acquired data supports close relations of the Northern Gemericum basement with the Armorican terranes during Neoproterozoic and Ordovician times and also a close palinspastic relation with the other crystalline basements of the Central Western Carpathians. In comparison, the detrital zircons from the Southern Gemericum basement and its Permian envelope indicate derivation from the Pan-African Belt–Saharan Metacraton provenance.


2017 ◽  
Vol 54 (2) ◽  
pp. 86-103 ◽  
Author(s):  
David Malone ◽  
John Craddock ◽  
Stuart Kenderes

We report the results of analyses of detrital zircon from the middle Cambrian Flathead Sandstone from four locations in Park County, WY. The Flathead U-Pb zircon age spectra (n=355) includes one peak at 2702–3345 Ma (95%) and two small age peaks at 1784 Ma (4%) and ∼1830 Ma (1%). Regional paleocurrent data for the Flat-head indicate sediment transport from east to west but the dominant Archean detrital zircons in our sample suite indicates a proximal source in structurally and topographically high Wyoming Province crust. The Archean ages are consistent with the >3.0 Ga fraction being derived from basement rocks present in the northern Beartooth Range and areas further to the west. The 2.8–3.0 Ga grains were derived from the Beartooth-Bighorn magmatic zone, which directly underlies and extends to the south and east of these Flathead sampling localities. The 1.7–1.8 Ga grains were derived from 100s of km to the south and east, in the Cheyenne Belt or more distal Yavapai Province rocks. This 1.7–1.8 Ga crust was uplifted along the Transcontinental Arch during late Precambrian time. The Transcontinental Arch, and perhaps the Midcontinent Rift further to the east as well, prevented easterly-sourced (i.e. Grenville) zircons from reaching the Wyoming Sauk shoreline.


2013 ◽  
Vol 50 (10) ◽  
pp. 1007-1018 ◽  
Author(s):  
Luke P. Beranek ◽  
Victoria Pease ◽  
Robert A. Scott ◽  
Tonny B. Thomsen

Enigmatic successions of deep-water strata referred to as the Nesmith beds and Grant Land Formation comprise the exposed base of the Franklinian passive margin sequence in northern Ellesmere Island, Nunavut. To test stratigraphic correlations with Ediacaran to Cambrian shallow-water strata of the Franklinian platform that are inferred by regional basin models, >500 detrital zircons from the Nesmith beds and Grant Land Formation were analyzed for sediment provenance analysis using laser ablation (LA–ICP–MS) and ion-microprobe (SIMS) methods. Samples of the Nesmith beds and Grant Land Formation are characterized by 1000–1300, 1600–2000, and 2500–2800 Ma detrital zircon age distributions and indicate provenance from rock assemblages of the Laurentian craton. In combination with regional stratigraphic constraints, these data support an Ediacaran to Cambrian paleodrainage model that features the Nesmith beds and Grant Land Formation as the offshore marine parts of a north- to northeast-directed depositional network. Proposed stratigraphic correlations between the Nesmith beds and Ediacaran platformal units of northern Greenland are consistent with the new detrital zircon results. Cambrian stratigraphic correlations within northern Ellesmere Island are permissive, but require further investigation because the Grant Land Formation provenance signatures agree with a third-order sedimentary system that has been homogenized by longshore current or gravity-flow processes, whereas coeval shallow-water strata yield a restricted range of detrital zircon ages and imply sources from local drainage areas or underlying rock units. The detrital zircon signatures of the Franklinian passive margin resemble those for the Cordilleran and Appalachian passive margins of Laurentia, which demonstrates the widespread recycling of North American rock assemblages after late Neoproterozoic continental rifting and breakup of supercontinent Rodinia.


Geosphere ◽  
2019 ◽  
Vol 15 (4) ◽  
pp. 1102-1127 ◽  
Author(s):  
William A. Thomas ◽  
George E. Gehrels ◽  
Timothy F. Lawton ◽  
Joseph I. Satterfield ◽  
Mariah C. Romero ◽  
...  

AbstractNew analyses of U-Pb ages along with previously published analyses of detrital zircons from sandstones in the foreland of the Marathon orogen in west Texas have significant implications regarding provenance. The most prominent concentrations of U-Pb ages are at 1200–1000, 700–500, and 500–290 Ma. The accreted Coahuila terrane in the Marathon hinterland and nearby terranes with Gondwanan (Amazonia) affinity include Paleozoic volcanic and plutonic rocks, as well as Precambrian basement rocks. Late Paleozoic Las Delicias arc rocks have ages of 331–270 Ma. Detrital zircons from Upper Jurassic and Lower Cretaceous sandstones, which were deposited in local basins around the Coahuila terrane, provide a record of detritus available from proximal sources within Coahuila, including important peaks at 1040, 562, 422, 414, 373, and 282 Ma. Components of the detrital-zircon populations in the Marathon foreland have unique matches with primary and/or detrital sources in the Coahuila terrane. Although some components of the Marathon populations also have age matches in Laurentia (Appalachians), others do not; however, all components of the Marathon populations have potential sources in Coahuila. Analyses of εHft show generally more negative values in Amazonia than in Laurentia, and εHft values for Marathon sandstones have distributions similar to those in Amazonia. Therefore, the Coahuila terrane provides a provenance for all of the detrital-zircon ages in the Marathon foreland, requiring no mixing from other sources.


Minerals ◽  
2020 ◽  
Vol 10 (9) ◽  
pp. 786
Author(s):  
Annamaria Fornelli ◽  
Salvatore Gallicchio ◽  
Francesca Micheletti ◽  
Antonio Langone

U-Pb spot ages have been determined on detrital zircons from two samples of volcaniclastic arenites belonging to the Tufiti di Tusa Formation (TTF) outcropping in the Lucanian Apennines (Southern Italy). Many petrographic and geochemical studies have been performed on these sandstones with the aim of defining their detritus source. A new and precise evaluation of the mineralogical composition of metamorphic lithic fragments, together with U-Pb detrital zircon ages, helps to clarify the deposition age of these syn-sedimentary volcaniclastic sandstones and constrains their source areas. Volcaniclastic arenites consist of andesitic fragments and single minerals of plagioclases, clinopyroxenes, and hornblendes, while the metamorphic lithics are mainly fragments of blue amphibole-bearing micaschists, serpentinites, ophicalcites, phyllites, and medium-grade micaschists. Phaneritic plutonic fragments consist of quartz, feldspar, and micas. Carbonate components include biomicritic and biosparitic fragments. Eighty age data collected from 56 zircons reveal a wide age spectrum, ranging from Neoarchean to Rupelian (from 2712 ± 25 to 30 ± 1 Millions of years (Ma)). The age data show that in volcaniclastic sandstones there is evidence of ancient crystalline basements involved in Cadomian and Variscan orogenesis (ages from 2712 ± 25 Ma to ≈260 Ma), whereas the measured ages of 157 Ma testify the events of Pangea fragmentation and the ages between 78 and 67 Ma are related to subduction metamorphism connected to the Alpine orogenesis. Fifty percent of the estimated detrital zircon ages show a mean concordant age of 33 ± 1 Ma, they have been measured on idiomorphic crystals with undisturbed magmatic oscillatory zoning. These data reveal the true sedimentation age of Tufiti di Tusa sandstones at least at the sampled levels, coeval with that recorded in other Rupelian volcaniclastic successions outcropping in the Northern Apennines and in the Western Alps (e.g., Val d’Aveto-Petrignacola Formation, Ranzano Formation and Taveyannaz Sandstone). These data represent preliminary suggestions of the sedimentation age of the Tufiti di Tusa Formation and Rupelian paleogeography in the Western Mediterranean area. During Priabonian-Rupelian times, the volcanic calc-alkaline detritus linked to a widespread syn-sedimentary igneous activity on the hinterland terranes of the foredeep basins in the Apennine-Maghrebian orogen extended from north to south in the Western-Central Mediterranean area.


2010 ◽  
Vol 47 (11) ◽  
pp. 1383-1404 ◽  
Author(s):  
Reed S. Lewis ◽  
Jeffrey D. Vervoort ◽  
Russell F. Burmester ◽  
Peter J. Oswald

The authors analyzed detrital zircon grains from 10 metasedimentary rock samples of the Priest River complex and three other amphibolite-facies metamorphic sequences in north-central Idaho to test the previous assignment of these rocks to the Mesoproterozoic Belt–Purcell Supergroup. Zircon grains from two samples of the Prichard Formation (lower Belt) and one sample of Cambrian quartzite were also analyzed as controls with known depositional ages. U–Pb zircon analysis by laser ablation — inductively coupled plasma — mass spectrometry reveals that 6 of the 10 samples contain multiple age populations between 1900 and 1400 Ma and a scatter of older ages, similar to results reported from the Belt–Purcell Supergroup to the north and east. Results from the Priest River metamorphic complex confirm previous correlations with the Prichard Formation. Samples from the Golden and Elk City sequences have significant numbers of 1500–1380 Ma grains, which indicates that they do not predate the Belt. Rather, they are probably from a relatively young, southwestern part of the Belt Supergroup (Lemhi subbasin). Non-North American (1610–1490 Ma) grains are rare in these rocks. Three samples of quartzite from the Syringa metamorphic sequence northwest of the Idaho batholith contain zircon grains younger than the Belt Supergroup and support a Neoproterozoic age. A single Cambrian sample has abundant 1780 Ma grains and none younger than ∼1750 Ma. These results indicate that the likely protoliths of many high-grade metamorphic rocks in northern Idaho were strata of the Belt–Purcell Supergroup or overlying rocks of the Neoproterozoic Windermere Supergroup and not basement rocks.


1998 ◽  
Vol 35 (3) ◽  
pp. 269-279 ◽  
Author(s):  
G E Gehrels ◽  
P A Kapp

U-Pb ages have been determined for 55 detrital zircon grains from a metasedimentary sequence along the west flank of the Coast Mountains in southeastern Alaska. These rocks belong to the Port Houghton assemblage, which consists of upper Paleozoic pelitic and psammitic schist, metaconglomerate, metabasalt, and marble. The Port Houghton assemblage rests unconformably(?) on metamorphosed and deformed mid-Paleozoic arc-type volcanics (Endicott Arm assemblage), which gradationally overlie upper Proterozoic(?) - lower Paleozoic continental margin strata (Tracy Arm assemblage). Three main clusters of ages are present: 330-365 Ma (19 grains), 1710-2000 Ma (27 grains), and 2450-2680 Ma (6 grains). Additional grains are approximately 2334, 2364, and 3324 Ma. Comparison of these ages with detrital zircon ages in other Cordilleran assemblages supports previous interpretations that metasedimentary rocks in the Coast Mountains (i) form a southwestern continuation of the Yukon-Tanana terrane of eastern Alaska and Yukon, (ii) are not correlative with strata of the Alexander terrane, and (iii) contain detritus that was probably shed from cratonal rocks in the Canadian Shield to the east. Several scenarios exist to explain the occurrence of these continental margin rocks west (outboard) of arc-type and ocean-floor assemblages such as the Stikine, Cache Creek, Quesnel, and Slide Mountain terranes.


2017 ◽  
Vol 54 (2) ◽  
pp. 53-68 ◽  
Author(s):  
David Malone ◽  
John Craddock ◽  
Eric Deck ◽  
Tenley Banik ◽  
Brian Hampton

More than 2500 m of Paleozoic strata, ranging in age from Cambrian to Permian occur in the Sacramento Mountains of New Mexico, making these rocks the largest and most complete exposures of Paleozoic strata in North America. The core of the Sacramento Mountains reveals compressional structures associated with the Pennsylvanian-Permian Ancestral Rocky Mountain orogeny. The Permian Abo Formation is 120–450 m in thickness, and consists of interbedded sandstone, conglomerate, limestone and shale and rests above the Ancestral Rocky Mountain unconformity. U-Pb analysis of detrital zircons extracted from quartzite clasts in basal conglomerates reveal a maximum depositional age of their protolith to be 1110 ± 15 Ma. Most (∼40%) of the detrital zircon age spectrum is Grenville (1000–1300 Ma) in age, with a peak age of 1209 Ma. Midcontinent Granite-Rhyolite (1300–1500 Ma) ages comprise about 33% of the data, and have a peak age of 1431 Ma. Smaller age populations of Yavapai-Mazatzal (1600–1800 Ma; age peak =1676 Ma), Trans-Hudson (1800–2000 Ma; peak age = 1820 Ma), and Archean (>2.5 Ga, age peak = 2819 Ma) also are present. U-Pb detrital zircon ages from these quartzite clasts indicate that they were likely derived from the Proterozoic Lanoria Formation, which is exposed now in the Franklin Mountains >150 km to the south. The Lanoria is identical to the Abo clasts in terms of maximum depositional age and detrital zircon age peaks. The protolith sandstone of these quartzite clasts and quartzites of the Lanoria were derived from the Grenville high-lands of the Llano region of central Texas, and then transported west to the Rodinian continental margin at ∼1110 Ma, where they were eventually buried and metamorphosed to quartzite. These quartzites were subsequently uplifted and eroded during the Ancestral Rocky Mountain orogeny and transported north and west along the Pedernal Uplift to the adjacent Orogrande Basin during the early Permian.


Sign in / Sign up

Export Citation Format

Share Document