Detrital Zircon Age Spectra Research Articles

Detrital zircon U–Pb isotopes and whole‐rock geochemistry of early Palaeozoic sediments of the Baoshan and Lancang Blocks, SW China: Implications for Proto‐Tethys evolution and Gondwana reconstruction

The palaeogeographic reconstruction of the microcontinents on the northern margin of Gondwanaland and the tectonic evolution model of the Proto‐Tethys in the Early Palaeozoic remain controversial. The Baoshan and Lancang Blocks in SW Yunnan, China, were located on the northern margin of the Gondwana continent during the Early Palaeozoic. In this study, we present new zircon U–Pb ages and whole‐rock geochemistry data for the sedimentary rocks of the Lancang Group in the Lancang Block and the Mengtong Group in the Baoshan Block to reveal the nature of sedimentary provenance with a further tectonic evolution model of the Proto‐Tethys. Our new detrital zircon U–Pb results, in conjunction with the published age of the metamorphic volcanic rock interlayers, suggest that the Mengtong and Lancang groups were probably deposited during the Early Palaeozoic. The Mengtong and Lancang groups have similar detrital zircon age spectra and display three distinctive age peaks at 1.2–1.1 Ga, ~0.95 Ga, and 0.6–0.5 Ga. This implies that the Baoshan‐Lancang Block was situated in the transitional zone between India and Australia on the Gondwana margin and received detritus from both cratons. Combined with abundant volcanic rocks in the Lancang Group and SSZ‐type ophiolites in the Changning‐Menglian belt, the Lancang Block should be reconstructed as a continental island arc of the Baoshan Block in the Early Palaeozoic. The geochemical analysis results show that the sediments of the two strata were primarily sourced from felsic rocks in the upper crust, and they were deposited in the active continental margin. Combined with previous research, we propose a new tectonic evolution model for the Proto‐Tethys Ocean in the Early Palaeozoic, from bisubduction to collisional orogeny.

Geochemistry and zircon geochronology of the Late Triassic volcanic–sedimentary successions in northern Tibet: Implications for the provenance and tectonic evolution of the Mesozoic Qiangtang Basin

The Late Triassic volcanic–sedimentary successions deposited in the Qiangtang Basin are linked with the initiation of the Mesozoic Qiangtang Basin. However, the nature of this basin is hotly debated. Here, we synthesize petrographic, mineralogical, geochemical, and detrital zircon U–Pb age data of these volcanic–sedimentary successions to constrain their chemical weathering history, provenance, and tectonic setting and to reconstruct the tectonic evolution of the Mesozoic Qiangtang Basin. The chemical weathering indices, especially the chemical index of alteration (CIA), are controlled by grain size and hydraulic sorting rather than sediment recycling. Low compositional and textural maturities, high index of compositional variation (ICV) values, and low CIA and plagioclase index of alteration (PIA) values in most samples suggest that the sediments from the Fanghu and north Woruoshan sections are predominantly from low-maturity sources that may have experienced a weak chemical weathering history. Based on provenance-sensitive geochemical indices (La/Th versus Hf, La/Sc versus Co/Th, and Sc/Th versus Cr/Th) and petrographic features, the detrital contributions to the Nadi Kangri Formation siliciclastic rocks are predominantly proximal felsic rocks. Detrital zircon age spectra suggest that the Nadi Kangri Formation siliciclastic rocks exhibit a provenance change from the Fanghu to the well QK-1 area, although all of the rocks were derived from the Qiangtang terrane itself. The Fanghu section was primarily sourced from synchronous magmatic rocks and pre-Triassic strata from the North Qiangtang and Central uplift belt, while well QK-1 was primarily sourced from recycled sediments from the South Qiangtang and Central uplift belt. Therefore, we propose that the Nadi Kangri Formation volcanic–sedimentary successions were deposited in a rift basin and that its evolution was likely related to the interaction of the rapid expansion of the Meso-Tethys Oceanic crust, collapse of the collisional orogen, and rollback of the Jinsha Paleo-Tethys subducting slab during the Late Triassic.

New age constraints on the break-up of Rodinia and amalgamation of southwestern Gondwana from the Choquequirao Formation in southwestern Peru

Abstract The Choquequirao Formation is a >3 km-thick amphibolite-grade succession that outcrops in the Central Andes of southern Peru. To constrain its age and tectonostratigraphic setting, detrital zircon and metamorphic zircon, titanite, and rutile U–Pb isotopic analyses were conducted. Mantle-derived c. 640 Ma detrital zircons constrain the maximum age of the lower part of the succession and 550–490 Ma metamorphic zircon domains constrain its minimum age. The absence of early Paleozoic detrital zircons suggests that deposition predated early Paleozoic orogenesis in southwestern Gondwana. The close similarity of detrital zircon age spectra to those from sediments deposited on the Arequipa basement suggests that the Choquequirao Formation was deposited on the Arequipa Terrane. Metamorphic titanite dates are highly overdispersed, yet they overlap with c. 460 Ma peak metamorphism recorded by metamorphic zircon. Pb-loss pathways displayed by metamorphic titanite have a lower intercept that overlaps with c. 325 Ma metamorphic rutile, which corresponds to Hercynian orogenesis. A poorly constrained upper intercept of c. 510 Ma may correspond to Pampean and/or early Famatinian orogenesis. We interpret the Cryogenian–Ediacaran Choquequirao Formation as having been deposited during the opening of the Palaeo-Iapetus (Puncoviscana–Clymene) Ocean between eastern Arequipa and southern Kalahari prior to the subsequent collision with southwestern Amazonia during the Pampean Orogeny.

Discovery of a >1,000 km Cambrian Eclogite‐Bearing High‐Pressure Metamorphic Belt in the Central Asian Orogenic Belt: Implications for the Final Closure of the Pan‐Rodinian Ocean

AbstractThe immense Central Asian Orogenic Belt (CAOB) records the transition from the Pan‐Rodinian Mirovoi Ocean to the Paleo‐Asian Ocean, but the final closure of the Mirovoi Ocean remains unexplored. Here we document two new eclogite occurrences, located between CAOB microcontinents and the Ediacaran–Cambrian island arc in Mongolia. Pseudosection modeling and geothermobarometry constrain peak conditions of ∼560°C and ∼2.2 GPa for the Urgamal eclogite and ∼715°C and ∼2.0 GPa for the Tsengel eclogite. Zircon U‐Pb dating results suggest the Urgamal eclogite‐facies metamorphism occurred at ∼522 Ma, and the granite gneiss enclosing the eclogite yielded ∼811 Ma crystallization age and ∼519 Ma metamorphic age. Detrital zircon age spectra of the paragneisses associated with the eclogite suggest a probable provenance from the adjacent Zavkhan microcontinent and the Neoproterozoic arc superimposed on the microcontinent. The Tsengel eclogite has a protolith age of ∼853 Ma and an eclogite‐facies metamorphic age of ∼522 Ma, and the associated migmatite gneiss record a ∼520 Ma migmatization event. The rock associations and geochemical affinities indicate that their protoliths represent mafic rocks formed in a continental rift setting and the Early Neoproterozoic subduction–accretion complex, respectively. Their similar tectonic position and metamorphic age suggest that these rocks are part of a single >1,000 km long Cambrian high‐pressure metamorphic belt. The rocks record closure of the Mirovoi Ocean within the CAOB and constrain this crucial event to ∼520 Ma along the western margin of the microcontinents in Mongolia.

Sediment input, alongshore transport, and coastal mixing in the northeastern Gulf of Mexico based on detrital-zircon geochronology

We present detrital-zircon U–Pb geochronology from the Mississippi, Mobile, and Apalachicola rivers, as well as five beach and barrier island deposits to determine sediment sources, alongshore transport, and sediment mixing in the northeastern Gulf of Mexico. The Mississippi River has a distinct age spectrum defined by prominent Cenozoic and Mesozoic populations coupled with minor Appalachian (490-270 Ma), Grenville (1200-900 Ma), Granite-Rhyolite (1500-1300 Ma), and Yavapai-Mazatzal (1800-1600 Ma) populations. The Mobile and Apalachicola rivers exhibit age spectra containing few to no Cenozoic grains, are proportionately dominated by Appalachian and Grenville populations, and have minor populations consisting of Iaptian Rifting/Gondwanan (850-550 Ma), Granite-Rhyolite, and Yavapai-Mazatzal ages. Comparison of U–Pb age spectra and inverse mixing models shows that beach and barrier island deposits are primarily derived of material from the Apalachicola River, with Mobile River contribution being dependent on geographic position west of Mobile Bay. Minor Mississippi River contribution in coastal deposits results from shelf bypass to deep marine sinks and when present is likely associated with recycling of Coastal Plain strata. Metamorphic zircon grain abundance (14–36%) in coastal deposits and chemical-age relationships to southern Appalachian eastern Blue Ridge and Inner Piedmont provinces corroborate Apalachicola and or Mobile river system provenance. Results from this study suggest that anthropogenic influences and hurricanes have little to no effect on the detrital-zircon age spectra at a regional scale, and that the northeastern Gulf of Mexico can be used as an analog for older Cenozoic and Mesozoic source to sink investigations in the eastern Gulf Coastal Plain.

Sediment provenance and stratigraphic correlations of the Paleogene White River Group in the Bighorn Mountains, Wyoming

Detrital zircon ages for tuffaceous sandstones and conglomerates of the White River Group provide insights on Paleogene basin evolution, magmatic activity, and paleodrainage throughout the Laramide broken foreland basin system of the northern Rocky Mountains in the western United States. Nonmarine deposits of the upper Eocene-Oligocene White River Group are preserved irregularly across northern Wyoming and western South Dakota. Residual Laramide uplifts and active magmatic centers supplied clastic and volcaniclastic sediment to broad, low-relief valleys beginning around 40 Ma. Subhorizontal strata of the White River Group are exposed in the elevated Bighorn Mountains (∼2300 to 2800 m), where sections ∼10-50 m thick rest unconformably on Precambrian-Paleozoic rocks along a surface of moderate to low relief (up to 150 m). U-Pb ages were obtained for detrital and igneous (ash-fall) zircons from seven samples (3 tuffaceous sandstones, 2 conglomerates, 2 sandstones) spanning three localities in the Bighorn Mountains (Darton’s Bluff, Hazelton Road, Freeze Out Point). Each locality contains conglomeratic layers, with clasts of local crystalline basement, and interbedded tuffaceous sandstones. Detrital zircon age spectra for four samples reveal peak ages around 2.9 Ga, matching the age of Archean crystalline basement within Bighorn Mountains, and maximum depositional ages (MDAs) of 27 Ma (sample 20BH15; Oligocene) and 35 Ma (sample FO-2; late Eocene). During the Paleogene, the Bighorn Mountains region received sediment from local crystalline basement and long-distance river transport from igneous and sedimentary sources to the west. The Bighorn Mountains were exhumed and stripped of Phanerozoic cover strata by early Eocene time, suggesting that post-Laramide input from Paleozoic-Mesozoic strata was likely from relict highlands of the Cordilleran (Sevier) fold-thrust belt rather than local Laramide block uplifts. In addition, Cenozoic magmatic provinces in the San Juan Mountains and Great Basin are inferred to have contributed volcaniclastic sediment through both eruptive ash clouds and north- to northeast-flowing fluvial systems that reached northeastern Wyoming. The White River Group preserved in the Bighorn Mountains represents localized late Eocene-Oligocene sediment accumulation atop a Laramide basement high coeval with regional deposition across the adjacent Great Plains. Both regions were supplied sediment from alluvial fans and fluvial drainage networks that tapped Laramide basement uplifts, Cordilleran thrust-belt, and foreland sources, along with Cenozoic igneous centers of the western U.S. interior.

Locating northern Qiangtang on the margin of Gondwana or Laurasia? Evidence from detrital zircon geochronology

• The Permian sandstones of the northern Qiangtang terrane are quite possibly sourced from Gondwana-affinity terranes, such as the southern Qiangtang and Lhasa terranes. • The northern and southern Qiangtang terranes were essentially a unified block during the Late Paleozoic. • The northern Qiangtang terrane was located on the northern margin of Gondwana during the Permian. The relationship between the northern Qiangtang terrane and other blocks in Gondwana and Laurasia continents is still controversial. Here we report U-Pb ages of detrital zircons from the Lower-Middle Permian Nuoribagaribao Formation in the northern Qiangtang terrane, which provides new evidence to constrain the tectonic affinity of the northern Qiangtang terrane during the Late Paleozoic. Sandstones from the middle and upper parts of the Nuoribagaribao Formation contain dominant Ordovician to Devonian (480–360 Ma, peaking at 368 Ma) and Late Paleoproterozoic to Early Mesoproterozoic (1800–1400 Ma, peaking at 1557 Ma) detrital zircons. The U-Pb age spectrum of detrital zircons of them is consistent with those of the Carboniferous strata in the southern Qiangtang and Lhasa terranes to the south; this indicates that rather than being sourced from the Yangtze Block to the east and the Eastern Kunlun-Qaidam-Qilian terrane to the north, the sediments of the Nuoribagaribao Formation were most probably sourced from the Carboniferous strata in the southern Qiangtang and Lhasa terranes to the south or shared the same sources as them. The high similarity of detrital zircon age patterns between the northern and southern Qiangtang terranes, together with other lines of geological evidence, such as paleomagnetism and paleontology, indicate that the northern and southern Qiangtang terranes were essentially a unified block during the Late Paleozoic and were located on the northern margin of Gondwana.

The Assabet barcode: Mesoproterozoic detrital zircons in Neoproterozoic strata from Mauritania, West Africa

Detrital zircon data are reported from Mesoproterozoic to Ordovician strata from two tectonic domains in Mauritania: 14 samples from the Taoudeni Basin of the West African Craton and 15 samples from the Mauritanide orogen. Taoudeni Basin samples show four sequential, distinctive detrital zircon age distributions, which we refer to as “barcodes”. From old to young these are the Char, Assabet, Téniagouri, and Oujeft barcodes, each named for a constituent stratigraphic unit. Zircon age maxima are as follows, with the dominant ones in italics. The Char barcode, from Mesoproterozoic (<i>ca.</i> 1100 Ma) strata including the Char Group, yielded zircon age maxima at 2941, 2871, 2703, <i>2447</i>, <i>2076</i>, and <i>2041</i> Ma, all potentially traceable to sources in the West African Craton. The Assabet barcode is from strata, including the eponymous Assabet el Hassiane Group, that were deposited between <i>ca</i>. 883 and <i>ca.</i> 570 Ma; it has age maxima at 2137, 2053, 1769, 1510, <i>1212</i>, 1021, and 936 Ma and a pronounced minimum during Geon 16 (1699–1600 Ma). The Assabet9s Mesoproterozoic to early Neoproterozoic zircons cannot have come from the West African Craton or any of its surrounding orogens. The Téniagouri barcode, which takes its name from the Téniagouri Group, was deposited at <i>ca.</i> 569 Ma; it has dominant maxima at 1983, 1872, <i>1522</i>, <i>1215</i>, 1109, 988, and 601 Ma and resembles the Assabet barcode but with the addition of the youngest population. The Oujeft barcode, named for the Oujeft Group, is from strata deposited between 541 or slightly earlier and 444 Ma or younger, has age maxima at 2124, 2053, 1197, <i>624</i> and <i>579</i> Ma. The Téniagouri and Oujeft barcodes record input from Pan-African orogens. In the Mauritanide orogen, most of the metasedimentary rock units that were sampled yielded detrital zircon age spectra that match one of the Taoudeni Basin barcodes. These results imply new depositional age constraints based on barcode correlation and suggest affinities between Mauritanide strata and the West African Craton. Detrital zircon age distributions that broadly resemble the Assabet barcode occur in the Neoproterozoic of Morocco, Ghana, Greece, Russia, Brazil, and, in the Appalachian orogen of Canada and the United States, Avalonia and Ganderia. The recent Rodinia reconstruction of Evans (2021) restores these far-flung localities to a more compact area, with Avalonia, Ganderia, and other peri-Gondwanan terranes occupying an oblong area between Amazonia, Laurentia, Baltica, and West Africa. Our preferred explanation is that most of these places received detritus via the same continent-scale fluvial system as the West African craton. Among the craton9s nearest Rodinia neighbors in the Evans (2021) reconstruction for 900 Ma, Amazonia has known igneous rocks corresponding to all of the major Assabet age populations, and also a lull, though not a complete magmatic gap, during Geon 16. This is consistent with overall north-directed paleocurrents in the Assabet El Hassiane Group and its correlatives on the West African Craton.

Arctic sediment routing during the Triassic: sinking the Arctic Atlantis

Opening of the Arctic Ocean has been the subject of much debate, and the placement of terranes in the Early Mesozoic remains a crucial part of this important discussion. Several continental terranes complicate the palaeogeographical reconstruction. One such terrane is Crockerland, which has been inferred to explain sediment distribution in the Arctic throughout the Mesozoic. However, Triassic successions throughout the Arctic basins bear many similarities, and a common sedimentary source could offer a simpler explanation with fewer complications for the past configuration of the Arctic. The study's goal is to test the hypothesis of long-distance sediment transport from a common source in present-day Russia to all Arctic basins in the Triassic, and to demonstrate how estimates of sediment routing distances can improve pre-break-up plate-tectonic reconstructions. Results confirm that (1) the Arctic basins were closely connected prior to break-up in the Mesozoic, (2) based on regional facies distribution, sediment budgets, sediment modelling and detrital zircon age spectra, the Crockerland terrane is unlikely to have existed as a major sediment supplying area, (3) the reconstructed Arctic sediment routing system can help to constrain plate-tectonic models, and (4) statistical estimation of sediment transport is a novel and potentially important tool for improving plate-tectonic and palaeogeographical reconstructions. Supplementary material : A database for provenance study, detrital zircon age spectra and the sedimentary length calculations method are available at https://doi.org/10.6084/m9.figshare.c.6086468

Sediment provenances of a Mesozoic intracontinental basin enclosed by multiple orogenic belts, Junggar Basin, NW China: insights from detrital ilmenite, Cr-spinel geochemistry, and zircon U–Pb geochronology

ABSTRACT The Junggar Basin was an intracontinental basin enclosed by multiple orogenies in the Mesozoic. Unravelling the provenances development in the western Junggar Basin enclosed by the West Junggar Orogenic Belt (WJOB) and Tianshan Orogenic Belt (TSOB) would elucidate the exhumation history of these orogenic belts during the post-orogenic period. The TSOB includes Central Tianshan which includes a continental block with the Precambrian to early Palaeozoic metamorphic basements, while the WJOB includes Palaeozoic accretionary complexes. Given their contrasting geological histories, we use detrital garnets, metamorphic ilmenites, epidotes, and Precambrian zircons to distinguish the TSOB and detrital Cr-spinel to distinguish the WJOB. Combined with sedimentary analysis, palaeocurrents, heavy mineral data, seismic profiles, and zircon U-Pb geochronology, here we reconstruct a four-phase source-to-sink model. During the syn-rift phase, the southern basin was stably fed by the TSOB in the Triassic, evidenced by high Garnet-zircon index and stable single-peak Carboniferous detrital zircon age spectra. During the post-rift sag basin phase, the source-to-sink system experienced a significant change, because detrital zircon age spectra change into multiple peaks. During the transpressional basin phase, the WJOB replaced the TSOB as the dominant provenance in the late Middle Jurassic and the TSOB became the dominant provenance again in the Late Jurassic. Syndepositional volcanic materials provided a large amount of sediments. During the sag basin phase, lake transgression happened and the TSOB provenance could not reach the northern basin. We concluded that the WJOB experienced transpression and obvious denudation in the late Middle Jurassic, and the TSOB uplifted under transpression in the Late Jurassic. The transpression controlled the change of major provenances. The aridification in the Late Jurassic was recorded by the decrease in the Zircon-Tourmaline-Rutile index and the increase in epidotes and magnetites. The humidification in the Early Cretaceous was responded to by lake transgression and sediment recycling.

A Laurentian affinity for the Embu Terrane, Ribeira Belt (SE Brazil), revealed by zircon provenance statistical analysis

New and compiled detrital zircon U–Pb ages from the southern Neoproterozoic–Cambrian Ribeira Belt, SE Brazil, demonstrate Laurentian affinity of the Embu Terrane which is statistically distinct from the adjoining Apiaí and São Roque terranes with cratonic affinity (e.g., São Francisco Craton). Zircon provenance results indicate that the type-area of the Embu Terrane is dominated by detrital zircon age modes at ca. 1200 Ma, 1400 Ma, and 1800 Ma, with maximum depositional age of ca. 1000 Ma. In contrast, the Apiaí and São Roque terranes are dominated by Paleoproterozoic detrital zircon ages (ca. 2200–2000 Ma age dominant component), with maximum depositional ages of ca. 1400 Ma and 1750 Ma, respectively. Multidimensional scaling (MDS) analysis of non-parametric similarity measurements on zircon age populations indicates for the first time that the Embu Terrane encompass two statistically distinct detrital zircon age spectra, which is also reflected in the metamorphic zircon age record. The statistical characterization of the Embu Terrane through populational metrics allow a quantitative comparison with surrounding tectonic domains and rock samples classified such as Embu-type. Our results clearly highlight the distinction between the statistically differentiated Embu Terrane from the Apiaí and São Roque terranes, supporting an allochthonous interpretation. In addition, we demonstrate that rocks samples previously classified as Embu-type are significantly dissimilar to the definition of Embu Terrane, failing to support alternative tectonic models (e.g., intracontinental evolution). Detrital zircon age spectra reveal that the Apiaí and São Roque terranes have similar zircon provenance to domains sourced from the São Francisco Craton, whereas detrital zircon populations from the Embu Terrane have greater affinity with SW Laurentia basins (and their inferred sediment sources), consistent with previous findings. Therefore, we interpret the Embu Terrane as a Rodinia descendant developed along the active margin of the SW Laurentia that collided with the Ribeira Belt during early Neoproterozoic (810–760 Ma).

Quantifying the Link Between the Detrital Zircon Record and Tectonic Settings

AbstractFull‐plate reconstructions describe the history of past continental motions and how plate boundaries have evolved to accommodate these motions. Traditionally, tectonic reconstructions relied on geophysical data from the oceans and paleomagnetism as the primary quantitative constraints. However, these data do not directly constrain the paths of subduction zones or other plate boundaries, so reconstructing the complete configurations of tectonic plates in the past must rely on alternative methods. Here, we investigate the applicability of detrital zircon age spectra to characterize tectonic settings in deep time using a much larger data set than previously considered. We analyzed the proximity between reconstructed plate boundaries and sample sites assigned to different tectonic categorizations based on the proportion of zircon ages close to the depositional age and found that the categorization has an ∼70% success rate in distinguishing convergent settings. Results are not strongly influenced by factors such as the number of zircon grains available within each detrital sample or uncertainty in the depositional age of the sample. The ability of the categorization to define extensional settings, such as rift basins, is less clear. Nonetheless, the broader pattern of results at the scale of Pangea shows that categorized zircon samples form a coherent pattern, where samples with dominantly young zircons lie at the supercontinent periphery while samples in the core of Pangea are dominated by grains much older than the age of deposition. This result suggests that zircon data could help to quantify uncertainties in full‐plate reconstructions and discriminate between competing models for Proterozoic supercontinents.

Western End of Late Cretaceous Fore-arc Basin and Provenance in SW Japan: Detrital Zircon U–Pb Dating of Upper Cretaceous–Paleogene Sandstones in Nagasaki-Nishisonogi Peninsula, Western Kyushu

Uranium–Pb ages of detrital zircons taken from seven sandstone samples collected at what were previously called “Paleogene strata” in the Nagasaki and Nishisonogi Peninsula, northwestern Kyushu, SW Japan are measured. Depositional ages of three sandstones in the Nagasaki peninsula are revealed to be e Campanian–Maastrichtian (Late Cretaceous) or younger. Depositional ages of two sandstones in Terashima Island off the west coast of the Nishisonogi Peninsula are likewise dated as Campanian or younger. By contrast, two sandstones in western Nagasaki Peninsula are confirmed as the Ypresian–Lutetian (Eocene) or younger. These new ages are concordant with sporadically reported mollusk fossils, basically supporting the previous stratigraphic scheme, except for a distinct Upper Cretaceous strata called the Mitsuze Formation. The age spectra of detrital zircons from the four Campanian sandstones share the same pattern; i.e., ranging in the Aptian–Campanian with a peak around the Cenomanian. The Maastrichtian sandstone has grains ranging in the Albian–Maastrichtian with a peak around the Turonian, which is slightly younger than that of Campanian sandstones. Judging from the dominance of Middle Cretaceous zircon grains, the main provenances of the sandstones are probably the Ryoke/San-yo and San-in granite belts in SW Japan, where Middle to Late Cretaceous felsic igneous rocks are extensively exposed. The age spectra of detrital zircons in the Campanian–Maastrichtian sandstones are almost identical to those of the Himenoura and Mifune groups in central Kyushu, and the Izumi Group in Shikoku/western Kii peninsula. All of these units were deposited unconformably over the Ryoke granitoids. Within the elongated arc-trench system extending for over 1,300 km from western Kyushu to northern Kanto, Mitsuze Formation sandstones in the Nagasaki-Nishionogi Peninsula mark the known western end of the large-scale Upper Cretaceous fore-arc basin in Japan.

Jurassic tectonics of northeastern Gondwana: evidence from the detrital zircon record of the Nambour Basin

The Nambour Basin provides the easternmost record of Jurassic sedimentation for Australia. U–Pb detrital zircon age spectra constrain basin infill as Early–Middle Jurassic ( c. 195–163 Ma). Early Jurassic samples are dominated by 650–500 Ma detrital zircon sourced from the Lachlan Orogen of southeastern Australia. Distal Jurassic upland associated with this orogen was generated by epeiric uplift. Sediment sourced from it was transported northwards and eastwards into the Nambour Basin as corroborated by basinal paleocurrent data. In contrast, Devonian to Triassic detrital zircon from the New England Orogen, which abuts the Nambour Basin margin, are scarce. Topographic relief across this orogen generated by the Permo-Triassic ( c. 260–230 Ma) Hunter Bowen Orogeny, had been largely eliminated by the Early Jurassic. Dominant Jurassic detrital zircon for one sample of this age, combined with related paleocurrent data and the absence of a Jurassic zircon source in eastern Australia, reflects an easterly Jurassic igneous assemblage now located on submerged northern Zealandia. The detrital zircon data presented herein constrains tectonic interpretations proposed for Jurassic east Gondwana, continental margin sedimentary assemblages in New Caledonia and New Zealand. Documentation of continental epeiric uplift from detrital zircon age data obtained from basin fill has potential yet to be explored. Supplementary material: Tables S1 and S2 are available at https://doi.org/10.6084/m9.figshare.c.5988017

Detrital-Zircon Geochronology of Jurassic–Cretaceous Strata in the Turpan-Hami Basin: Implication for the Late Mesozoic Tectonic Evolution of Eastern Tien Shan

Detrital-zircon U-Pb geochronology is extensively used to imply provenance histories as one of the most common methods to constrain the tectonic evolution of ancient sedimentary systems. The rapid accumulation of detrital-zircon thermochronology data in the eastern Tien Shan region brought great convenience for understanding the basin–mountain evolution in the region. In this work, 41 samples for zircon U-Pb dating from the Jurassic–Cretaceous strata of the Turpan-Hami basin and its adjacent region were compiled. Based on the systematic investigation, comparison, and summarization of Late Mesozoic sources in the eastern Tien Shan region and the quantitative characterization of source variations, we further explored and dissected the Late Mesozoic tectonic evolution of the eastern Tien Shan orogenic belt. Data from detrital-zircon age spectra, KS tests, MDS plots, Monte Carlo simulations, etc., suggested that eastern Tien Shan was also highly active during the Mesozoic, and especially, Bogda was the most remarkable. Moreover, there was a sig-nificant differential segmental exhumation before the Late Jurassic. In general, from the Early Ju-rassic to the Cretaceous, the proportion of Bogda provenance gradually increased, especially the large-scale uplift and denudation that occurred after the development of the Qigu Formation. The provenance of central Tien Shan and Jueluotag gradually stabilized before the Cretaceous. From the Late Jurassic to the Cretaceous, the decreasing tendency of the central-Tien-Shan-provenance percentages decreased, while that of Jueluotag provenance increased. Furthermore, central Tien Shan provenance had a slightly growing trend from the Early Jurassic (38%) to the Middle Jurassic (41.3%) and then gradually decreased to 20.3%. The Central Tien Shan still accounted for a sizeable proportion of the provenance, the genesis of which suggests that it may be that provenance as-cribable to central Tien Shan still crossed the poorly uplifted Jueluotag to the Turpan-Hami basin. Similar to central Tien Shan, the provenance ascribable to Jueluotag gradually decreased from an initial 51.8% to 14.9% in the Late Jurassic, but the proportion of the provenance increased again to 26% during the Cretaceous. These features opened the prelude to the Cenozoic tectonic activities in this region. In addition, the decomposition results revealed that the inverse Monte Carlo mixed model for dissecting the provenance of sandstone samples was subject to large biases in complex geological settings, such as detrital-zircon populations, the age spectra of source areas, contempo-raneous magmatism, and recovered older strata.

U–Pb detrital zircon geochronology and source provenance in the Moroccan Meseta (Variscan belt): A perspective from the Rehamna massif

Metasandstones from early Cambrian to early Carboniferous stratigraphic successions were sampled in the Rehamna massif of the Western Meseta in Morocco. The early Cambrian sample shows a single Paleoproterozoic population at ca. 2 Ga suggesting a local basement source. The Ordovician sample is largely dominated by a Cryogenian-Ediacaran population and minor Paleoproterozoic peaks. The Devonian sample reveals age populations similar to North-West African Cambrian to Devonian age spectra indicating that the southern-derived West Gondwana source essentially pertained up to the Devonian. The two early Carboniferous samples show more heterogeneous zircon age spectra with a marked Ediacaran peak accompanied by Paleoproterozoic and Mesoproterozoic sub-peaks indicating important re-organization of the drainage systems. One sample also shows presence of Upper Devonian to early Carboniferous zircon grains, which suggests local magmatic sources associated to the formation of intracontinental extensional basins. The comparison of detrital zircon spectra with paleogeographic reconstructions indicate that the early Carboniferous change in detrital zircon sources can be interpreted in the framework of the opening of the Paleotethys ocean with coeval erosion of orogenic topographies linked to the emplacement of a Mid-Variscan Allochthon, and/or collision of an Avalonian indenter to the north.

Late Neoproterozoic-early Paleozoic tectonic evolution and paleogeographic reconstruction of the eastern Tibetan Plateau: A perspective from detrital zircon U–Pb-Hf isotopic evidence

The Yidun Terrane, sandwiched between the Qiangtang and Songpan-Ganze terranes, hosts important information on the tectonic evolution of the eastern Tibetan Plateau. However, its tectonic link with adjacent terranes and East Gondwana remains equivocal. Here, we present U-Pb-Hf isotopes of detrital zircons from the upper Neoproterozoic-lower Paleozoic clastic rocks in the Yidun Terrane. The results show that detrital zircons from the Neoproterozoic rocks are mainly of ca. 821 – 890 Ma, 1714 – 1977 Ma, and 2317 – 2520 Ma, with εHf(t) values of each group comparable to coeval magmatic rocks in the nearby South China Block. This suggests that the Yidun Terrane and South China were possibly connected in the late Neoproterozoic, with the latter being the main sedimentary provenance. In contrast, the five Paleozoic samples have markedly different detrital zircon age spectra at ca. 2600 – 2300 Ma, 1100 – 900 Ma, 900 – 740 Ma, and 690 – 480 Ma, which were interpreted to have derived from Pan-African and Grenville-age provinces in the East Gondwana, as well as the South China Block and Songpan-Ganze Terrane. Such a major change on provenance suggests that after prolonged isolation in the Proto-Tethys, the Yidun Terrane began to collide with the East Gondwana in late Ediacaran to early Paleozoic. Integrated with published works, we consider that the Yidun Terrane, along with Songpan-Ganze Terrane and Yangtze Block, was located on the northern margin of East Gondwana during the early Paleozoic.

Where did the Kontum Massif in central Vietnam come from?

The Kontum Massif (KTM) is the largest Precambrian basement exposure in the Indochina Block, Southeast Asia. The compositions and formation ages of the KTM basement rocks and the paleo-position of the KTM in Proterozoic supercontinents have not been well constrained. Zircon U-Pb-Hf isotopic data of sixteen samples from the KTM in this study indicate that the KTM basement consists mainly of different units of metasedimentary rocks. These sedimentary rocks were deposited in five periods, late Paleoproterozoic (G1, 1.80–1.65 Ga), late Paleoproterozoic - early Mesoproterozoic (G2, 1.74–1.45 Ga), Mesoproterozoic (G3, 1.4–1.1 Ga), late Mesoproterozoic - early Neoproterozoic (G4, 1.1–0.81 Ga), and late Neoproterozoic - early Paleozoic (G5, 0.61–0.51 Ga), and underwent three phases of metamorphism in the early Paleozoic (501–415 Ma), late Paleozoic (371–331 Ma), and Indosinian (272–235 Ma). The G1 and G2 sedimentary rocks have abundant Neoarchean (2.63–2.48 Ga) and late Paleoproterozoic (1.83–1.74 Ga) detritus, and the G3 and G4 sedimentary rocks consist mainly of late Paleoproterozoic (1.74–1.72 Ga) and middle Mesoproterozoic (1.41–1.35 Ga) clastic materials. The G5 sedimentary rocks are characterized by consecutive Mesoproterozoic detrital zircon age spectra with a wide age peak at 1.06–1.01 Ga, much different from the G1 to G4 sedimentary rocks. Most Archean detrital zircons show juvenile Hf isotopes, whereas late Paleoproterozoic, middle Mesoproterozoic, and Grenvillian zircons show large Hf-isotope variations. Most detrital zircons are exotic because coeval igneous rocks have not been identified in the KTM (or elsewhere in Indochina), except ∼1.44 Ga ones.Comprehensive comparisons of detrital zircon U-Pb, Hf isotopes and sedimentary environments of these five units of sedimentary rocks with the extensive magmatism and coeval siliciclastic rocks in different cratons and microcontinents suggest that most of the Precambrian sediments in the KTM were derived from southwestern Laurentia, and the KTM has maintained a long-time connection with southwestern Laurentia for about one billion years from the G1 to the G4. The KTM was adjacent to Hainan Island and Tasmania during the G3-G4 deposition. The U-Pb ages and Hf isotopes of detrital zircons and sedimentary environment of the G5 sedimentary rocks indicate that the KTM was located on the northern margin of East Gondwana and near South China, India and western Australia, consistent with previous configurations for the Indochina Block. Therefore, the KTM, together with South China and Hainan Island, experienced quick northward movement from southwestern Laurentia to the northern margin of East Gondwana during the G4 (ca 1.10–0.81 Ga) to the G5 (0.61–0.51 Ga), which is also supported by new paleomagnetic data.

Paleo-Mesoproterozoic magmatic-sedimentary events in eastern Bainaimiao micro-block: Implications for Precambrian tectonic evolution of a fragment from Columbia supercontinent

Identifying tectonic positions and origins of Precambrian micro-blocks within the Central Asian Orogenic Belt (CAOB) is essential for revealing global paleogeography and evolution of the early Earth. The Bainaimiao micro-block in the southeastern CAOB preserves multistage geologic records which can better reveal Precambrian tectonic history of micro-blocks within the Phanerozoic accretionary orogenic belt. This study presents integrated research of geochronology, geochemistry, and zircon Hf isotopes on the Chenjiatun metamorphic complex in the eastern Bainaimiao micro-block, which consists of meta-sedimentary rocks (plagioclase gneisses and mica schists), amphibolites and two-mica granites. The protoliths of amphibolites, two-mica granites and meta-sedimentary rocks were formed at 1.75 Ga, 1.38 Ga and 1.39–1.34 Ga, respectively, suggesting that they represent Paleo-Mesoproterozoic basement of the Bainaimiao micro-block. The detrital zircon age spectra of meta-sedimentary rocks show two representative age peaks at 1.80 Ga and 1.40 Ga, with zircon Hf isotopes varying from −11.11 to +10.67. Characteristic mostly positive zircon Hf isotopes and geochemical features of the Chenjiatun complex indicates that the Bainaimiao micro-block probably has tectonic affinity with the Laurentia-Baltica continent. Paleoproterozoic amphibolites with positive εHf(t) (+5.67 to +15.42) were derived from metasomatized mantle wedge mixed with sediment melts. They are characterized by arc-like geochemistry such as high Th/Yb (0.73–2.77), enrichment in LILEs and depletion in HFSEs (eg. Nb and Ta), similar to coeval arc magmatism in the Laurentia-Baltica continent, which indicate the Bainaimiao micro-block was possibly in a subduction convergent setting in the late Paleoproterozoic. By contrast, Mesoproterozoic two-mica granites, with mostly positive εHf(t) (−0.29 to +11.53), belong to typical S-type granites and could be generated from partial melting of meta-pelites with participation peritectic garnets. These two-mica granites, together with ∼1.40 Ga juvenile A-type grantioids from nearby and other Precambrian micro-blocks in the southern CAOB, exhibit relatively high alkalis and HFSEs contents, young Hf model ages (1.50–1.40 Ga) and were generated at high-temperature environment. These findings reveals that the Bainaimiao micro-block was in an extensional setting at 1.40 Ga coeval with the breakup evolution of the Columbia supercontinent.

Provenance of Early Late Ordovician marine carbonate red beds in the Tarim Block and implication for tectonic evolution of northern Gondwana

As the largest oil-bearing basin in northwest China, the Tarim basin records multiple major tectonic-sedimentary transitions during the Early Paleozoic, which play an important role in understanding assembly processes of Gondwana. An important transition from the Middle to Late Ordovician was development of important unconformity T74, the end of a unified carbonate platform, and development of turbidites in eastern basin. However, due to unobvious terrigenous clastic record, there is still a lack of understanding of driving mechanism of the tectonic transition. Marine carbonate red beds (MCRBs) with detritus components are developed in the Tumuxiuke/Kanling Formation at the bottom of the Upper Ordovician. By detailed field observation, zircon U-Pb dating and Hf-isotope analyses, provenance and the tectonic implication of the MCRBs are studied. New zircon U-Pb dating results constrain the depositional age of the MCRBs at ca. 454Ma. Provenance tracing shows the Precambrian detrital zircons were mainly sourced from the basement of the Tarim block, and the early Late Ordovician detrital zircons were probably derived from ash from the Altyun Tagh orogenic belt. Based on syn-depositional magmatic zircon records and the magmatic-metamorphic records in the Altyn Tagh orogenic belt, the closure age of North Altyn Ocean, one branch of Proto-Tethys Ocean, can be constrained to the latest Middle Ordovician (~ca. 460 Ma). The collison of the Tarim block with the Central Altyn terrane occurred (ca. 460 Ma - 454 Ma), leading to the major tectonic-sedimentary transition in the Tarim block. The U-Pb age spectrum of detrital zircons also indicates that the Tarim block is closely related to the North Indian block in Gondwana. This study shows that carbonate rocks with low clastic flux can be applied as provenance research objects.