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Detrital zircon U‐Pb data are routinely used to assess provenance in sedimentary systems. However, recent studies have suggested that zircon provenance interpretation may be biased by grain‐size‐dependent selective transport and deposition. In this study, we present zircon grain‐size and U‐Pb data from 11 sandstone and 11 mudstone samples from the late Paleozoic Eagle and Paradox basins to test whether apparent provenance changes between sandstone and mudstone samples can be explained by changes in zircon grain‐size alone. The Eagle and Paradox basins formed in association with the Ancestral Rocky Mountains (ARM). These basins provide an excellent system to test grain‐size/provenance relationships because they are filled with cyclic stratigraphy that records, via grain size and facies changes, flooding/exposure driven by interglacial/glacial cycles. These cycles are interpreted to have substantially altered sediment transport pathways and provenance of ARM‐related sedimentary rocks. Data presented here suggest that although zircon grain size does correlate to sample grain size in most samples, age spectra appear to be independent of grain size. As such, differences in age spectra between sandstone and mudstone samples appear to be the result of changes in relative inputs of two endmember sources: (1) grains eroded from adjacent basement‐cored ARM uplifts and (2) far‐traveled sediment sourced from outside the ARM system. The data presented in this study also provide a successful proof‐of‐concept test for a manual method of determining zircon grain size. This method is simple and straightforward and can be applied to any sample analyzed using the Chromium off‐line targeting software. Key Points: Detrital zircon age spectra, grain size, and sample grain size are correlated, but this does not affect provenance interpretationsWe present a simple method for quantifying grain size in detrital zircon samples [ABSTRACT FROM AUTHOR]

The late Carboniferous to Triassic tectonic history of eastern Australia includes important periods of regional-scale crustal extension and contraction. Evidence for these periods of tectonism is recorded by the extensive Pennsylvanian (late Carboniferous) to Triassic basin system of eastern Australia. In this study, we investigate the use of U-Pb dating of detrital zircons in reconstructing the tectonic development of one of these basins, the eastern Galilee Basin of Queensland. U-Pb detrital zircon ages were obtained from samples of stratigraphically well-constrained Cisuralian and Lopingian (early and late Permian, respectively) sandstone in the Galilee Basin. Detrital zircons in these sandstones are dominated by a population with ages in the range of 300-250 Ma, and ages from the youngest detrital zircons closely approximate depositional ages. We attribute these two fundamental findings to (1) appreciable derivation of detrital zircons in the Galilee Basin from the New England Orogen of easternmost Australia and (2) syndepositional magmatism. Furthermore, Cisuralian sandstone of the Galilee Basin contains significantly more >300 Ma detrital zircons than Lopingian sandstone. The transition in detrital zircon population, which is bracketed between 296 and 252 Ma based on previous high-precision U-Pb zircon ages from Permian ash beds in the Galilee Basin, corresponds with the Hunter-Bowen Orogeny and reflects a change in the Galilee Basin from an earlier extensional setting to a later foreland basin environment. During the Lopingian foreland basin phase, the individual depocentres of the Galilee and Bowen basins were linked to form a single and enormous foreland basin that covered >300 000 km2 in central and eastern Queensland. [ABSTRACT FROM AUTHOR]

This paper reports LA–ICP–MS U–Pb zircon ages and geochemical data from the Zhaobeishan Formation on the northern margin of the North China Craton (NCC). These data are used to better constrain the depositional age, provenance characteristics and tectonic evolution regarding particularly the final closure of the Paleo-Asian Ocean in the eastern segment of the Central Asian Orogenic Belt (CAOB). Major, trace, and rare earth element (REE) characteristics show that the Zhaobeishan Formation formed in an active continental margin environment. Clastic particles in the formation display varied provenance sources from basic to intermediate–acid arc igneous rocks. Twenty-two zircon rim analyses from a diopside granulite yield a weighted mean 206 Pb/ 238 U age of 245 ± 2 Ma (MSWD = 3.2), which represents the timing of metamorphism, whilst 45 concordant zircon core analyses yield apparent ages of 257–2592 Ma that fall into eight age populations. The depositional age of the Zhaobeishan Formation is constrained to be between 257 and 245 Ma, based on the youngest concordant 206 Pb/ 238 U age of the zircon cores and the metamorphic age of zircon rims. The provenance of the formation is dominated by Paleozoic magmatic arcs of the northern margin of the NCC, with material also derived from the interior of the NCC and the Songliao Block (SLB). Mixed detrital zircons from the NCC and SLB, which were separated by the Paleo-Asian Ocean, indicate a short distance between the NCC and SLB, and a narrow ocean at the time of sedimentation. The Paleo-Asian Ocean still existed in the eastern segment of the CAOB during the late Permian to Early Triassic, and the metamorphic age (ca. 245 Ma) of zircon rims in the diopside granulite sample may represent the timing of final closure of the Paleo-Asian Ocean. [ABSTRACT FROM AUTHOR]

The Archean stage of sedimentation has been first substantiated for the granulite-gneiss terranes of the Sharyzhalgai uplift (southwest of the Siberian craton). High-alumina paragneisses contain detrital zircons varying in age from 3.7 to 2.74 Ga and corresponding in REE patterns to magmatic zircons. The Paleoproterozoic (~ 1.86 Ga) metamorphic zircons are strongly depleted in HREE and Y as a result of their formation in equilibrium with garnet. Zircons with an age of ~ 2.5 Ga also show geochemical signs of alteration during metamorphism. The formation of terrigenous sedimentary rocks preceded the Neoarchean stage of magmatism (~ 2.7-2.6 Ga), and their metamorphism occurred at the Neoarchean-Paleoproterozoic boundary and in the Late Paleoproterozoic. The sources of detrital zircons were mainly Mesoarchean rocks, such as magmatic protoliths of granulites and intermediate-felsic magmatic rocks. The single Eoarchean and Paleoarchean detrital zircon grains in the paragneisses are the first direct evidence for the oldest crust (up to 3.7 Ga) in the granulite terranes of the Sharyzhalgai uplift. The set of geochronological data for granulites and paragneisses suggests the following sequence of geologic events for the granulite-gneiss terranes: ~ 3.7—the beginning of crustal formation, 3.4-3.2 Ga—intermediate-felsic magmatism, including the recycling of the more ancient crust, and ~ 3.0 Ga—coeval magmatic and metamorphic processes and differentiation of the continental crust. Thus, the whole cycle from the beginning of crustal growth to the crustal differentiation and turn into continental crust proceeded from 3.7 to 3.0 Ga. [ABSTRACT FROM AUTHOR]

Combined with the previous detrital zircons U-Pb ages of the two Precambrian successions, i.e. the Shilu Group and the Shihuiding Formation in Hainan Island of South China, the in situ Lu-Hf isotopes of detrital zircons were performed to evaluate the growth and reworking of Hainan Island continental crust during Precambrian. The results of 171 Hf-isotopic analyses on zircon grains from the Shihuiding Formation yield 176 Hf/ 177 Hf ratios between 0.280786 and 0.281188, 176 Lu/ 177 Hf ratios between 0.000228 and 0.003388, Hf model ages (T DM C ) between 3.8 Ga and 1.2 Ga, and ε Hf (t) values ranging from −12.5 to +10.6. The analyzed results of 272 Hf-isotopic data on zircon grains from the Shilu Group exhibit a wide range of 176 Hf/ 177 Hf ratios (0.280810–0.282512), 176 Lu/ 177 Hf ratios (0.000062–0.004060), T DM C ages (3.7 Ga–1.1 Ga), and ε Hf (t) values (−20.5 to +12.3). The continental crust of Hainan Island maybe appeared firstly at ca. 4.0–3.8 Ga and then was reworked. The 91.8% of detrital zircon grains from the Shihuiding Formation and 93.8% of the ones from the Shilu Group have crustal incubation time larger than 300 Ma, indicating an involvement of reworked materials into the sedimentation of both the successions. Unambiguously, the crustal basement rocks in Hainan Island were formed mainly through reworking the previous continental components with minor input of juvenile materials. The generation of juvenile curst in Hainan Island predominantly occurred at ca. 2.7 Ga and ca. 1.5–1.0 Ga, which are consistent with that for the assembly of the Kenorland, and the Columbia breakup and subsequent amalgamation of the Rodinia, respectively. The present study further reveals that the crustal growths in Hainan Island are present at 2.7 Ga, 2.3 Ga and 2.1–1.8 Ga, which is more favorable to the episodic growth mode. Moreover, a rough trend of decreasing maximum crustal incubation time of Hainan Island demonstrates that the incubation time of the juvenile crust is shorter when compared with that of the Cathaysia Block in the late Mesoproterozoic. Link to the previously reported geological works, we consider that Hainan Island did not share the same evolution history with the Cathaysia Block of South China during Precambrian. [ABSTRACT FROM AUTHOR]

The ∼800 km long Heihe River in northwestern China originates from the North Qilian Mountain, and passes through the Beishan Mountain before it reaches the Juyanhai Lake. Geologically, the river crosscuts the North Qilian Orogenic Belt, the Alax Terrane, and the Beishan Orogenic Belt. LA-ICP-MS U-Pb dating of detrital zircon from Heihe River sediments shows four age groups: 2700–1700 Ma, 1700–650 Ma, 650–358 Ma, and 358–230 Ma, and age peaks at ∼2450 Ma, ∼1850 Ma, ∼950 Ma, ∼520 Ma, 505 Ma, ∼480 Ma, ∼450 Ma, ∼430 Ma, ∼380 Ma, ∼320 Ma, and ∼295 Ma. The age distribution patterns indicate that Heihe River sediments were mainly sourced from the North Qilian Orogenic Belt. The detrital zircon ages demonstrate that the North Qilian Orogenic Belt may have Archean to late Paleoproterozoic rocks. Several tectonothermal events are also identified: opening of the North Qilian Ocean (part of the Paleo-Tethys Ocean) at early Neoproterozoic, subduction of oceanic lithosphere and formation of a trench-arc-basin system at late Neoproterozoic to late Ordovician, closure of the oceanic basin at late Ordovician, and collision of the Qaidam and Alax terranes at early Devonian. Our study indicates that the formation of the North Qilian Orogenic Belt was mainly related to the formation and closure of the Paleo-Tethys Ocean. [ABSTRACT FROM AUTHOR]

We have conducted the first geochronological study of the ultramafic–mafic succession (the Waterberg Project) located in the Southern Marginal Zone of the Limpopo Belt north of the Northern Lobe of the Bushveld Complex using U/Pb dating on zircons extracted from both mineralized reefs as well as on detrital zircons of the Waterberg Group unconformably overlying the mafics. This contribution is the first in a series of publications describing the well-mineralized succession and will therefore give an overview of the local geology. U/Pb baddeleyite ages for the main mafic sill intruding the area supplement the data. The succession is extremely well mineralized and therefore of interest to the wider geological community. The intrusion ages for the Lobe are 2059 ± 3 and 2053 ± 5 Ma and within error coeval with the intrusion ages of the Bushveld Complex. Detrital zircon age probability density distributions indicate a maximum age of deposition of c. 2045 Ma for the Waterberg Group and show abundant peaks of Archean age. Paleoproterozoic zircons are interpreted to represent zircon from the detritus of the now eroded roof rocks of the lobe, while the Archean zircons are most likely sourced from the Limpopo Complex to the northeast. The major dolerite sill intruding the project area has been confirmed to belong the Umkondo Igneous Province with a baddeleyite age of 1125 ± 5 Ma. The combination of these new age dates, local geology and existing literature is used to argue that (i) the ultramafic–mafic succession is related to the Bushveld Complex; (ii) a significant unconformity is present between igneous rocks and the overlying sediments, and (iii) the area was exposed to a level of Paleoproterozoic tectonism not previously observed in the Bushveld Complex. [ABSTRACT FROM AUTHOR]

In this article, we presentin situU–Pb and Lu–Hf isotope data for Upper Triassic detritus in the Sichuan region of northwestern South China, which was a foreland basin during the Late Triassic. The aim is to determine the provenance of sediments in the foreland basin and to constrain the evolution of the surrounding mountain belts. U–Pb age data for the Late Triassic detrital zircons generally show populations at 2.4–2.6 Ga, 1.7–1.9 Ga, 710–860 Ma, 410–460 Ma, and 210–300 Ma. By fitting the zircon data into the tectonic, sedimentologic, and palaeographic framework, we propose that the north Yangtze Block and South Qinling–Dabie Orogen were the important source areas of sediments in the northern part of the foreland basin, whereas the Longmen Shan thrust-fold belt was the main source region for detritus in other parts of the foreland basin. The South Qinling–Dabie Orogen could also have served as a physical barrier to block most detritus shed from the southern North China Block into the foreland basin during the sedimentation of the Xujiahe Formation. Our results also reveal that part of the flysch from the eastern margin of the Songpan–Ganzi region had been displaced into the Longmen Shan thrust-fold belt before the deposition of the foreland basin sediments. In addition, the Lu-Hf data indicate that Phanerozoic igneous rocks in central China show insignificant formation of the juvenile crust. [ABSTRACT FROM PUBLISHER]

The Paleoproterozoic Wopmay orogen is modeled as a simple arc-continent collision involving the Archean Slave craton and an enigmatic continental arc terrane termed the Hottah terrane. Hottah is a composite terrane that includes a juvenile 2.6-2.1 Ga basement and a younger 1.93-1.90 Ga continental arc. The extent and crustal age structure of the terrane is poorly known which limits interpretations as to its origin, and eventual role in the development of the orogen. Multi-isotopic (U-Pb, Hf, O) analyses of detrital zircon from rocks of the Hottah terrane and its cover sequence are used to indirectly evaluate its age and crustal characteristics. The data confirm that ca 2.6-2.1 Ga crust is an important component of the terrane but Hf isotopic data indicate mostly non-juvenile compositions consistent with recycled Neoarchean crust sources. Ages of detrital zircon are distinct from those expected of the Slave craton but are similar to adjacent 2.0-1.90 Ga Paleoproterozoic terranes of northwestern Laurentia. The similarity to terranes such as the Ksituan/Buffalo Head and Taltson-Thelon magmatic zones, south and east of the Wopmay Orogen indicate that Hottah could represent a terrane that initially evolved adjacent to the earliest assembled parts of the Nuna continent between 2.0 and 1.9 Ga, and was rifted prior to the collision with the Slave margin that produced the Calderian orogeny. [ABSTRACT FROM AUTHOR]

New SHRIMP U-Pb ages of detrital zircons from Neoproterozoic low-grade metasandstones of the Schist-Graywacke Complex (Central Iberian Zone, Iberian Massif) sampled just below and above the intra-Alcudian unconformity at two selected locations contribute to reconstruct the geodynamic evolution of Iberia during the Cadomian orogeny in the north Gondwana margin. The youngest zircons (i.e., maximum depositional age) in the Lower Alcudian are c. 580-576 Ma, while those in the Upper Alcudian are c. 555-552 Ma. The obtained remarkable time gap of about 21 Ma supports the existence of a tectonic event in between. This event resulted in moderate folding (without related foliation/metamorphism) that verticalized the Lower Alcudian previous to the deposition of the Upper Alcudian. Additional evidence of late Cadomian tectonothermal events elsewhere in Iberia also fit in the interval c. 560-550 Ma. Combined with other geological data, the most probable maximum depositional ages are c. 580-560 Ma for the Lower Alcudian (previous to the late Cadomian folding event) and c. 550-540 Ma for the Upper Alcudian (previous to the deposition of the overlying Pusian Group and Lower Cambrian sandstones and limestones). A comparison of the new zircon age spectra with possible source areas verifies recent studies that point to the Cadomian foreland in the north Gondwana continent affected by the Pan-African orogeny: the West African Craton and/or the Saharan Metacraton. Furthermore, ongoing Cadomian arc-related magmatism in Iberia (c. 605-545 Ma) could have contributed as a local zircon source. The end of the Cadomian activity is marked by a transient stage (ephemeral Lower Cambrian platform) which preceded widespread Cambro-Ordovician rifting of north Gondwana. [ABSTRACT FROM AUTHOR]

New U–Pb age data and Hf isotope systematics on zircons from Middle Devonian and Lower Carboniferous units from NE China provide evidence for the depositional age of these poorly constrained units as well as for the timing of the collision between the Erguna (Ergun in some references) and Xing’an blocks in the eastern end of Central Asian Orogenic Belt (CAOB). The detrital zircons from the Devonian and Carboniferous sandstones yielded similar age spectra in probability diagrams showing three distinct peaks at ∼450 Ma, ∼500 Ma and ∼540 Ma, respectively, along with Proterozoic and Archean age groups, except for a relatively young age population at ∼360 Ma detected for zircons from the Hongshuiquan Fm. The dating results suggest that the depositional time of the Niqiuhe Fm. should be younger than Late Silurian, as indicated by the youngest 422-Ma detrital zircon from this Fm., and that of the Hongshuiguan Fm. with a youngest detrital age of ca. 338 Ma, is younger than Middle Mississippian (Visean), which is in accordance with those inferred from biostratigraphic data. These dominant age groups are widely found in the Erguna and Xing’an blocks, it is suggested that the sediments of the studied sandstones from Niuqiuhe and Hongshuiquan Fms come mainly from the Erguna and Xing’an blocks. The ε Hf ( t ) value of dated zircons from our sandstones has a wide range (−21 to 16), which shows a mixed signature of that from Paleozoic granitoids in Xing’an block (6–17) and Erguna block (−2 to 6), indicating that Erguna and Xing’an blocks had connected before the Middle Devonian deposition of the Niqiuhe Fm. (422 ± 5 Ma). Combined with the age data, we suggest that the Erguna and Xing’an blocks started to accrete at ∼540 Ma, reached the peak of collision at ∼500 Ma, and went into the post-collision stage from ∼490 to ∼450 Ma. The study provides more evidences and constraints for the early Paleozoic evolutions of the inter-continental block amalgamations and accretions in CAOB. [ABSTRACT FROM AUTHOR]