The Wyoming Province: a distinctive Archean craton in Laurentian North America

2006 ◽  
Vol 43 (10) ◽  
pp. 1391-1397 ◽  
Author(s):  
P A Mueller ◽  
C D Frost
Keyword(s):  
Detrital Zircon ◽  
Isotopic Signature ◽  
Crustal Growth ◽  
Continental Arc ◽  
Accreted Terranes ◽  
Wyoming Province ◽  
Detrital Zircon Ages ◽  
Terrane Accretion ◽  
Mafic Lower Crust ◽  
Continental Arc Magmatism

The Wyoming Province is a distinctive Archean craton in the northwestern United States that can be subdivided into three subprovinces, namely, from oldest to youngest, the Montana metasedimentary province, the Beartooth–Bighorn magmatic zone, and the Southern accreted terranes. Archean rocks of the Montana metasedimentary province and the Beartooth–Bighorn magmatic zone are characterized by (1) their antiquity (rock ages to 3.5 Ga, detrital zircon ages up to 4.0 Ga, and Nd model ages exceeding 4.0 Ga); (2) a distinctly enriched 207Pb/204Pb isotopic signature, which suggests that this part of the province was not produced by the amalgamation of exotic terranes; and (3) a distinctively thick (15–20 km), mafic lower crust. The Montana metasedimentary province and Beartooth–Bighorn magmatic zone were cratonized by about 3.0–2.8 Ga. Crustal growth occurred via continental-arc magmatism and terrane accretion in the Southern accreted terranes along the southern margin of the province at 2.68–2.50 Ga. By the end of the Archean, the three subprovinces were joined as part of what is now the Wyoming Province. Subsequent to amalgamation of the Wyoming crust to Laurentia at ca. 1.8–1.9 Ga, Paleoproterozoic crust (1.7–2.4 Ga) was juxtaposed along the southern and western boundaries of the province. Subsequent tectonism and magmatism in the Wyoming region are concentrated in the areas underlain by these Proterozoic mobile belts.

Detrital zircon geochronology of Neoproterozoic to Permian miogeoclinal strata in British Columbia and Alberta

1998 ◽  
Vol 35 (12) ◽  
pp. 1380-1401 ◽  
Author(s):  
George E Gehrels ◽  
Gerald M Ross
Keyword(s):  
British Columbia ◽  
Detrital Zircon ◽  
Isotopic Signature ◽  
Detrital Zircons ◽  
Detrital Zircon Geochronology ◽  
Salmon River ◽  
Western Canada Sedimentary Basin ◽  
Cordilleran Margin ◽  
Peace River Arch ◽  
Detrital Zircon Ages

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.

scholarly journals Igneous rock area and age in continental crust

Geology ◽  
2021 ◽  
Author(s):  
Shanan E. Peters ◽  
Craig R. Walton ◽  
Jon M. Husson ◽  
Daven P. Quinn ◽  
Oliver Shorttle ◽  
...  
Keyword(s):  
Continental Crust ◽  
Detrital Zircon ◽  
Igneous Rock ◽  
Source Rocks ◽  
Crustal Growth ◽  
Zircon Age ◽  
Frequency Distributions ◽  
Early Increase ◽  
Depositional Age ◽  
Detrital Zircon Ages

Rock quantity and age are fundamental features of Earth’s crust that pertain to many problems in geoscience. Here we combine new estimates of igneous rock area in continental crust from the Macrostrat database (https://macrostrat.org/) with a compilation of detrital zircon ages in order to investigate rock cycling and crustal growth. We find that there is little or no decrease in igneous rock area with increasing rock age. Instead, igneous rock area in North America exhibits four distinct Precambrian peaks, remains low through the Neoproterozoic, and then increases only modestly toward the recent. Peaks in Precambrian detrital zircon age frequency distributions align broadly with peaks in igneous rock area, regardless of grain depositional age. However, detrital zircon ages do underrepresent a Neoarchean peak in igneous rock area; young grains and ca. 1.1 Ga grains are also overrepresented relative to igneous area. Together, these results suggest that detrital zircon age distributions contain signatures of continental denudation and sedimentary cycling that are decoupled from the cycling of igneous source rocks. Models of continental crustal evolution that incorporate significant early increase in volume and increased sedimentation in the Phanerozoic are well supported by these data.

Styles of Proterozoic crustal growth on the southeast margin of Laurentia: evidence from the central Grenville Province northwest of Lac St.-Jean, Quebec

2005 ◽  
Vol 42 (10) ◽  
pp. 1643-1652 ◽  
Author(s):  
C Martin ◽  
A P Dickin
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Arc Magmatism ◽  
Crustal Growth ◽  
Grenville Province ◽  
Nd Isotope ◽  
Continental Arc ◽  
Wide Range ◽  
Western Block ◽  
Continental Arc Magmatism

The southeast margin of Laurentia was a very long lived active continental margin, part of whose history is recorded in the Grenville Province of the Canadian Shield. Within this province, Nd-isotope mapping can be used to define the boundaries between terranes with a variety of crustal formation ages and can also distinguish between crustal growth by oceanic and continental-arc magmatism. The former gives rise to large terranes with homogeneous Nd-isotope signatures and well-defined boundaries, whereas the latter leads to areas with heterogeneous Nd-isotope signatures. One of the best examples of continental-arc magmatism in the Grenville Province is provided by the region northwest of Lac St.-Jean, Quebec. Eighty new Nd-isotope analyses are used (along with aeromagnetic data) to divide this area into three blocks, bounded by abrupt changes in Nd model age. The western block consists almost exclusively of tonalitic grey gneisses with Archean model ages. The eastern block is composed almost exclusively of gneisses with Nd model ages of 1.6–1.5 Ga and tonalite–trondhjemite–granodiorite-type chemistry. In contrast, the central block has a wide range of Nd-isotope signatures and more alkaline major element chemistry characteristic of an ensialic arc. The εNd values in this block correlate with distance southeast of the Allochthon Boundary Thrust, suggesting that ensialic arc magmas suffered diminishing contamination in a southeastward direction by old Laurentian crust. A subduction-flip model is proposed, whereby north-dipping subduction under the continental margin followed the accretion of a Mesoproterozoic arc terrane to the Laurentian craton.

Archean crustal growth by lateral accretion of juvenile supracrustal belts in the south-central Wyoming Province

2006 ◽  
Vol 43 (10) ◽  
pp. 1533-1555 ◽  
Author(s):  
Carol D Frost ◽  
Benjamin L Fruchey ◽  
Kevin R Chamberlain ◽  
B Ronald Frost
Keyword(s):  
Plate Tectonics ◽  
Crustal Growth ◽  
Klamath Mountains ◽  
The South ◽  
Wind River Range ◽  
South Central ◽  
Metavolcanic Rocks ◽  
Wyoming Province ◽  
Terrane Accretion ◽  
Geologic Processes

Neoarchean supracrustal sequences in the south-central Wyoming Province are exposed as relatively small belts in Laramide uplifts. Some sequences are composed of materials derived mainly from pre-existing Wyoming province crust, but others are dominated by juvenile components. The latter include the Miners Delight Formation in the Wind River Range, the Rattlesnake Hills Group in the Granite Mountains, and the Bradley Peak succession in the Seminoe Mountains. U–Pb zircon dates from interbedded metavolcanic rocks suggest that these supracrustal belts are of at least two different ages: ca. 2.67 and ca. 2.72 Ga. We identify a time of contractional deformation and accretion of some of these supracrustal packages to the southern Wyoming Province at ~2.65–2.63 Ga. Magmatism is nearly synchronous with deformation. Some granitoids intrude the Wyoming Province basement, as well as the juvenile rocks thrust onto this basement; these have Nd isotopic compositions indicating that these plutons assimilated some old continental basement during ascent. Plutons intruding the supracrustal rocks located farther from the margin do not show this continental influence. The time scale and geologic processes of deposition, contractional deformation, and plutonism appear analogous to Phanerozoic examples of oceanic terrane accretion, such as formed the Klamath Mountains Province of California and Oregon. We conclude that a major episode of Neoarchean crustal growth involved both the lateral accretion of juvenile terranes and the intrusion of arc magmas formed from mantle-derived and (or) juvenile crustal sources and was driven by geologic processes very similar to modern plate tectonics.

DETRITAL ZIRCON AGES REVEAL POST 15 MA CONVERGENCE AND PLEISTOCENE-QUATERNARY BASEMENT UNROOFING IN THE CAUCASUS

2017 ◽  
Author(s):  
Alexander Tye ◽  
◽  
Nathan A. Niemi ◽  
Rafiq Safarov ◽  
Fakhraddin Kadirov
Keyword(s):  
Detrital Zircon ◽  
The Caucasus ◽  
Detrital Zircon Ages
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