Detrital Zircon Research Articles

Sediment composition and U–Pb ages of detrital zircons in the Salina Cruz and Puerto Ángel beaches along the Gulf of Tehuantepec, Mexican Pacific

The Salina Cruz and Puerto Ángel beach areas in the Gulf of Tehuantepec, Mexican Pacific coast represent an important economic sector of the region. In this study, the mineralogy and geochemistry of bulk sediments, and geochronology of 400 detrital zircons recovered from the beach sediments were analysed to investigate their origin. The sediments are abundant in quartz, feldspar, ilmenite, cordierite, aragonite and anorthite. The chemical index of weathering revealed a moderate to intense weathering in the source area. The chondrite normalized REE patterns of bulk sediments are similar to the found in the Upper Continental Crust, suggesting the derivation of sediments from felsic igneous rocks. The REE patterns of zircons and the trace elemental ratios reveal a continental crust origin. Zircon U–Pb ages in the Salina Cruz beach were represented by Proterozoic (~545.1–1314.1 Ma; n = 170) and Cenozoic (~0.01–66 Ma; n = 20). The Puerto Ángel beach was abundant in Proterozoic zircon grains (~600.9–1171.4 Ma; n = 109) and followed by Mesozoic grains (~73.78–246.9 Ma; n = 40). The comparison of zircon U–Pb ages of this study with probable source rocks reveals that the Oaxaquia Terrane and Chiapas Massif Complex were the major contributors of Proterozoic zircons to the coastal areas. Similarly, the results indicate that the Cenozoic zircons were contributed by the Chiapas Massif Complex, coastal batholith and Cuicateco Terrane. The Mesozoic zircons are very few, derived from the nearby Xolapa Complex and the Chuacús Terrane.

Provenance evolution of the Fushan Sag (Hainan Island, Southern China): Constraints from U-Pb geochronology on detrital zircons

The Fushan Sag, situated on the southeast of the Beibuwan Basin in the northern Hainan Island, represents a semi-graben fault sag, characterized by a near NEE trend. In this study, we conducted LA-ICP-MS U-Pb age dating on detrital zircon from both the Liushagang and Weizhou formations in the Fushan Sag. By integrating our findings with previous research and considering the geological characteristics and bedrock conditions of the surrounding areas, we aimed to ascertain the provenance of the Fushan Sag. The obtained detrital zircon ages (1059 with 80% concordance) can be primarily categorized into three distinct age groups: Mesozoic (90–250 Ma), Paleozoic (250–450 Ma), and Proterozoic (450–2500 Ma). Specifically, detrital zircon grains from the Weizhou Formation reveal three prominent age peaks, approximately falling within the ranges of 100–150 Ma, 250–300 Ma, and 400–450 Ma. Conversely, the detrital zircon grains extracted from the Liushagang Formation predominantly exhibit two age peaks, approximately spanning 100–150 Ma and 200–300 Ma, with a weaker peak observed at 350–450 Ma in the second member, implying a potential change in provenance during this period. A comparative analysis of detrital zircon age characteristics strongly suggests that the primary provenance of the study area is Hainan Island, with the possibility of contributions from the YunKai Massif. Base on the preliminary geochronological data gathered, and in conjunction with extant scholarly research, an inference can be formulated regarding the paleogeographic evolution of the Beibuwan Basin spanning from the Eocene to the Oligocene. This analysis offers insights into the basin's geological history and dynamic changes over this extensive time frame.

Magmatic and sedimentological arguments for an Ediacaran active margin in the Bayankhongor Zone in western Mongolia, Central Asian Orogenic Belt

Geochronological and geochemical investigation of the magmatic and sedimentary rocks from the south-eastern tip of the Bayankhongor Zone (central Mongolia) constrains the Neoproterozoic evolution of the northern margin of the Baidrag Block. There, ultramafic to felsic igneous rocks of the Khan-Uul Massif intruded the volcano-sedimentary sequence of the Ulziit Gol Unit. U–Pb zircon ages show that both the plutonic and volcanic rocks were coeval products of the same Ediacaran (598–564 Ma) magmatism. Most of the samples have low contents of high field strength elements typical of arc-related magmas; however, some mafic rock samples display N-MORB-like chemistry. Magmatic rocks in the Khan-Uul Massif and Ulziit Gol Unit yielded exclusively positive initial εHf in zircon values (+4.9 to +13.8), implying derivation from depleted-mantle sources. Furthermore, heterogeneity of the whole-rock initial εNd values (–4.0 to +2.1) documents that fractional crystallization was accompanied by variable crustal contamination. The detrital zircon age patterns of the sandstone and tuffites in the Ulziit Gol Unit indicate that the sequence was filled dominantly by Ediacaran magmatic detritus derived from the Khan-Uul Massif and its volcanic equivalents, while the older cratonic material from the Baidrag basement represented only a subordinate component. Combined magmatic and sedimentary records imply that both the Khan-Uul Massif and the Ulziit Gol Unit may have formed in the same back-arc basin environment. This challenges the previous view that the entire Bayankhongor Zone was ophiolitic in nature. Distribution of coeval Ediacaran supra-subduction systems on the scale of the Mongolian Collage indicates the closure of multiple oceanic basins rimming the Siberian Continent. Following Rodinia break-up, this peri-Siberian realm was presumably formed by sub-parallel continental ribbons and oceanic basins. It is proposed that the amalgamation of these blocks and closure of intervening oceans reflected the Ediacaran advancing mode of the Palaeo-Pacific subduction.

Peri-Gondwanan sediment in the Arkoma Basin derived from the north: The detrital zircon record of a uniquely concentrated non-Laurentian source signal in the late Paleozoic

Peri-Gondwanan sediment in the Arkoma Basin derived from the north: The detrital zircon record of a uniquely concentrated non-Laurentian source signal in the late Paleozoic

Reply to ‘how not to use U–Pb detrital zircon geochronology to infer regional tectonics: Comment on , Journal of African Earth Sciences, 104942’ by Rajesh et al

Reply to ‘how not to use U–Pb detrital zircon geochronology to infer regional tectonics: Comment on , Journal of African Earth Sciences, 104942’ by Rajesh et al

Neoproterozoic transition from subduction to breakup along the margin of the Rodinia supercontinent: Sedimentary evidence from the northwestern Tarim Block, Northwest China

The Tarim Block, northwest China, was positioned on the periphery of Rodinia during the Neoproterozoic Era, and preserves a geological archive chronicling the assembly and breakup of the supercontinent. Due to its antiquity and limited exposure, sedimentary records along the margin of the Rodinia supercontinent remain sparsely documented. This study focuses on the Xifangshan and Dongqiaoenbrak formations, the oldest sedimentary units in the northwestern Tarim Block, which comprise a Neoproterozoic sedimentary record at the supercontinent margin during the transition from subduction to breakup. A comprehensive analysis employing sedimentology, petrology, elemental geochemistry, and UPb detrital zircon chronology was undertaken, to elucidate paleoenvironment, parent rocks, and tectonic-sedimentary evolution. Findings show that the Neoproterozoic witnessed the subduction of an oceanic plate beneath the Tarim Block, resulting in the formation of a continental margin magmatic arc. The Xifangshan Formation, deposited during the late phase of this arc (with the earliest sedimentary age recorded at 770 Ma), represents a submarine fan dominated by turbidity currents. Around 760 Ma, rapid crustal uplift occurred, and the tectonic setting gradually shifted from subduction to rift, giving rise to the coastal alluvial fan sedimentary system observed in the Dongqiaoenbrak Formation. Both the Xifangshan and Dongqiaoenbrak Formations record deposition in an oxic to suboxic marine environment with moderate salinity, influenced by a semiarid to semihumid palaeoclimate. The continental margin arc served as the primary source for sedimentation in both formations, and a few magmatic products linked to extension (syenite, monzonite) were also cannibalized into the sedimentary system of Dongqiaoenbrak Formation. This transition from a turbidite system to a coastal alluvial fan represents a sedimentary response to the subduction-to-breakup dynamics along the margin of the Rodinia supercontinent.

Evidence for, and significance of, the Neoproterozoic Xuefeng Orogeny, South China

The recognition of unconformities is important for determining the long-term evolution of orogenic belts. We document an unconformity between Tonian and Cryogenian strata of the Nanhua Basin of South China. This stratigraphic break has previously been termed the Xuefeng Movement and is developed within the Yangtze Block and western Cathaysia Block. Deformation characteristics and detrital zircon U-Pb geochronology from rock units underlying and overlying the unconformity (i.e., the Niuguping and Gucheng formations, respectively) from the Anhua region of the northern Hunan Province in the southeastern Yangtze Block are documented. The Niuguping Formation displays a set of top-to-northwest imbricate thrust faults and related fault-propagation folds, NEE-plunging subparallel crenulation lineations, a foliation, and shows widespread greenschist facies metamorphism. In contrast, the overlying Gucheng Formation exhibits no obvious stratal deformation (apart from a mild inclination of bedding) and is unmetamorphosed. Detrital zircon age spectra of the samples from the Niuguping Formation are characterized by unimodal age peaks of ca. 750–730 Ma, while those of the samples from the Gucheng Formation yield a multimodal age distribution, with a few syn-sedimentary detrital zircons (<700 Ma), and much older zircons with age peaks of ca. 800 Ma, 2.1–1.9 Ga, and 2.6–2.3 Ga. Combining this data with previous geochronology indicates deposition of the Niuguping and Gucheng formations in the late Tonian (725–720 Ma) and Cryogenian (690–660 Ma), respectively. The time gap across the unconformity is some 30 Ma (720–690 Ma). The unconformity and associated structural and metamorphic break extend across the Yangtze Block and western Cathaysia Block, defining a major regional orogenic event. The significantly different detrital zircon spectra of strata across the unconformity suggest a dramatic change in the source due to the Xuefeng Orogeny in the Yangtze Block. Zircon U-Pb-Hf isotopic evidence indicates that detritus of the Niuguping Formation below the unconformity was derived from syn-depositional magmatic activity in the northern Yangtze Block, while a significant increase of Archean to Paleoproterozoic ages for the Gucheng Formation, suggests that the Xuefeng Orogeny resulted in crustal thickening and denudation in the northern Yangtze Block. These changes in provenance, along with changing deformational and metamorphic patterns, indicate evolution of the Nanhua Basin from a compressional to an extensional back-arc basin, which we infer is related to tectonic switching from an advancing to a retreating subduction system in the northern Yangtze Block at the time of the unconformity.

Early-stage intracontinental rifting in the Neoproterozoic Centralian Superbasin: Systematic U–Pb and Lu–Hf isotopes in detrital and inherited zircons from the Yeneena Basin, northwest Australia

Detrital zircons from different lithostratigraphic units of Supersequence 1 across the Neoproterozoic northwest Officer and Yeneena basins were investigated using LA-ICPMS U−Pb and Lu − Hf isotope analyses to understand the source of detritus and potential links to regional tectono-magmatic events, as well as the crustal evolution of the sedimentary sources terranes. All data show that Proterozoic detritus dominate the age spectra of samples from the Yeneena Basin and northwest Officer Basin, with signatures varying in the heights of peaks rather than the presence or absence of age groups in different formations. The Archean and Proterozoic ages overlap with known magmatic events in the Pilbara Craton, Fortescue Basin, Rudall Province, Capricorn Orogen, Musgrave Province, Madura Province, and the Coompana Province suggesting these terranes are possible sources of the detritus. The detrital zircon population of the samples have main age peaks in the range 1300 to 1000 Ma, suggesting magmatic rocks of the Rudall and Musgrave provinces are the main sources of detrital zircons, which can be differentiated by Hf signature. The distal Musgrave Province persistently dominates the provenance of detritus in the northwestern Officer and Yeneena basins, while detritus from the proximal Rudall Province contributes to a lesser extent. This suggests that the distal Musgrave Province remained emergent during the evolution of the northwestern Officer Basin and the Yeneena Basin, whereas the proximal Rudall Province potentially became buried by the accumulating sedimentary rocks and contributed less detrital zircons. The 833.6 ± 1.4 Ma maximum depositional age obtained in this study for the sedimentary rocks of the northwestern Officer and Yeneena basins point to the approximate time of the start of basins development. The extensional event in this age period is related to emplacement and extrusion of the ca. 830 Ma Willouran Large Igneous Province (LIP). The Duke gabbro sills observed in the Yeneena Basin are part of this LIP, which extends from the Adelaide Rift Complex, through the Musgrave Province, central–northwest Officer Basin and into the Yeneena Basin. The sediment source terranes suggest a southeast–northwest oriented depositional system between central and Western Australia, possibly because of intracontinental rifting related to widespread mafic–ultramafic magmatic events that could include the earlier Ngaanyatjarra Rift formed by the 1090–1040 Ma Warakurna LIP as well as the ca. 830 Ma Willouran LIP, synchronous with the breakup of Rodinia in the mid-Neoproterozoic.

Provenance of cretaceous sediments in the West Kunlun piedmont belt and implications for tectonic evolutionary events

The West Kunlun orogenic belt located in the northwestern margin of the Qinghai-Tibet Plateau is an important record of the formation and northward extension of the plateau, but the current research mainly focuses on the tectonic activities of the Cenozoic era, and there is still considerable controversy regarding the formation and evolutionary history of pre-Cenozoic orogenic belts. This study focuses on Cretaceous sandstone samples from the Kedong region in the piedmont belt of the West Kunlun orogenic belt. U-Pb geochronological analysis was performed on 200 detrital zircon grains from the core samples. Combined with stratigraphic data and previous research, the main provenance direction was investigated to constrain the tectonic evolutionary history of the orogenic belt’s peripheral regions. The results show that the detrital zircons are aged from 290 to 208 Ma, 520–310 Ma, 810–580 Ma, 1,400–880 Ma and 2,548–1,730 Ma, reflecting the complexity of provenance in this area. Based on a comprehensive analysis of the characteristics of igneous rocks, zircon age composition and stratigraphic conditions in potential source areas, it is concluded that the primary source regions include the East Kunlun orogenic belt and the North and South Kunlun terranes, with a low likelihood of contributions from within the Tarim Basin. The evolution of the West Kunlun orogenic belt can generally be divided into two opening and two closing phases. The detrital zircon ages predominantly exhibit two peak values at 259 Ma and 459 Ma, respectively representing the ages of transition from oceanic crust subduction to continent-continent collision for the Paleo-Tethys Ocean and the Proto-Tethys Ocean. Additionally, there is a temporal gap between the evolution of the Proto-Tethys Ocean and the Paleo-Tethys Ocean. The Triassic period marks a transitional phase in tectonic evolution, shifting into an intracontinental evolutionary stage. This study provides new geochronological evidence for the early developmental history of the West Kunlun orogenic belt.

Heavy Mineral and Zircon Age Constraints on Provenance of Cenozoic Sandstones in the Gulf of Mexico Subsurface

Combined heavy mineral analysis and detrital zircon geochronology have enabled us to track detritus supplied by the ancestral river systems draining the North American continent into the deep subsurface of the Gulf of Mexico, in both the coastal plain and the offshore deep water areas. During deposition of the Paleocene–Eocene Wilcox Group, sandstones in the western part of the area are interpreted as the products of the Rosita system derived via paleo-Rio Grande material, with a large component of sediment shed from the Western Cordillera. By contrast, samples from wells further east have high proportions of zircons derived from the Yavapai-Mazatzal Province and are attributed to the Rockdale system with sediment fed predominantly by the paleo-Colorado or paleo-Colorado-Brazos. There is evidence that sediment from the Rosita system occasionally extended into the central Gulf of Mexico, and, likewise, data indicate that the Rockdale system sporadically supplied sediment to the western part of the basin. During the Late Eocene of the central Gulf of Mexico (Yegua Formation) there was a distinct shift in provenance. The earlier Yegua sandstones have a large Grenville zircon component and are most likely to have had a paleo-Mississippi origin, whereas the later Yegua sandstones are dominated by zircons of Western Cordilleran origin, similar to Wilcox sandstones fed by the Rosita system via the paleo-Rio Grande. The switch from paleo-Mississippi to paleo-Rio Grande sourcing implies there was a major reorganisation of drainage patterns during the Late Eocene. Miocene sandstones in the deepwater Gulf of Mexico were principally sourced from the paleo-Mississippi, although the paleo-Red River is inferred to have contributed to the more westerly-located wells.

A revised stratigraphic model for the ∼ 1910–1835 Ma Tanami Group, the Northern Territory, Australia: Implications for exploration targeting

The Paleoproterozoic Tanami Group of the Granites—Tanami Orogen hosts a known endowment of > 20 Moz of gold mineralization across numerous deposits. Throughout the region, host lithologies impart a first-order control on the style, grade and endowment of mineralization. However, the genetic relationship and regional distribution of three regionally correlative formations (the Dead Bullock, Mount Charles and Stubbins formations) remains enigmatic. Here, we combine lithostratigraphic analysis, lithogeochemistry, detrital zircon geochronology and geophysical observations to propose a new evolutionary model for the Tanami Group. We find that the Tanami Group was deposited in a continental back-arc basin setting and developed in four stages. Package A marked the onset of the rifting of the continental Archean basement. Sedimentary rocks within Package A are dominantly felsic in composition and display a unimodal detrital zircon age population at ∼ 2530 Ma. Package B marks the onset of mafic volcanism; consequently, volcaniclastic and sedimentary rocks within Package B display a distinct mafic geochemical signature. Detritus shed from an Archean basement persisted throughout this period, and a unimodal detrital age component at ∼ 2530 Ma persists. Package C marked the waning stages of voluminous mafic volcanism across the Tanami Basin. Sedimentary volcaniclastic rocks within Package C display a mixed mafic and felsic composition. Detrital zircon age spectra record multiple peaks at ∼ 2500, 3000 and 3350 Ma, which may reflect erosion of older Archean basement domains or changes in paleo-drainage. Package D marked a significant change in the source of detritus entering the basin from dominantly Archean to Paleoproterozoic, with dominant detrital age peaks at ∼ 1860 Ma. Despite significant lithofacies variations, the presented model highlights multiple correlations between the Dead Bullock and Mount Charles formations. The Mount Charles Formation likely represents a volcanic source-proximal, high-energy depocenter. In contrast, the Dead Bullock Formation was deposited in a lower energy setting, distal to volcanic centers. These observations are important to mineral exploration. Notably, the Mount Charles Formation is distributed over a significantly greater area than previously thought, and the under-represented Hangingwall and Footwall sequences of this formation are interpreted to host significant gold mineralization at the Oberon and Groundrush deposits.

Zircon Internal Deformation and Its Effect on U-Pb Geochronology: A Case Study from the Himalayan High-Pressure Eclogites

Zircon, with a chemical formula of ZrSiO4, is a widely used mineral for determining the crystallization age of igneous rocks. It is also used to constrain the timing of metamorphic events from its overgrowth or recrystallized domains. Furthermore, detrital zircon grains can provide information on the sedimentary provenance. Due to the trace amounts of uranium (parent) which decays into its daughter element (Pb), it is a prime geochronometer for the majority of magmatic and metamorphic rocks. With high-precision analytical instruments, such as TIMS, SIMS, and LA-ICP-MS, huge amounts of geochronological and trace element data from zircon have been generated around the globe to date. Target domains within zircon grains are analyzed to extract geochemical and geochronological records using spatially resolved techniques such as ion probes or laser ablation coupled with mass spectrometry. Before any such analysis, the zircon grains are examined for internal structures, growth zoning, and the presence of tiny inclusions. However, many researchers analyze multiple domains within single zircon grains for U-Pb isotope analysis with little regard for their internal structures, particularly crystallographic orientations. Hence, they may obtain mixed ages with variable discordance, leading to imprecise interpretation especially when the growth domains are not well-identified. Particularly, zircon grains that contain multi-growth domains or have local internal deformations within a single grain may not produce geologically meaningful age results if the analyses are conducted on mixed domains. This study presents a brief review on zircon geochronology, how to identify and visualize micro-deformations in metamorphic zircons through the EBSD analysis, and the effects of micro-deformation on age results. Examples from a case study conducted on zircons hosted in the Himalayan high-pressure eclogites are presented that show intra-grain plastically deformed domains and their effects on the corresponding age results.

Late Paleozoic intra-oceanic arc and its accretionary complex in East Junggar (NW China): implications for multiple arc amalgamation in the southern Altaids

The East Junggar is a key to understanding the accretionary history of the southern Altaids. However, the tectonic setting and amalgamation history of the East Junggar during the Carboniferous–Permian remain controversial. Here we report new field, geochronological and geochemical data for the Carboniferous–Permian volcanic and sedimentary rocks from the Jiangjun unit and the Hongliugou ophiolitic complex of East Junggar to constrain its tectonic evolution. Carboniferous volcanic rocks, with zircon and apatite U–Pb ages from 337 ± 2 to 303 ± 32 Ma, display arc-related geochemical characteristics. Carboniferous–Permian sedimentary rocks predominantly contain Carboniferous–Permian detrital zircons and have maximum depositional ages from 318 ± 5 to 281 ± 6 Ma. Provenance analysis indicates that the sediments from the west Jiangjun unit were sourced from the Yemaquan arc and those from the east Jiangjun unit may be sourced solely from a new intra-oceanic arc. Integrated data indicate that Carboniferous–Permian strata in the Jiangjun unit were formed in the intra-oceanic arc setting that remained until the middle Permian. These analyses suggest an amalgamation process of multiple convergence and accretion for the southern Altaids during the formation of NE Pangaea in the late Paleozoic.

Carboniferous rifting of the Lhasa Terrane (Tibet, China) and the break-up of East Gondwana based on detrital zircon analyses

The break-up processes of the northern margin of East Gondwana remain uncertain, especially regarding the Lhasa Terrane. In this paper, we conduct a systematic field geological survey, detrital zircon UPb dating, and zircon trace element and Hf isotope analyses in the Carboniferous rift basin in the eastern part of the Lhasa Terrane, including the Nuocuo and Laigu Formations, to reconstruct the break-up history of East Gondwana. The overall Carboniferous depositional environment in the eastern part of the Lhasa Terrane changed from near-shore and shallow marine to slope and moderately deep sea facies, reflecting a transgression. The weighted average age of several of the youngest detrital zircons from the Nuocuo Formation is 346.8 ± 6.4 Ma (4 grains), whereas that of the Laigu Formation is 328.7 ± 6.1 Ma (6 grains). The detrital zircon ages in the Carboniferous strata show similar distributions, dominated by zircons from the Indian continent (∼950 Ma), Australian continent (∼1170 Ma), and Lhasa Terrane (∼340 Ma). The paleogeographic position of the Lhasa Terrane was near the Indian and Australian continents during the Carboniferous. The increase of the ∼340 Ma detrital zircon age peak from the Mississippian to the Pennsylvanian demonstrated that the rift basin recorded a Mississippian magmatic event. The εHf(t) and oxygen fugacity values of partial zircons of ∼340 Ma are similar to those of zircons from intraplate magmatic rocks, further implying the intracontinental rifting in the Lhasa Terrane. Combined with the previous research on magmatic rocks in East Gondwana, including the Lhasa, South Qiangtang, and Himalayan Terranes, our study on sedimentation found that the Lhasa Terrane was in a passive continental margin rifting context during the Mississippian and the rift gradually expanded to become the Sumdo Paleo-Tethys Ocean basin.

Geochronology (zircon U-Pb, Hf, O isotopes), provenance analysis, and tectonic setting of the Paleoproterozoic Karrat Group and supracrustal rocks of the Rinkian fold belt, West Greenland

We use zircon U-Pb, Hf and O isotopes to constrain the depositional ages and provenance of metasedimentary rocks of the Paleoproterozoic Karrat Group of West Greenland and to understand the tectonic processes leading to basin development on the eastern Rae craton. An older supracrustal assemblage (Qeqertarssuaq complex) deposited after ca. 2.6 Ga is separated by an unconformity with a younger supracrustal assemblage (the Karrat Group). The Qaarsukassak Formation at the base of the Karrat Group was deposited after ca. 2.0 Ga, with dominantly Archean age modes. The youngest siliciclastic rocks (Nûkavsak and Mârmorilik formations) in the Karrat Group have maximum depositional ages ranging from ca. 1980 to 1950 to 1900 Ma and contain dominant detrital zircon age modes between ca. 2.50 and 1.93 Ga. A ca. 1.92 Ga supracrustal assemblage referred to as the northern domain (Karrat Group, sensu lato) is geographically separated from the Karrat Group (sensu stricto) by the Prøven igneous complex. The stratigraphy and detrital zircon profiles are compared to broadly coeval sedimentary units on the Rae craton and a unifying model of their deposition is presented. The Rae craton is the dominant detritus source; initially these sources were mostly local, changing to a mix of local and distal sources including the western Rae craton. The tectonic setting of the Karrat basin transitioned from extensional to convergent to collisional during its basin evolution, reflecting Wilson cycle phases within an epeiric sea. Accordingly, zircon Hf isotopes in our dataset track the evolution of the opening and closing of the Manikewan Ocean. Detrital zircon Hf isotopes in our dataset reveal a greater proportion of juvenile detritus (especially ca. 2.15–1.95 Ga) than is known from the currently exposed crustal record, pointing to the importance of the detrital zircon record for understanding Paleoproterozoic crustal and tectonic evolution.

Revisiting zircon Eu anomaly as a proxy for crustal thickness: A case study of the Sierra Nevada Batholith

We analyzed detrital zircon from the Sierra Nevada Batholith, western USA, to reassess whether zircon Eu/Eu* can be used to reconstruct crustal thickness in the past. Our reconstruction shows two episodes of crustal thickening between 80–200 Ma in the Sierra Nevada region—one during the Jurassic (170—140 Ma) and the other in the Cretaceous (110—80 Ma). These findings are consistent with the results obtained using the whole-rock La/Yb proxy and observations on crustal deformation. Our results underscore the validity of zircon Eu/Eu* proxy for tracing the evolution of crustal thickness at the batholith or orogen scale, provided that a sufficient number of analyses are obtained. Recent petrologic models questioned the validity of the zircon Eu/Eu* proxy because of the complex interplay among various factors that may affect zircon Eu/Eu*. These models, however, overlooked the interconnections between these factors. In particular, magma redox condition and water content, which are known to significantly impact zircon Eu/Eu*, may also be controlled by differentiation pressure and thus crustal thickness. Therefore, rather than complicating the interpretation, these factors could potentially enhance the pressure control on zircon Eu/Eu*.

Channel evolution in the lower reach of palaeo Fen River: evidence from detrital apatite petrochronology and zircon geochronology

This study provides a comprehensive analysis combining multi-element (Sr, Y, Th, U and REE) geochemistry and U–Pb geochronology of single-grain apatite with zircon U–Pb ages from channel sand deposits of the palaeo Fen River, collected at the Chaizhuang and Weijiazhuang sites, corresponding to sediments from the Late Pleistocene and late Middle Pleistocene, respectively. The results unveil that the analysed apatites originated from a varied assemblage of source rocks, encompassing mafic–ultramafic rocks, intermediate to felsic I-type plutons, highly fractionated S-type granites and pegmatites, as well as assorted metamorphic rocks. U–Pb age dating of detrital zircons and apatites identifies three predominant age peaks at 2.4, 2.2 and 1.8 Ga, consistent with known tectonothermal episodes within the North China Craton (NCC). The similarity in U–Pb age spectra for both zircon and apatite, along with comparable apatite geochemical characteristics across both the Chaizhuang and Weijiazhuang sections, indicates stable provenance with little to no change from the late Middle Pleistocene to the Late Pleistocene. This continuity in provenance signatures suggests an absence of shift in drainage patterns or sediment sources, indicating that the current location and pattern of Fen River lower reach drainage was not formed at least by then. Consequently, it is inferred that the detrital material composing the palaeo Fen River sediments during this period predominantly originated from the NCC.

Significance of the Paleocene olistostrome–turbidite belt (Abant Formation) along the Intra-Pontide Suture, northern Turkey

A belt of Paleocene turbidites with olistostromes, the Abant Formation, crops out for 350 km along the Intra-Pontide Suture in northern Turkey. The suture constitutes the contact between two major Pontide tectonic units, the Istanbul and Sakarya zones, and the Abant Formation was used as evidence for the Paleocene–early Eocene closure of the Intra-Pontide ocean. We mapped and studied the Abant Formation along the Intra-Pontide Suture. The Abant Formation consists of deformed Paleocene siliciclastic turbidites with mass flows. The blocks in the olistostromes are mainly Late Cretaceous pelagic limestones; there are also Late Jurassic–Early Cretaceous, Late Cretaceous and Paleocene shallow-marine limestone blocks. Other rare block types include late Neoproterozoic and Permian granites, basalt, chert and serpentinite. The ophiolitic blocks make up less than 5% of the Abant Formation. Most of the blocks were derived from the south, from the Sakarya Zone; detrital zircon ages from the turbidite sandstones also indicate a predominantly southern source. The Abant Formation was deposited in a foreland basin, which was formed during the Paleocene collision between the Pontides and the Anatolide–Tauride Block. The basin was preferentially located on the Intra-Pontide Suture because the suture constituted an old crustal lineament.

New constraints on the Neoproterozoic geological evolution of the SE corner of the Arabian Plate (NE Oman)

The Saih Hatat Dome is a tectonic window in northeastern Oman with a NW–SE extent of c. 95 km and an east–west extent of c. 50 km, rimmed by the allochthonous Samail Ophiolite and the tectonically underlying nappes composed of sedimentary rocks from the Neo-Tethyan Hawasina Basin. Rocks within the window were affected by high pressure/low-temperature metamorphism during the latest Cretaceous. Stratigraphically, the Saih Hatat Dome contains a basal, several kilometre thick sequence, made up of low-grade metamorphic volcanosedimentary rocks (Hatat Formation). U–Pb zircon laser ablation inductively-coupled plasma mass spectrometry (LA-ICP-MS) data from a quartzdiorite dyke, intruding the basal part of the Hatat Formation yielded a crystallization age of 845 +2/−4 Ma, whereas zircons from a quartz keratorphyre have ages of 870 ± 5 Ma. Thus, the basal schists of the Hatat Formation are Tonian in age, similar to Tonian felsic volcanic rocks and a granodioritic intrusion in the Huqf area, 300 km to the south. Detrital zircons from the Hatat Formation show an age peak of 837 Ma with some Neoarchean and Paleoproterozoic grains, which have no potential source in the Arabian–Nubian Shield. Based on the new results, we propose that the Hatat Formation signifies a Tonian back-arc basin, contemporaneous with calc-alkaline igneous intrusions in the Jabal Ja'alan region. Similar calc-alkaline intrusions of comparable ages have been identified in the Mirbat area of Dhofar and the Huqf region in central eastern Oman. We interpret these outcrops as components of a cohesive island arc, characterized by calc-alkaline volcanic rocks and volcanosedimentary back-arc sedimentation. Our model situates these regions off the coast of NW India during the Tonian.

Vertebrates from the Late Miocene of Salinas Grandes de Hidalgo (central Argentina). New faunal data: biochronological and paleoenvironmental considerations

ABSTRACT Salinas Grandes de Hidalgo (La Pampa Province) is a relevant locality of the Cerro Azul Formation in central Argentina because of its abundant and diverse vertebrate remains, including representatives of Reptilia, Aves and mostly Mammalia. Concerning previous records, the present faunal list adds one Argyrolagidae marsupial, one Ctenomyidae and two Caviidae rodents, as well as the first detailed analysis and description of glyptodonts from the Cerro Azul Formation in La Pampa Province. New geological information is added about the two fossiliferous outcrops included in Salinas Grandes de Hidalgo area. The classically studied outcrop located in the saline lake and the nearby one in the so-called ex-Autódromo, both herein correlated based on lithostratigraphy, particularly by the presence of paleosols in the intermediate section of the sedimentary succession. These sandy silts deposits in the base of the outcrops indicate the development of poorly confined flows and intervals of surface stabilisation by paedogenesis. We offer a biochronological interpretation based on a recently published U-Pb detrital zircons dating (5.9 ± 0.4 Ma) and the presence of significant taxa such as octodontoid rodents recovered from the dated levels and below it. From a paleoenvironmental viewpoint, we infer variations from woodlands to open environments.