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.

Caledonian terrane amalgamation of Svalbard: detrital zircon provenance of Mesoproterozoic to Carboniferous strata from Oscar II Land, western Spitsbergen

2013 ◽  
Vol 150 (6) ◽  
pp. 1103-1126 ◽  
Author(s):  
DETA GASSER ◽  
ARILD ANDRESEN
Keyword(s):  
Detrital Zircon ◽  
Large Scale ◽  
Strike Slip ◽  
Western Coast ◽  
Zircon Age ◽  
The North ◽  
Tectonic History ◽  
Icp Ms ◽  
Depositional Age ◽  
Sveconorwegian Orogen

AbstractThe tectonic origin of pre-Devonian rocks of Svalbard has long been a matter of debate. In particular, the origin and assemblage of pre-Devonian rocks of western Spitsbergen, including a blueschist-eclogite complex in Oscar II Land, are enigmatic. We present detrital zircon U–Pb LA-ICP-MS data from six Mesoproterozoic to Carboniferous samples and one U–Pb TIMS zircon age from an orthogneiss from Oscar II Land in order to discuss tectonic models for this region. Variable proportions of Palaeo- to Neoproterozoic detritus dominate the metasedimentary samples. The orthogneiss has an intrusion age of 927 ± 3 Ma. Comparison with detrital zircon age spectra from other units of similar depositional age within the North Atlantic region indicates that Oscar II Land experienced the following tectonic history: (1) the latest Mesoproterozoic sequence was part of a successor basin which originated close to the Grenvillian–Sveconorwegian orogen, and which was intruded byc. 980–920 Ma plutons; (2) the Neoproterozoic sediments were deposited in a large-scale basin which stretched along the Baltoscandian margin; (3) the eclogite-blueschist complex and the overlying Ordovician–Silurian sediments probably formed to the north of the Grampian/Taconian arc; (4) strike-slip movements assembled the western coast of Spitsbergen outside of, and prior to, the main Scandian collision; and (5) the remaining parts of Svalbard were assembled by strike-slip movements during the Devonian. Our study confirms previous models of complex Caledonian terrane amalgamation with contrasting tectonic histories for the different pre-Devonian terranes of Svalbard and particularly highlights the non-Laurentian origin of Oscar II Land.

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.

Detrital zircon age fingerprinting of NW and SW Iberia Variscan basins: Constraints for the pre-Pangea terrane assemblage analysis and paleogeography

2020 ◽  
Author(s):  
Ícaro Dias da Silva ◽  
Manuel Francisco Pereira ◽  
Emílio González Clavijo ◽  
José R. Martínez Catalán ◽  
Juan Gómez Barreiro ◽  
...  
Keyword(s):  
Statistical Analysis ◽  
Detrital Zircon ◽  
Sedimentary Basins ◽  
Zircon Age ◽  
Drainage Systems ◽  
Middle Ordovician ◽  
Source Areas ◽  
Provenance Studies ◽  
Sedimentary Environments ◽  
Nw Iberia

<p>Synorogenic basins could be linked to a wide variety of sedimentary environments, from continental to deep-marine, in distinct geodynamic settings. The sedimentary evolution of synorogenic basins is mainly controlled by the existence of relief rejuvenation and denudation within and in the surroundings areas. Accumulation of sediment in such basins could react to changes in tectonic settings. Successive extensional or contractional events that are common during the formation of an orogenic belt can induce variations on basin depth, basin depocenter migration and/or repetition of sedimentation-erosion cycles.</p><p>Detrital zircon age fingerprinting of sedimentary basins has proven to be a very sensitive tool for analyzing large and local scale changes in source-terranes, contributing to refine regional paleogeographic models. Recognition of potential source areas could be done by using statistically robust techniques. Kolmogorov-Smirnoff test (K-S) and Multidimensional Scaling (MDS) has been successfully applied to define the fingerprints of sedimentary rocks using detrital zircon age populations and compare with those from potential terrane sources. Comparative statistical analysis of detrital zircon age populations from particular sources and basin strata may be useful to prove sedimentary provenance and distance from source areas, to identify intra-basin sediment recycling and to track multi-source mixing along drainage systems.</p><p>During the Late Devonian-Carboniferous amalgamation of Pangea extensive marine sedimentation occurred in the Variscan orogen on both Laurussia and Gondwana collision margins. Remains of such synorogenic basins are currently located in different sectors of the European Variscan belt, including Iberia.</p><p>Recent provenance studies conducted in SW Iberia Variscan basins have distinguished the contribution of three distinct terrane sources “Gondwana-”, “Laurussia-” and “Variscan magmatic arc-” types, in some cases admitting sediment recycling and mixing of sources. Statistical analysis of detrital zircon age population from NW Iberia Variscan basin allowed us to distinguish two major sources a “Middle Ordovician-Silurian magmatic episode”-type and a “Gondwana”-type. These two types appear to correspond to source areas belonging to the nearby autochthonous and allochthonous units. Gondwanan-type source includes six sub-types whose contributions varied throughout synorogenic basins evolution, indicating that where sedimentary recycling seems to have been relevant.</p><p>Provenance studies on Variscan basins proved to be essential to test if whether or not NW Iberia and SW Iberia synorogenic basins have developed in geographical proximity of Paleozoic Laurussian- or Gondwanan-terrane sources. The differences found between the sources of NW and SW Variscan basins suggest that they would be geographically separated and influenced by independent drainage systems. This finding has provided a better understanding of the framing of Iberia synorogenic basins in paleographic models of Pangea amalgamation.</p><p>Acknowledgements: This study was supported by SYNTHESIS3 project DE-TAF-5798, by “Estímulo ao Emprego Científico – Norma Transitória” by CGL2016-78560-P (MICINN) and by FCT- project UID/GEO/50019/2019 - Instituto Dom Luiz.</p>

scholarly journals Revisiting the Intermediate Sediment Repository Concept Applied to the Provenance of Zircon

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 233
Author(s):  
Manuel Francisco Pereira ◽  
Cristina Gama
Keyword(s):  
Detrital Zircon ◽  
Age Distribution ◽  
Age Groups ◽  
Source Rocks ◽  
Beach Sand ◽  
Density Estimator ◽  
Zircon Age ◽  
Potential Source ◽  
Sedimentary System ◽  
Siliciclastic Rocks

This paper revisits the intermediate sediment repository (ISR) concept applied to provenance, using a comparison of the detrital zircon population of Holocene beach sand from the southwest Portuguese coast with populations from their potential source rocks. The U–Pb age of detrital zircon grains in siliciclastic rocks allows for the interpretation of provenance by matching them with the crystallization ages of igneous source (protosource) rocks in which this mineral originally crystallized or which was subsequently recycled from it, acting as ISRs. The comparative analysis of the Precambrian, Paleozoic, and Cretaceous ages using recent statistical tools (e.g., kernel density estimator (KDE), cumulative age distribution (CAD), and multidimensional scaling (MDS)) suggests that the zircon age groups of Carboniferous, Triassic, and Pliocene-Pleistocene ISRs are reproduced faithfully in Holocene sand. Furthermore, the recycling of a protosource (Cretaceous syenite) in a sedimentary system dominated by ISRs is evaluated. It is argued that the ISR concept, which is not always taken into account, is required for a better understanding of the inherent complexity of local provenance and to differentiate sediment recycling from first- cycle erosion of an igneous rock.

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

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.

Late Proterozoic arc–continent and continent–continent collision in the pan-African trans-Saharan belt of Mali

1989 ◽  
Vol 26 (6) ◽  
pp. 1136-1146 ◽  
Author(s):  
Renaud Caby ◽  
Uranie Andreopoulos-Renaud ◽  
Christian Pin
Keyword(s):  
Isotopic Composition ◽  
Sedimentary Rocks ◽  
Volcanic Arc ◽  
Zircon Age ◽  
Magmatic Source ◽  
Magmatic Arc ◽  
Isotopic Compositions ◽  
Pan African ◽  
Depleted Mantle ◽  
Grey Gneiss

The Tilemsi magmatic arc, preserved along the suture zone of the pan-African trans-Saharan belt of northern Mali, crops out as a series of northeast- to north-northeast-trending strips along the Tilemsi Mesozoic trough and is about 100 km in width. The volcanic arc series includes pillowed metabasalts of tholeiitic character and associated with rhyodacites. Overlying sedimentary rocks are turbiditic volcanic greywackes. They are progressively recrystallized into grey gneiss in the vicinity of gabbro-noritic and dioritic intrusions. U/Pb zircon dating of a crosscutting metaquartz diorite gives a nearly concordant age of [Formula: see text], while that of a plagiogranite mobilizate associated with the grey gneiss is [Formula: see text]. Initial Nd and Sr isotopic compositions of two metaquartz diorites (εNd730 = +6.6, +6.3; (87Sr/86Sr)i = 0.7024) are in a agreement with a depleted mantle source similar to modern intraoceanic arcs. Isotopic compositions of two Tilemsi metagreywackes (εNd730 = +5.8, +4.3; 87Sr/86Sr ≈ 0.7027) exclude any significant derivation from an older sialic source and support the ensimatic origin of the magmatic arc. A U/Pb zircon age of 635 ± 5 Ma has also been obtained on a pretectonic granodiorite batholith at the eastern margin of the arc. Isotopic composition of this intrusion (εNdi = −6.0, −6.4; (87Sr/86Sr)i = 0.7046) illustrates the lack of a genetic link between the 730 Ma old, mantle-derived magmas and these granitoids, which originated from a crustal reservoir. This change in magmatic source is interpreted as the result of accretion of the ensimatic arc along the eastern continent, preceding continent–continent collision during the pan-African event.

Detrital zircon ages and the origins of the Nashoba terrane and Merrimack belt in southeastern New England, USA

2021 ◽  
Vol 57 ◽  
pp. 343-396
Author(s):  
J. Christopher Hepburn ◽  
Yvette D. Kuiper ◽  
Kristin J. McClary ◽  
MaryEllen L. Loan ◽  
Michael Tubrett ◽  
...  
Keyword(s):  
New England ◽  
Detrital Zircon ◽  
Inductively Coupled Plasma ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Mass Spectrometry Analysis ◽  
Zircon Age ◽  
Spectrometry Analysis ◽  
Middle Ordovician ◽  
Nashoba Terrane

The fault-bounded Nashoba–Putnam terrane, a metamorphosed early Paleozoic, Ganderian arc/back-arc complex in SE New England, lies between rocks of Avalonian affinity to the southeast and middle Paleozoic sedimentary rocks, interpreted as cover on Ganderian basement, in the Merrimack belt to the northwest. U–Pb detrital zircon laser ablation inductively coupled plasma mass spectrometry analysis were conduced on six samples from the Nashoba terrane in Massachusetts and seven samples associated with the Merrimack belt in Massachusetts and SE New Hampshire to investigate their depositional ages and provenance. Samples from the Nashoba terrane yielded major age populations between ~560 and ~540 Ma, consistent with input from local sources formed during the Ediacaran–Cambrian Penobscot orogenic cycle and its basement rocks. Youngest detrital zircons in the terrane, however, are as young as the Early to Middle Ordovician. Six formations from the Merrimack belt were deposited between ~435 and 420 Ma based on youngest zircon age populations and crosscutting plutons, and yielded large ~470–443 Ma age populations. Three of these formations show only Gondwanan provenance. Three others have a mixed Gondwanan-Laurentian signal, which is known to be typical for younger and/or more westerly sedimentary rocks and may indicate that they are the youngest deposits in the Merrimack belt (late Silurian to early Devonian) and/or have been deposited in the equivalent of the more westerly Central Maine basin. Detrital zircon age populations from the Tower Hill Formation, along the faulted contact between the Merrimack belt and Nashoba terrane, are different from either of these tectonic domains and may indicate that the boundary is complex.

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