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

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.

2017 ◽  
Vol 54 (2) ◽  
pp. 104-124 ◽  
Author(s):  
David Malone ◽  
John Craddock ◽  
Jessica Welch ◽  
Brady Foreman

We report the results of U-Pb ages from detrital zircon populations in the lower Eocene synorogenic Willwood Formation in the northern Absaroka Basin, Wyoming. Zircons (n=229) were extracted from three sandstone beds and one ash layer in the Willwood Formation at the base of Jim Mountain in the North Fork Shoshone River Valley. K-S statistical analysis indicates that the three sandstones, which were sampled from the base, middle, and top of the formation, have identical age spectra, indicating that the sandstone provenance remained the same during the duration of Willwood deposition. The zircon age spectra are dominated by Archean zircons (61%), with peak ages at 3270 and 2770 Ma. These sandstones also have very early Paleoproterozoic zircons (∼2450 Ma), which likely were derived from the Tobacco Root Mountains. The final significant age peak is ∼70 Ma, which is likely associated with the Cretaceous Tobacco Root batholith. The Jim Mountain ash, which occurs at the top of the succession, just beneath the allocthonous volcanic rocks of the Heart Mountain slide, has a maximum depositional age of ∼50 Ma. Between 49–50 Ma, as Eocene volcanism in the northern Absaroka Range became more prominent, stratovolcanoes grew and disrupted sediment transport into the Absaroka basin. Lower Wapiti sandstones to the southwest show a mix of Eocene, recycled Proterozoic and Archean grains. The coeval Crandall Conglomerate, which was dismembered by the emplacement of the Heart Mountain slide in the northern Absaroka Range, has a distinct detrital zircon age spectrum. Thus these stream systems that deposited the Crandall did not share the headwaters with the streams that supplied sediment to the Absaroka basin.


2011 ◽  
Vol 62 (4) ◽  
pp. 299-307 ◽  
Author(s):  
Ion Balintoni ◽  
Constantin Balica ◽  
Antoneta Seghedi ◽  
Mihai Ducea

Peri-Amazonian provenance of the Central Dobrogea terrane (Romania) attested by U/Pb detrital zircon age patterns The Central Dobrogea Shield is a part of the Moesia, a Paleozoic composite terrane located southward of the North Dobrogea Alpine orogen. The two geological units are separated from each other by a trans-lithospheric discontinuity, the Peceneaga-Camena transform fault. Along this fault, remnants of a Variscan orogen (i.e. North Dobrogea), recycled during the Alpine orogeny come in contact with two lithological entities of the Central Dobrogea Shield, unaffected by the Phanerozoic orogenic events: the Histria Formation, a flysch-like sequence of Ediacaran age very low-grade metamorphosed and its basement, the medium-grade metamorphosed Altîn Tepe sequence. Southward, along the reverse hidden Palazu fault, the Histria Formation meets South Dobrogea, formed of quite different geological formations. Detrital zircon from the Histria Formation yielded U/Pb LA ICP MS ages that show provenance patterns typical of peri-Amazonian terranes. Such terranes were sourced by orogens ranging from Paleoarchean to Neoproterozoic. The ages between 750 and 600 Ma differentiate the Amazonian sources from the Baltican and Laurentian sources, since they are lacking from the last ones. The youngest ages of 587 and 584 Ma suggest for the Histria Formation a maximum late Ediacaran deposition age. At the same time, the continuity of the Ordovician sediments over the Palazu fault revealed by drill-cores favours a Cambrian junction between Central and South Dobrogea.


2021 ◽  
pp. jgs2021-070
Author(s):  
Isabel C. Zutterkirch ◽  
Christopher L. Kirkland ◽  
Milo Barham ◽  
Chris Elders

Detrital zircon U-Pb geochronology has enabled advances in the understanding of sediment provenance, transportation pathways, and the depositional age of sedimentary packages. However, sample selection and processing can result in biasing of detrital zircon age spectra. This paper presents a novel approach using in-situ detrital zircon U-Pb measurements on thin-sections to provide greater confidence in maximum depositional ages and provenance interpretations. New U-Pb age data of 310 detrital zircon grains from 16 thin-sections of the Triassic Mungaroo Formation from two wells in the Northern Carnarvon Basin, Australia, are presented. Whilst detrital zircon age modes are consistent with previous work, there are some differences in the relative proportions of age modes, which is partly attributed to a lack of small grains in hand-picked grain mounts. The relative sample bias is quantified via grain size comparison of dated zircon (in thin-sections or hand-picked mounts) relative to all zircons identified in bulk-mounts and thin-sections. The youngest age mode (∼320 – 195 Ma) is consistent with an active margin to the north, likely South West Borneo and/or Lhasa terrane. The dated zircons reveal a maximum depositional age of 197 Ma for the upper part of Mungaroo Formation, suggesting deposition continued into the Early Jurassic.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5628911


2021 ◽  
Author(s):  
Mahyra Tedeschi ◽  
Humberto Reis ◽  
Laura Stutenbecker ◽  
Matheus Kuchenbecker ◽  
Bruno Ribeiro ◽  
...  

<p>Detrital zircon records are prone to several sources of bias that can compromise sediment provenance investigations based on U-Pb ages. High-temperature metamorphism (>850 ºC) is herewith addressed as a natural cause of bias since U-Pb zircon data from rocks submitted to these extreme, often prolonged conditions, frequently display protracted apparent concordant geochronological U-Pb records. The resulting spectrum can originate from disturbance of the primary U-Pb zircon system, likewise from subsequent recrystallization and crystallization processes during multiple and/or prolonged metamorphic events. Consequently, a high-grade metamorphosed igneous rock can exhibit a zircon age spectrum similar to that produced by polymict sedimentary rocks, thereby inducing provenance misinterpretations if this rock becomes a source for a sediment. A polymict sedimentary source that undergoes such high temperatures could potentially generate an even more intricate spectrum. Archean, Neoproterozoic and Paleozoic metamorphic rocks from the literature, dated by different techniques (SIMS and LA-ICP-MS), are employed as examples to demonstrate the resulting complications.  The compilation shows that (1) high-temperature metamorphism may generate age peaks of unclear or lacking geological meaning, and (2) the interpretation of detrital zircon age spectra depends on the timing of the metamorphic event (pre- or post-depositional). When high-temperature metamorphic rocks are eroded in uplifted areas, the youngest population of a detrital spectrum represents the maximum depositional age through metamorphic zircon from the source. If a sedimentary succession was subjected to high-temperature metamorphic conditions after deposition, its youngest zircon population more likely records the metamorphism, and the maximum depositional age, as well as older sources cannot be directly accessed. To evaluate the presence of high-temperature metamorphism-related bias in a given detrital zircon sample, we suggest a workflow for data acquisition and interpretation, combining a multi-proxy approach with: in situ U-Pb dating coupled with Hf analyses to retrieve the isotopic composition of the sources, and the integration of a petrochronological investigation to typify fingerprints of the (ultra)high-temperature metamorphic event.</p>


2019 ◽  
Vol 56 (3) ◽  
pp. 247-266
Author(s):  
Ian Anderson ◽  
David H. Malone ◽  
John Craddock

The lower Eocene Wasatch Formation is more than 1500 m thick in the Powder River Basin of Wyoming. The Wasatch is a Laramide synorgenic deposit that consists of paludal and lacustrine mudstone, fluvial sandstone, and coal. U-Pb geochronologic data on detrital zircons were gathered for a sandstone unit in the middle part of the succession. The Wasatch was collected along Interstate 90 just west of the Powder River, which is about 50 km east of the Bighorn Mountain front. The sandstone is lenticular in geometry and consists of arkosic arenite and wacke. The detrital zircon age spectrum ranged (n=99) from 1433-2957 Ma in age, and consisted of more than 95% Archean age grains, with an age peak of about 2900 Ma. Three populations of Archean ages are evident: 2886.6±10 Ma (24%), 2906.6±8.4 Ma (56%) and 2934.1±6.6 Ma (20%; all results 2 sigma). These ages are consistent with the age of Archean rocks exposed in the northern part of the range. The sparse Proterozoic grains were likely derived from the recycling of Cambrian and Carboniferous strata. These sands were transported to the Powder River Basin through the alluvial fans adjacent to the Piney Creek thrust. Drainage continued to the north through the basin and eventually into the Ancestral Missouri River and Gulf of Mexico. The provenance of the Wasatch is distinct from coeval Tatman and Willwood strata in the Bighorn and Absaroka basins, which were derived from distal source (>500 km) areas in the Sevier Highlands of Idaho and the Laramide Beartooth and Tobacco Root uplifts. Why the Bighorn Mountains shed abundant Eocene strata only to the east and not to the west remains enigmatic, and merits further study.


2016 ◽  
Vol 448 (1) ◽  
pp. 145-159 ◽  
Author(s):  
Tianchen He ◽  
Ying Zhou ◽  
Pieter Vermeesch ◽  
Martin Rittner ◽  
Lanyun Miao ◽  
...  

2020 ◽  
Vol 157 (11) ◽  
pp. 1877-1897 ◽  
Author(s):  
J.-X. Wang ◽  
K.-X. Zhang ◽  
Brian F. Windley ◽  
B.-W. Song ◽  
X.-H. Kou ◽  
...  

AbstractAccretionary orogens contain key evidence for the conversion of oceanic to continental crust. The late tectonic history and closure time of the Palaeo-Asian Ocean are recorded in the Mazongshan subduction–accretion complex in the southern Beishan margin of the Central Asian Orogenic Belt. We present new data on the structure, petrology, geochemistry and zircon U–Pb isotope ages of the Mazongshan subduction–accretion complex, which is a tectonic mélange with a block-in-matrix structure. The blocks are of serpentinized peridotite, basalt, gabbro, basaltic andesite, chert and seamount sediments within a matrix that is mainly composed of fore-arc-trench turbidites. U–Pb zircon ages of two gabbros are 454.6 ± 2.5 Ma and 434.1 ± 3.6 Ma, an andesite has a U–Pb zircon age of 451.3 ± 3.5 Ma and a tuffaceous slate has the youngest U–Pb zircon age of 353.6 ± 5.1 Ma. These new isotopic ages, combined with published data on ophiolitic mélanges from central Beishan, indicate that the subduction–accretion of Beishan in the southernmost Central Asian Orogenic Belt lasted until Late Ordovician – Early Carboniferous time. Structure and age data demonstrate that the younging direction of accretion was southwards and that the subduction zone dipped continuously to the north. Accordingly, these results record the conversion of oceanic to continental crust in the southern Beishan accretionary collage.


2020 ◽  
pp. 1-17
Author(s):  
Bo Hui ◽  
Yunpeng Dong ◽  
Feifei Zhang ◽  
Shengsi Sun ◽  
Shuai He

Abstract The Yangtze Block in South China constitutes an important Precambrian landmass in the present East Asian continent. The Neoproterozoic sedimentary successions of the Hengdan Group in the NW Yangtze Block record essential information for deciphering the Neoproterozoic tectonics along the NW margin. However, its depositional age, provenance and tectonic properties remain uncertain. Here, a combined analysis of detrital zircon U–Pb dating and geochemistry is performed on representative samples from the Hengdan Group. Concordant dating results of samples from the bottom and upper parts constrain the maximum depositional age at c. 720 Ma. Detrital zircon age patterns of samples reveal a uniformly pronounced age peak at c. 915–720 Ma, which is consistent with the magmatic pulses in domains at the NW end of the Yangtze Block. In addition, these samples display left-sloping post-Archaean Australian shale (PAAS)-normalized rare-earth element patterns and variable trace element patterns, resembling sediments accumulated in a basin related to an active continental margin geodynamic setting. Provenance analysis reveals that the main sources featured intermediate to felsic components, which experienced rapid erosion and sedimentation. These integrated new investigations, along with previous compilations, indicate that the Hengdan Group might have been deposited in a fore-arc basin controlled by subduction beneath the Bikou Terrane. Thus, such interpretation further supports proposals for subduction-related tectonics along the western margin of the Yangtze Block during the early Neoproterozoic.


Geology ◽  
2005 ◽  
Vol 33 (8) ◽  
pp. 637-640 ◽  
Author(s):  
G. Gutiérrez-Alonso ◽  
J. Fernández-Suárez ◽  
Alan S. Collins ◽  
I. Abad ◽  
F. Nieto

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.


2006 ◽  
Vol 43 (5) ◽  
pp. 571-591 ◽  
Author(s):  
Daniela A Vallini ◽  
William F Cannon ◽  
Klaus J Schulz

A geochronological study of the Chocolay Group at the base of the Paleoproterozoic Marquette Range Supergroup in Michigan, Lake Superior Region, is attempted for the first time. Age data from detrital zircon grains and hydrothermal xenotime from the basal glaciogenic formation, the Enchantment Lake Formation, and the stratigraphically higher Sturgeon Quartzite and its equivalent, the Sunday Quartzite, provide maximum and minimum age constraints for the Chocolay Group. The youngest detrital zircon population in the Enchantment Lake Formation is 2317 ± 6 Ma; in the Sturgeon Quartzite, it is 2306 ± 9 Ma, and in the Sunday Quartzite, it is 2647 ± 5 Ma. The oldest hydrothermal xenotime age in the Enchantment Lake Formation is 2133 ± 11 Ma; in the Sturgeon Quartzite, it is 2115 ± 5 Ma, and in the Sunday Quartzite, it is 2207 ± 5 Ma. The radiometric age data in this study implies the depositional age of the Chocolay Group is constrained to ~2.3–2.2 Ga, which proves its correlation with part of the Huronian Supergroup in the Lake Huron Region, Ontario, and reveals the unconformity that separates the Chocolay Group from the overlying Menominee Group is up to 325 million years in duration. The source(s) of the ~ 2.3 Ga detrital zircon populations in the Enchantment Lake Formation and Sturgeon Quartzite remains an enigma because no known rock units of this age are known in the Michigan area. It is speculated that once widespread volcano-sedimentary cover sequences in Michigan were removed or concealed prior to Chocolay Group deposition. The hydrothermal xenotime ages probably reflect basinal hydrothermal fluid flow associated with the period of extension, involving rifting and major dyke formation, that affected the North American provinces between 2.2 and 2.1 Ga.


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