scholarly journals New detrital zircon U-Pb ages and Lu-Hf isotopic data from metasedimentary rocks along the western boundary of the composite Avalon terrane in the southeastern New England Appalachians

2022 ◽  
Author(s):  
Allison R. Severson ◽  
Yvette D. Kuiper ◽  
G. Nelson Eby ◽  
Hao-Yang Lee ◽  
J. Christopher Hepburn

ABSTRACT West Avalonia is a composite terrane that rifted from the supercontinent Gondwana in the Ordovician and accreted to Laurentia during the latest Silurian to Devonian Acadian orogeny. The nature and extent of West Avalonia are well constrained in Nova Scotia, New Brunswick, and Newfoundland, Canada, by U-Pb detrital zircon data and/ or isotope geochemistry of (meta)sedimentary and igneous rocks. The southeastern New England Avalon terrane in eastern Massachusetts, Connecticut, and Rhode Island has generally been interpreted as an along-strike continuance of West Avalonia in Canada, but the ages and origins of metasedimentary units along the western boundary of the Avalon terrane in Massachusetts and Connecticut remain poorly constrained. In this study, new detrital zircon U-Pb and Lu-Hf laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) data from three samples of metasedimentary units along the western boundary of the southeastern New England Avalon terrane in Connecticut and Massachusetts were compared with existing data to test whether these metasedimentary units can be correlated along strike. The data were also compared with existing detrital zircon U-Pb and εHf data in New England and Canada in order to constrain the extent and provenance of West Avalonia. The maximum depositional age of two of the three detrital zircon samples analyzed in this study, based on the youngest single grain in each sample (600 ± 28 Ma, n = 1; 617 ± 28 Ma, n = 1) and consistency with existing analyses elsewhere in the southeastern New England Avalon terrane, is Ediacaran, while that of the third sample is Tonian (959 ± 40 Ma, n = 4). Detrital zircon analyses of all three samples from this study showed similar substantial Mesoproterozoic and lesser Paleoproterozoic and Archean populations. Other existing detrital zircon U-Pb data from quartzites in the southeastern New England Avalon terrane show similar Tonian populations with or without Ediacaran grains or populations. Most published detrital zircon U-Pb data from (meta)sedimentary rocks in West Avalonia in Canada yielded Ediacaran youngest detrital zircon age populations, except for a quartzite unit within the Gamble Brook Formation in the Cobequid Highlands of Nova Scotia, which showed a Tonian maximum depositional age, and otherwise a nearly identical detrital zircon signature with rocks from the southeastern New England Avalon terrane. All samples compiled from the southeastern New England Avalon terrane and West Avalonia in Canada show main age populations between ca. 2.0 Ga and ca. 1.0 Ga, with major peaks at ca. 1.95, ca. 1.50, ca. 1.20, and ca. 1.00 Ga, and minor ca. 3.1–3.0 Ga and ca. 2.8–2.6 Ga populations. The εHf(t) values from the three samples yielded similar results to those from West Avalonia in Canada, suggesting that both regions were derived from the same cratonic sources. The εHf(t) values of all West Avalonian samples overlap with both Amazonia and Baltica, suggesting that there is a mixed signature between cratonic sources, possibly as a result of previous collision and transfer of basement fragments between these cratons during the formation of supercontinent Rodinia, or during subsequent arc collisions.

2021 ◽  
Author(s):  
Daniel Brennan ◽  
et al.

Individual sample detrital zircon results, alternative maximum depositional age calculations, conventional laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) methodology, rapid LA-ICP-MS methodology, sample locations, and detrital zircon U-Pb/Lu-Hf results for all analyses and compiled U-Pb data.<br>


2016 ◽  
Vol 53 (3) ◽  
pp. 219-230 ◽  
Author(s):  
Xiao Ma ◽  
Kunguang Yang ◽  
Xuegang Li ◽  
Chuangu Dai ◽  
Hui Zhang ◽  
...  

The Jiangnan Orogeny generated regional angular unconformities between the Xiajiang Group and the underlying Sibao Group in the western Jiangnan Orogen along the southeastern margin of the Yangtze Block in southeast Guizhou, South China. Laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) U–Pb zircon dating of two samples of the Motianling granitic pluton yielded U–Pb zircon ages of 826.2 ± 3.4 and 825.5 ± 6.1 Ma, with an average age of 825.6 ± 3.0 Ma, which is considered the minimum depositional age of the Sibao Group. The U–Pb ages of the youngest detrital zircon grains from the Sibao Group and the Xiajiang Group yielded average ages of 834.9 ± 3.8 and 794.6 ± 4.2 Ma, respectively. The depositional age of the Sibao Group can be constrained at 825–835 Ma, and deposition of the Xiajiang Group did not begin before ca. 800 Ma. These results suggest that the Jiangnan Orogeny, which led to the assembly of the Yangtze and Cathaysia blocks, ended at 795–835 Ma on the western segment of the Jiangnan Orogen. The detrital zircon distribution spectrums of the Sibao and Xiajiang groups suggest a provenance from Neoproterozoic basement sedimentary sequences along with a mixture of local Neoproterozoic subduction-related felsic granitoids, distant plutons from the western Yangtze Block and eastern Jiangnan Orogen, and recycled materials from the interior of the Yangtze Block. By comparing the basin evolution histories and magmatic and metamorphic events along the continental margins of the Rodinia supercontinent, it is proposed that the South China Block might have been located at the periphery, adjacent to North India and East Antarctica, rather than in the interior of Rodinia in Neoproterozoic time.


2021 ◽  
Author(s):  
Daniel Brennan ◽  
et al.

Individual sample detrital zircon results, alternative maximum depositional age calculations, conventional laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) methodology, rapid LA-ICP-MS methodology, sample locations, and detrital zircon U-Pb/Lu-Hf results for all analyses and compiled U-Pb data.<br>


Author(s):  
David M. Chew ◽  
Nicola Fallon ◽  
Christine Kennelly ◽  
Quentin Crowley ◽  
Michael Pointon

ABSTRACTThe Dalradian Supergroup contains three distinct glacigenic units, formerly termed ‘Boulder Beds’, which are correlated with widespread Neoproterozoic glaciations. The oldest and thickest unit, the Port Askaig Formation, marks the Appin–Argyll group boundary of the Dalradian Supergroup and has been correlated with the Middle Cryogenian (Sturtian) glaciation. The Auchnahyle Formation, a diamictite-bearing sequence near Tomintoul in NE Scotland, exhibits strong lithological similarities to the Port Askaig Formation. Both these glacigenic ‘Boulder Bed’ units contain abundant dolomite clasts in their lower parts and more granitic material at higher levels. Both metadiamictite units are overlain by thick shallow-marine quartzite units. C isotope data from Appin Group carbonate strata below the Auchnahyle Formation support this correlation. U–Pb laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) detrital zircon data from the Auchnahyle Formation metadiamictite differ slightly from the Port Askaig Formation, but are similar to detrital zircon spectra obtained from the Macduff Formation, a diamictite unit in the younger Southern Highland Group of the Dalradian Supergroup; both apparently reflect derivation from local basement rocks. No detritus younger than 0·9 Ga is observed, so the data do not constrain significantly the depositional age of the glacial strata. A thin tholeiitic pillow basalt unit in the lower part of the Auchnahyle Formation is geochemically distinct from pre-tectonic metadolerite sills and from basic metavolcanic rocks up-section. A Sturtian (c. 720–700 Ma) age for the Auchnahyle Formation metadiamictite would imply that this basaltic volcanism represents the oldest recorded volcanic activity in the Dalradian Supergroup and is inferred to represent an early, local phase of proto-Iapetan rifting within the Rodinian supercontinent.


2021 ◽  
Author(s):  
Allison Severson ◽  
et al.

U-Pb LA-ICP-MS detrital zircon data for three samples collected along the western boundary of the Avalon terrane in southeastern New England


2021 ◽  
Author(s):  
Daniel Brennan ◽  
et al.

Individual sample detrital zircon results, alternative maximum depositional age calculations, conventional laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) methodology, rapid LA-ICP-MS methodology, sample locations, and detrital zircon U-Pb/Lu-Hf results for all analyses and compiled U-Pb data.<br>


2021 ◽  
Author(s):  
Daniel Brennan ◽  
et al.

Individual sample detrital zircon results, alternative maximum depositional age calculations, conventional laser-ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) methodology, rapid LA-ICP-MS methodology, sample locations, and detrital zircon U-Pb/Lu-Hf results for all analyses and compiled U-Pb data.<br>


Solid Earth ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 1291-1312
Author(s):  
Manuel Francisco Pereira ◽  
Cristina Gama ◽  
Ícaro Dias da Silva ◽  
José Brandão Silva ◽  
Mandy Hofmann ◽  
...  

Abstract. Carboniferous siliciclastic and silicic magmatic rocks from the Santa Susana–São Cristovão and Cabrela regions contain valuable information regarding the timing of synorogenic processes in SW Iberia. In this region of the Ossa-Morena Zone (OMZ), late Carboniferous terrigenous strata (i.e., the Santa Susana Formation) unconformably overlie early Carboniferous marine siliciclastic deposits alternating with volcanic rocks (i.e., the Toca da Moura volcano-sedimentary complex). Lying below this intra-Carboniferous unconformity, the Toca da Moura volcano-sedimentary complex is intruded and overlain by the Baleizão porphyry. Original sensitive high-resolution ion microprobe (SHRIMP) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) U–Pb zircon are presented in this paper, providing chronostratigraphic and provenance constraints since available geochronological information is scarce and only biostratigraphic ages are currently available for the Santa Susana–São Cristovão region. Our findings and the currently available detrital zircon ages from Paleozoic terranes of SW Iberia (Pulo do Lobo Zone – PLZ – South Portuguese Zone – SPZ – and OMZ) were jointly analyzed using the K–S test and multidimensional scaling (MDS) diagrams to investigate provenance. The marine deposition is constrained to the age range of ca. 335–331 Ma (Visean) by new U–Pb data for silicic tuffs from the Toca da Moura and Cabrela volcano-sedimentary complexes. The Baleizão porphyry, intrusive in the Toca da Moura volcano-sedimentary complex, yielded a crystallization age of ca. 318 Ma (Bashkirian), providing the minimum age for the overlying intra-Carboniferous unconformity. A comparison of detrital zircon populations from siliciclastic rocks of the Cabrela and Toca de Moura volcano-sedimentary complexes of the OMZ suggests that they are derived from distinct sources more closely associated with the SPZ and PLZ than the OMZ. Above the intra-Carboniferous unconformity, the Santa Susana Formation is the result of the recycling of distinct sources located either on the Laurussian side (SPZ and PLZ) or Gondwanan side (OMZ) of the Rheic suture zone. The best estimate of the crystallization age of a granite cobble which was found in a conglomerate from the Santa Susana Formation yielded ca. 303 Ma (Kasimovian–Gzhelian), representing the maximum depositional age for the terrestrial strata. The intra-Carboniferous unconformity seems to represent a stratigraphic gap of approximately 12–14 Myr, providing evidence of the rapid post-accretion and collision uplift of the Variscan orogenic belt in SW Iberia (i.e., the OMZ, PLZ, and SPZ).


2021 ◽  
Author(s):  
Allison Severson ◽  
et al.

U-Pb LA-ICP-MS detrital zircon data for three samples collected along the western boundary of the Avalon terrane in southeastern New England


2021 ◽  
Author(s):  
Allison Severson ◽  
et al.

U-Pb LA-ICP-MS detrital zircon data for three samples collected along the western boundary of the Avalon terrane in southeastern New England


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