scholarly journals Zircon age constraints on the provenance of Llandovery to Wenlock sandstones from the Midland Valley terrane of the Scottish Caledonides

2009 ◽  
Vol 45 (2) ◽  
pp. 131-146 ◽  
Author(s):  
E. R. Phillips ◽  
R. A. Smith ◽  
P. Stone ◽  
V. Pashley ◽  
M. Horstwood
Keyword(s):  
Detrital Zircon ◽  
Sedimentary Rocks ◽  
Sedimentary Facies ◽  
Volcanic Arc ◽  
Zircon Age ◽  
Early Devonian ◽  
Southern Side ◽  
Lower Palaeozoic ◽  
Metamorphic Terrane ◽  
Age Constraints

SynopsisDetrital zircon populations within the Llandovery to Wenlock sandstones of the southern Midland Valley of Scotland indicate that the recycled orogenic provenance for these sedimentary rocks was essentially bimodal, comprising a younger Lower Palaeozoic component and an older predominantly Mesoproterozoic component. The Lower Palaeozoic contribution is dominated by Arenig/Llanvirn (c. 475 Ma) zircons interpreted as having been derived from a volcanic-plutonic source located within the Midland Valley terrane. The dominant Mesoproterozoic component within the sandstones is c. 1000 Ma and is thought to represent detritus shed from a Grenvillian (c. 1000–1800Ma) basement to the Midland Valley terrane. The scarcity of Archaean zircons precludes the Grampian metamorphic terrane Dalradian Supergroup as a supplier of sediment to the Ordovician–Silurian basins located along the southern margin of the Midland Valley. The age profiles of detrital zircon populations do not fit with a simple model of unroofing of a volcanic-arc complex. Rather they point to the periodic uplift of fault-bound, dismembered blocks of volcanic and plutonic rocks during a prolonged (Llandovery through to at least early Devonian) period of sinistral strike-slip deformation, and it was this which controlled basin development, sedimentary facies distribution and deformation along the southern side of the Midland Valley terrane.Appendices 1 & 2 can be found at http://www.geolsoc.org.uk/SUP18370

Enigmatic provenance signature of sandstone from the Okwa Group, Botswana

2020 ◽  
Vol 123 (3) ◽  
pp. 331-342
Author(s):  
T. Andersen ◽  
M.A. Elburg ◽  
J. Lehmann
Keyword(s):  
South Africa ◽  
Detrital Zircon ◽  
Sedimentary Rock ◽  
Age Distribution ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Significant Shift ◽  
Zircon Age ◽  
Three Samples ◽  
Isotope Distributions

Abstract Detrital zircon grains from three samples of sandstone from the Tswaane Formation of the Okwa Group of Botswana have been dated by U-Pb and analysed for Hf isotopes by multicollector LA-ICPMS. The detrital zircon age distribution pattern of the detrital zircons is dominated by a mid-Palaeoproterozoic age fraction (2 000 to 2 150 Ma) with minor late Archaean – early Palaeoproterozoic fractions. The 2 000 to 2 150 Ma zircon grains show a range of epsilon Hf from -12 to 0. The observed age and Hf isotope distributions overlap closely with those of sandstones of the Palaeoproterozoic Waterberg Group and Keis Supergroup of South Africa, but are very different from Neoproterozoic deposits in the region, and from the Takatswaane siltstone of the Okwa Group, all of which are dominated by detrital zircon grains younger than 1 950 Ma. The detrital zircon data indicate that the sources of Tswaane Formation sandstones were either Palaeoproterozoic rocks in the basement of the Kaapvaal Craton, or recycled Palaeoproterozoic sedimentary rocks similar to the Waterberg, Elim or Olifantshoek groups of South Africa. This implies a significant shift in provenance regime between the deposition of the Takatswaane and Tswaane formations. However, the detrital zircon data are also compatible with a completely different scenario in which the Tswaane Formation consists of Palaeoproterozoic sedimentary rock in tectonic rather than depositional contact with the other units of the Okwa Group.

scholarly journals Amazonian Mesoproterozoic basement in the core of the Ibero-Armorican Arc: 40Ar/39Ar detrital mica ages complement the zircon's tale

Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 637-640 ◽  
Author(s):  
G. Gutiérrez-Alonso ◽  
J. Fernández-Suárez ◽  
Alan S. Collins ◽  
I. Abad ◽  
F. Nieto
Keyword(s):  
Detrital Zircon ◽  
Sedimentary Rocks ◽  
Age Groups ◽  
Strike Slip ◽  
Zircon Age ◽  
Provenance Studies ◽  
The Core ◽  
Pan African ◽  
Rio Negro ◽  
Northwest Iberia

Abstract The 40Ar/39Ar age data on single detrital muscovite grains complement U-Pb zircon ages in provenance studies, as micas are mostly derived from proximal sources and record low-temperature processes. Ediacaran and Cambrian sedimentary rocks from northwest Iberia contain unmetamorphosed detrital micas whose 40Ar/39Ar age spectra suggest an Amazonian–Middle American provenance. The Ediacaran sample contained only Neoproterozoic micas (590–783 Ma), whereas the Cambrian sample contained three age groups: Neoproterozoic (550–640 Ma, Avalonian–Cadomian–Pan African), Mesoproterozoic- Neoproterozoic boundary (ca. 920–1060 Ma, Grenvillian-Sunsas), and late Paleoproterozoic (ca. 1580–1780 Ma, Rio Negro). Comparison of 40Ar/39Ar muscovite ages with published detrital zircon age data from the same formations supports the hypothesis that the Neoproterozoic basins of northwest Iberia were located in a peri-Amazonian realm, where the sedimentary input was dominated by local periarc sources. Tectonic slivering and strike-slip transport along the northern Gondwanan margin affected both the basins and fragments of basement that were transferred from Amazonian to northern African realms during the latest Neoproterozoic–earliest Cambrian. Exhumation and erosion of these basement sources caused shedding of detritus to the Cambrian basins, in addition to detritus sourced in the continental mainland. The apparent dominance of Rio Negro–aged micas in the Cambrian sandstone suggests the presence of unexposed basement of that age beneath the core of the Ibero-Armorican Arc.

scholarly journals Detrital zircon age constraints on basement history on the margins of the northern Rockall Basin

2014 ◽  
Vol 397 (1) ◽  
pp. 209-223 ◽  
Author(s):  
Andrew Morton ◽  
Dirk Frei ◽  
Martyn Stoker ◽  
David Ellis
Keyword(s):  
Detrital Zircon ◽  
Zircon Age ◽  
Age Constraints

Detrital zircon age constraints for the Winton Formation, Queensland: Contextualizing Australia's Late Cretaceous dinosaur faunas

2013 ◽  
Vol 24 (2) ◽  
pp. 767-779 ◽  
Author(s):  
Ryan T. Tucker ◽  
Eric M. Roberts ◽  
Yi Hu ◽  
Anthony I.S. Kemp ◽  
Steven W. Salisbury
Keyword(s):  
Late Cretaceous ◽  
Detrital Zircon ◽  
Zircon Age ◽  
Age Constraints

scholarly journals Detrital zircon age constraints on the provenance of sandstones on Hatton Bank and Edoras Bank, NE Atlantic

2009 ◽  
Vol 166 (1) ◽  
pp. 137-146 ◽  
Author(s):  
Andrew C. Morton ◽  
Kenneth Hitchen ◽  
C. Mark Fanning ◽  
Greg Yaxley ◽  
Howard Johnson ◽  
...  
Keyword(s):  
Detrital Zircon ◽  
Ne Atlantic ◽  
Zircon Age ◽  
Age Constraints

Persistence of Grenvillian dominance in Laurentian detrital zircon age systematics explained by sedimentary recycling: Evidence from detrital zircon double dating and detrital monazite textures and geochronology

Geology ◽  
2020 ◽  
Vol 48 (8) ◽  
pp. 792-797
Author(s):  
S.C. Zotto ◽  
D.P. Moecher ◽  
N.A. Niemi ◽  
J.R. Thigpen ◽  
S.D. Samson
Keyword(s):  
United States ◽  
Detrital Zircon ◽  
Source Region ◽  
Regional Metamorphism ◽  
Sedimentary Rocks ◽  
Eastern United States ◽  
Zircon Age ◽  
Lag Times ◽  
Definition Of ◽  
Geological Constraints

Abstract Grenvillian ages dominate Neoproterozoic to Paleozoic detrital zircon (DZ) populations across eastern Laurentia and persist through the present. The persistence of this dominance is inferred to result from recycling of DZ grains ultimately sourced from exceptionally Zr-rich and zircon-fertile Grenvillian granitoids. Pennsylvanian arenites of the Appalachian Basin (eastern United States) exhibit DZ U-Pb age distributions that are nearly identical to those of Neoproterozoic to Cambrian strata, and contain detrital diagenetic monazite grains formed via metamorphism or diagenesis of sedimentary rocks in the source region. Detrital zircon (U-Th)/He ages are mostly 475–300 Ma, yielding lag times [Δt = U-Pb age − (U-Th)/He age] of 500–1000 m.y. and 1200–2400 m.y. for Grenvillian and Paleoproterozoic to Archean DZ grains, respectively. Detrital monazite Th-Pb ages are comparable to (U-Th)/He cooling ages, reflecting formation of monazite during Paleozoic regional metamorphism of Neoproterozoic to Cambrian strata that reset the (U-Th)/He systematics of Grenvillian DZ grains within those metasediments. These results are either consistent with or prove recycling. Incorporation of other geological constraints permits definition of at least three (and potentially five) recycling events and their timing following initial post-Grenvillian exhumation and erosion (the “great Grenvillian sedimentation episode”). Recycling events include dispersal of post-Grenvillian sediment during deposition of Neoproterozoic to Cambrian strata (formation of the “Great Unconformity”: cycle 1), subsequent erosion of metamorphosed Neoproterozoic to Cambrian strata generating detritus for the Pennsylvanian arenites sampled here (cycle 2), and modern erosion of those arenites (cycle 3). Pancontinental river systems facilitated dispersal of sediment of ultimate Grenvillian age during or after each cycle.

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