Detrital Zircon Data Research Articles

Locating the Yangtze Block in Nuna: Constraints from age and isotopic data from Paleoproterozoic sedimentary rocks in the Phan Si Pan Zone, northwest Vietnam

New U-Pb ages and Hf isotopic data for detrital zircons from the late Paleoproterozoic sedimentary rocks (Suoi Chieng Formation) in the Phan Si Pan Zone of northwest Vietnam constrain their depositional ages, provenance, and tectonic setting. The weighted average age of the youngest coherent zircon population is 1769 ± 31 Ma (MSWD = 1.3, n = 8), which provides a maximum depositional age for the Suoi Chieng Formation. The detrital zircons obtained from six Paleoproterozoic samples exhibit various ages, showing multiple magmatic and metamorphic events. The detrital zircon age pattern shows that magmatic activities in the source areas occurred at 2650 Ma, 2350–2150 Ma, and 2050 Ma, as well as minor activities at 2850 Ma, 1850 Ma, and 1780 Ma. Additionally, a prominent metamorphic age peak is observed around ca. 1850 Ma, while a few metamorphic zircons exhibit ages ranging from 2600 to 2500 Ma and 2100 Ma. This pattern indicates that the primary source of these zircons is the local basement rocks of the Phan Si Pan Zone and SW Yangtze. However, contributions from other adjoining cratonic blocks are also possible and these likely included the Rae craton of North Laurentia. Our new data verifies and expands earlier results, showing that the SW Yangtze and north Yangtze have distinct Archean-Paleoproterozoic crustal evolutionary histories prior to their assembly in the late Paleoproterozoic. Regional correlations based on detrital zircon spectra, stratigraphic and tectono-thermal histories show strong similarities between the SW Yangtze and the Rae craton of north Laurentia throughout the Paleoproterozoic, suggesting the proximity of the two blocks before or during the formation of the Nuna supercontinent. We further suggest that the north Yangtze adjoined southern Siberia in the Archean to late Paleoproterozoic as supported by their identical tectono-thermal histories and detrital zircon age spectra. In combination with published data, we propose that the Yangtze Block was located between north Laurentia and south Siberia during the Nuna assembly.

Neoproterozoic to early Paleozoic crustal growth, recycling, and the changing geodynamics of North Gondwana

Understanding crustal growth, reworking, and geodynamics of the northern continental margin of Gondwana during Ediacaran to Silurian times plays an important role in Gondwana's paleogeographic reconstruction. This study uses a combination of bulk-rock geochemistry, magmatic and detrital zircon geochronology, zircon trace element, and O-Hf isotope data to evaluate the Ediacaran-early Paleozoic magmatic history of northern Gondwana. Our detrital zircon data from Ediacaran to Ordovician sedimentary successions of central Iran show that the 620–500 Ma detrital zircon likely originates from the erosion of the Cadomian arcs in Iran and Anatolia. This zircon shows variable εHf(t) and δ18O values and Nb/Yb, U/Yb, and U/Nb, resembling arc rocks. The Cryogenian (1000–620 Ma) detrital zircon with juvenile εHf(t) and mantle-like δ18O values could have been supplied from erosion of the juvenile crust of the ANS. The youngest age peaks of 488–450 Mafor detrital zircon, in upper Cambrian-Ordovician sedimentary rocks, are considered to show the rifting of Gondwana and Paleotethys opening. Abundant unrounded 2.5 Ga detrital zircon from Ediacaran sandstones probably shows uplift and exhumation of a local source, i.e., the Archean crust of Iran. The Neoproterozoic igneous rocks formed firstly during the subduction of oceanic lithosphere (Mozambique Ocean) beneath northern Gondwana around 880 Ma to form the ANS juvenile crust. Later, the magmatism moved from the ANS toward the northern territories of Gondwana, with peak magmatism at 570–525 Ma. In Cambrian to Ordovician, the Cadomian magmatic arc was uplifted and eroded, and the geodynamic setting switched into juvenile magmatism following rifting of northern Gondwana.

A database of detrital zircon U–Pb ages in the North China Craton from the Paleoproterozoic to the early Palaeozoic

AbstractU–Pb dating of detrital zircon is widely used in geology to identify the source of sediments and constrain palaeogeography and tectonic history. We collected the detrital zircon from the Paleoproterozoic to early Palaeozoic strata to understand the North China Craton's geological chronological characteristics. After screening and sorting out data information, we managed and analysed 84 papers from 2006 to 2022. Three hundred seventy‐nine samples comprising 29,431 pieces of U–Pb ages of detrital zircons gathered from the Proterozoic to Ordovician sedimentary rocks in North China Craton (NCC). Detrital zircons within five areas in the NCC, i. e., Xuhuai Basin, Zhaertai‐Bayan Obo‐Huade Basin, Yanliao Basin, Xiong'er Basin and Alxa Block, are discussed in detail. Meanwhile, we collected 2,588 pieces of Lu‐Hf detrital zircon data in the study. This Database can be helpful in understanding and explaining the tectonic evolution of the NCC from the Paleoproterozoic to the Early Palaeozoic.

A synthesis of available detrital zircon data from Turkey, Cyprus and Greek peninsula

AbstractThis paper describes the assembly of an updated dataset of detrital zircon geochronology and Lu–Hf isotopes for Turkey, Cyprus and Greek peninsula. This first version of the dataset documented 286 samples with detrital zircon U–Pb data and 70 samples with zircon Lu–Hf isotopes from 42 published articles. These samples are mainly distributed in seven geologic‐tectonic units in the Eastern Mediterranean Tethyan region. The compilation of dataset will be periodically accessed in the Deep‐Time Digital Earth repository, containing more updated raw data of (un)published scientific research. We believe that the construction of such a dataset is fundamental to studies of clastic strata and also to understanding of crustal evolution in the Eastern Mediterranean region.

Three Generations of the Basins of the Early Turkestan Ocean: Ediacaran–Silurian of the Southern and Middle Tien Shan

The results of U–Pb dating of detrital zircon from volcanoterrigenous Ediacaran–Silurian deposits, mainly from grauwacke turbidites, after accretion of which the “Caledonian” basement of the Paleozoic structure was formed in Kyzylkum and in the ridges of the Southwestern Tien Shan, including Northern Fergana, allowed us to clarify the age correlation and show the dynamics of the formation of this complex. It consists of deposits associated with the opening, filling and subsequent convergent development of three generations of oceanic basins, including the emergence and destruction of island arcs. The earliest of these basins was formed at the active volcanic margin of the eastern Rodinia/Gondwana, which included the Karakum-Tajik massif. Sandy turbidites (Besapan, etc.), whose age is not younger than the beginning of the Cambrian, were deposited here on top of siliceous (Taskazgan) Ediacaran sediments. The second generation is represented by Ordovician basins, in which radiolarian flints of the Lower Ordovician form the bathyal part of the sediments, and the main filling is turbidites of the middle Ordovician–Ruddan. The newly opened Silurian oceanic basins and their margins were filled with sediments of the third Caledonian generation, mainly graptolite aleuropelites and turbidites, starting from the end of the Llandovery. Incomplete preservation of the Ediacaran–Silurian sedimentary series is due to their partial absorption (tectonic erosion) during further subduction and collision, mainly already in the Carboniferous.

Composition and Age of Sources of the Lower–Middle Cambrian (?) Terrigenous Rocks from The Ernichny Formation in the Argun Massif, Eastern Part of the Central Asian Fold Belt

The paper presents the results of the mineralogical and geochemical studies of sandstones and siltstones of the Ernichny formation of the Argun series in the Argun continental massif, and the results of U–Pb (LA‑ICP-MS) dating for the detrital zircons from these rocks. It is established that the youngest detrital zircons from sandstone of the Ernichny Formation have age of 549–570 Ma. A maximum on the relative probability curve of zircon age corresponds to 566 Ma. These data determine the lower age limit of their accumulation on the border of the Ediacaran and Paleozoic age. According to the results of U–Pb dating of detrital zircon, the majority of detrital zircons from sandstones of Ernichny Formation are characterized by Neo- and Paleoproterozoic ages. The sources of zircons were Neo- and Paleoproterozoic igneous and metamorphic rocks that were widely developed within the Argun continental massif. In turn, the geochemical features of the terrigenous rocks of the Ernichny Formation, together with the presence of the poorly sorted and rounded clastic material in the studied samples, as well as the presence of interlayers of gravelstones, enabled us to establish that they were formed in a subduction-related setting.

Structural and Geochronological Constraints on the Collision Between the Chinese Altai and the West Junggar in Central Asia: Implication for Deformation Response and Geodynamic Evolution of Arc‐Arc Collision in 4D

AbstractArc‐arc collision represents one of crucial geological processes to shape mountain belts on the Earth. The deeply‐eroded Central Asian Orogenic Belt (CAOB) is characterized by the collision of multiple arc systems and provides a natural laboratory to understand arc‐arc collision in 4D given the exposure of crustal rocks at different levels. Here we focus on the ∼NW‐SE Irtysh fault zone, which represents a major suture zone within the CAOB to bound arc systems of the Chinese Altai and the West/East Junggar in NW China. Our structural work, for the first time, delineates the spatial position of the western segment of the Irtysh Fault between the Chinese Altai and the West Junggar, and demonstrates a phase of brittle strike‐slip deformation with sinistral kinematics in the Permian. An earlier episode of ∼NE‐SW shortening event affected both southern Chinese Altai and northern West Junggar, forming ∼NW‐SE fold structures. Both ∼NE‐SW shortening and sinistral strike‐slip faulting overlap in time with the collision of the Chinese Altai and the West Junggar during the latest Carboniferous to Permian as constrained by new detrital zircon data, thus indicating a transition from orthogonal collision to oblique convergence between the Chinese Altai and the West Junggar. A comparison with ductile deformation at deep structural levels along the eastern segment of the Irtysh Fault between the Chinese Altai and the East Junggar allows for investigation of arc‐arc collision in 4D, which highlights deformation decoupling across different crustal levels, with an intermediate episode of orogen‐parallel flow recorded within deep crustal rocks.

Variscan zircons everywhere? Multi-stage sedimentary recycling in Central Europe

Abstract The North German Basin is part of a Central European-wide sedimentary recycling system that has existed since at least the Neoproterozoic. Understanding the evolution of such a system is crucial for further studies, as the North German Basin inherits vast natural gas resources and may act as an intermediate sink for younger strata. This study presents new detrital zircon morphology, trace element and U–Pb age data obtained from Upper Rotliegend II strata (Upper Permian). Detrital zircon dating revealed Cambrian, Carboniferous and Permian main age clusters. There are also several minor Paleo-, Meso- and Neoproterozoic age clusters. Zircon grain morphologies show completely unrounded to completely rounded grains throughout each age range. The heterogeneity of the data is key to deciphering the sedimentary history of the Central German Basin, as the basin fill is most likely a mixture of (repeatedly) recycled material and also directly derived from bedrock sources. These results are supported by trace element data, which show a wide range of values indicating different magma sources. This study further explores the dispersal patterns of detrital zircon over time and demonstrates their complexity.

Late Triassic Tectonic Setting in Northeastern Margin of North China Craton: Insight into Sedimentary and Apatite Fission Tracks

The closure timing of the Paleo-Asian Ocean and the terminal stage of the Central Asian Orogenic Belt have been widely debated in the geological community. It’s known that the gradual scissor-like closure of the Paleo-Asian Ocean occurred from west to east during the Paleozoic period. However, it was not until the Triassic period that the complete closure of the ocean occurred at the northeastern margin of the North China Craton. Nevertheless, there is still much uncertainty regarding the Late Triassic tectonic setting in Northeast China. In this study, we focused on the Upper Triassic Dajianggang Formation, located in the Shuangyang area of central Jilin Province, which is situated on the northeastern margin of the North China Plate. Our aim was to determine the formation age of the Dajianggang Formation by analyzing the detrital particle composition, petrogeochemistry, detrital zircon U-Pb isotope dating, and apatite fission track thermochronology. Our results indicated that the primary sandstone provenance area of the Dajianggang Formation in the Shuangyang area is the island arc orogenic belt. The tectonic background of the sandstone provenance area is mainly a continental island arc environment. The provenance area is mostly composed of felsic rocks with sedimentary tendencies, and some of its material may have originated from the northern margin of the North China Craton or the eroded recycle orogenic belt. LA-ICP-MS U-Pb dating of detrital zircons shows that the Dajianggang Formation formed after 226.8 ± 5 Ma. Moreover, analysis of the thermal evolution history modelling shows that the Dajianggang Formation in the Shuangyang area continued to be deposited and heated in the early stage, and then experienced rapid exhumation around 30 Ma. This suggests that the study area underwent an orogenic process during the early stage of formation, but then transitioned into a post-orogenic extension period, which constrained the final closure of the Paleo-Asian Ocean prior to the Late Triassic period. In addition, our study indicates that the remote effect of the Pacific subduction did not reach the study area until 30 Ma. The central age of the detrital apatite fission track of sample 19DJ-1 is 94.2 ± 8.3 Ma, which is younger than its corresponding stratigraphic age. The two peak ages of the fission track analysis are 62.9 ± 5.4 Ma and 126 ± 11 Ma. These findings provide new evidence for the tectonic evolution of Northeast China and shed light on the Late Triassic tectonic setting, as well as the influence time of subsequent tectonic domains in the southern part of Northeast China.

Dataset of detrital zircon U–Pb ages and Hf isotopic compositions for the late Paleozoic–Mesozoic strata in the North China block

AbstractThe construction of databases of detrital zircon is important for Earth science research. A total of 27,915 U–Pb ages and 4,968 Hf isotopic compositions of detrital zircons from the upper Paleozoic–Mesozoic strata of the North China Block were compiled from articles in the Web of Science and the China National Knowledge Infrastructure. This dataset yields five age groups, at 3.9–1.0 Ga, 1,000–540 Ma, 540–360 Ma, 360–240 Ma and 240–95 Ma. The 3.9–1.0 Ga group has two peaks at ~2.5 and ~ 1.85 Ga. The 1,000–540 Ma and 540–380 Ma groups have three peaks at ~920 Ma, 780–750 Ma and ~ 440 Ma. Detrital zircon grains with ages of 360–240 Ma have multiple age peaks at ~380, ~320, ~280 and ~250 Ma. The group with ages of 240–95 Ma yields four peak ages at ~220, ~180, ~160 and ~120 Ma. Corresponding εHf(t) values range from −81.3 to +41.9, with two‐stage Hf model ages (TDM2) of 4,335–204 Ma. This dataset provides a comprehensive and systematic archive of detrital zircon data for Paleozoic–Mesozoic successions in the North China Block, which can be used to track tectono‐sedimentary and crustal evolution. In using this dataset, two issues need to be considered. First, the number of detrital zircon analyses from each sample varies markedly, which may influence the interpretation of the dataset. Second, there may be large uncertainties in the stratigraphic ages assigned to the samples.

Tectonic setting of Kaladgi-Badami basin and its possible connection with adjacent Proterozoic basins, Karnataka, India

Sedimentary rock types and basin geometries are interrelated with characteristic tectonic settings. In fact, sedimentation pattern at central stable cratonic areas are not same as that on continental margins. Kaladgi-Badami (KB) basinal feldspathic arenite (i.e., arkose) dominated rocks contain more plagioclase than potassium feldspar unlike the opposite scenario of Phanerozoic sandstones. Tectonic history of the KB basin has been interpreted since basin development, sedimentation through interrupting hiatus, tectonic reworking, redeposition at later developed depocenters and later exhumation, erosion, tectonism till Deccan volcanism and finally latest configuration. As per the International commission of Stratigraphy (ICS), principles of stratigraphic classification and usages of terminology of fundamental lithostratigraphic unit ‘Formation’ is reexamined in this paper. The definition of Formation as “smallest mappable rock unit with a definite lithologic characteristic that allow it to be distinguished from other such units” is improperly used because without mentioning a specific scale every unit is mappable or traceable. Therefore, the minimum mappable unit means the unit which can be at least visible in a scale in which entire basin can be seen. Based on this slight modification is proposed in the stratigraphy of KB basin. Geochronology based radiometric stratigraphy is best tool for determination of time sequence of geological events. However, it is always a matter of concern that dating methods and materials are often not suitable in sedimentary geology. In case of passive rifted sedimentary basins like Kaladgi, Badami and Bhima of the Dharwar Craton, there is negligible igneous events and indirect dating methods are mostly available. Detrital zircon dating can give maximum age or provenance age, which cannot be of much use. However, there are other indirect tools, which are already utilized by several workers earlier and based on the reviews and present observation and mapping compilation it is proposed that KB and Bhima basins used to be a single basin, and later tectonism followed by Deccan volcanism affected the present geographic continuity. Since the distance between westernmost Bhima basinal rocks and easternmost KB basinal rocks near Mudhebihal is nearly around 15km, it is logical to consider that these were geographically connected, because there is an intense faulting near to these basin margins.

Eocene to present evolution of the Pearl River, China: A quantitative provenance interpretation on large detrital zircon U–Pb geochronological data

AbstractDrainage evolution of the Pearl River, one of the major rivers in the eastern margin of the Asian continent, has important implications for the tectonomorphic evolution of the northern margin of the South China Sea and the southeastern Tibetan Plateau. Previous reconstructions using different methods suggested discrepant timings for the formation of river, ranging from Early Oligocene to Middle Miocene. Here, we address this heavily debated topic using quantitative unmixing modelling of detrital zircon data from the Pearl River Mouth Basin in the northern margin of the South China Sea. In this study, we develop a novel approach for estimating the relative contributions of detrital zircon sources to their shared sink, and propose to use the correlation coefficients among zircon contribution models to evaluate the trade‐off among sources with similar age spectra, to avoid the potential overinterpretation of individual contributions. Our new method is applied to new (997) and published detrital zircon U–Pb data from offshore boreholes and modern Pearl River samples to quantitatively interpret and reconstruct the sediment provenance of the Pearl River Mouth Basin and the development of the Pearl River. Our findings reveal that the provenance change of the Pearl River Mouth Basin can be divided into three main stages. Eocene sediments were mainly sourced in the intra‐basinal highlands and the eastern coastal tributaries, indicating a local drainage system. Early Oligocene provenances extended westward, as shown by the increase in sediment contribution from the central and western parts of the Pearl River (28% in total). Since the Late Oligocene, the eastern, central and western parts of the modern Pearl River have contributed equal amounts of zircons to the Pearl River Mouth Basin, indicating the establishment and long‐term stability of the modern‐like drainage system, as highlighted by our new data acquired from the borehole Miocene strata. The Late Oligocene westward expansion of the Pearl River is consistent with the timing of the coeval breakup and spreading of the South China Sea and the intensified Asian monsoon precipitation, highlighting the importance of base level fall and climate in controlling the drainage evolution.

Monazite and xenotime petrochronologic constraints on four Proterozoic tectonic episodes and ca. 1705 Ma age of the Uncompahgre Formation, southwestern Colorado, USA

Abstract The Proterozoic tectonic evolution of the southwestern USA remains incompletely understood due to limited constraints on the timing and conditions of the tectono-metamorphic phases and depositional age of metasedimentary successions. We integrated multi-scale compositional mapping, petrologic modeling, and in situ geochronology to constrain pressure-temperature-time paths from samples of Paleoproterozoic basement gneisses and overlying quartzites in southwestern Colorado, USA. Basement gneiss from the western Needle Mountains records metamorphic conditions of 600 °C at 0.75 GPa at 1764 ± 9 Ma and ~575 °C at 1741 ± 10 Ma. Gneiss sampled from drill core near Pagosa Springs, Colorado, records conditions of 700 °C at 1748 ± 9 Ma, 800 °C at 1.1 GPa at 1650 ± 40 Ma, 540 °C at 1570 ± 36 Ma, and 440 °C at 1424 ± 12 Ma. The Uncompahgre Formation was deposited at ca. 1705 Ma, as constrained by detrital monazite (1707 ± 8 Ma) and xenotime (1692 ± 40, 1725 ± 50 Ma), metamorphic xenotime (1650 ± 10 Ma), and published 40Ar/39Ar and detrital zircon data. Compositions of ca. 1705 Ma detrital monazite and xenotime are consistent with derivation from a garnet-bearing source in the Yavapai orogenic hinterland. The Vallecito Conglomerate and Uncompahgre Formation record macroscopic folding and greenschist-facies metamorphism at 1650 ± 10 Ma and temperatures of 270 °C to >570 °C at 1470–1400 Ma. Laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS) zircon geochronology yielded dates of 1775 ± 18 Ma from the Twilight Gneiss and 1696 ± 7 Ma from the Bakers Bridge Granite, supporting previous isotope dilution–thermal ionization mass spectrometry (ID-TIMS) dates. The Eolus Granite yielded a date of 1463 ± 6 Ma, which is older than previous 1.44–1.43 Ga ID-TIMS dates. The newly dated granite of Cataract Gulch is 1421 ± 12 Ma. In situ analysis of detrital and meta-morphic monazite and xenotime, igneous zircon, and quantitative thermobarometry, integrated with previously published constraints, indicate multiple tectonic episodes after the emplacement of 1800–1760 Ma arc-related rocks. The region experienced greenschist- to amphibolite-facies metamorphism (M1) from 1760 Ma to 1740 Ma, which was followed by the intrusion of granites at 1730–1695 Ma and deposition of the Uncompahgre Formation at ca. 1705 Ma, contemporaneous with the Yavapai orogeny. Metamorphism at 1680–1600 Ma was characterized by greenschist-facies conditions near Ouray, Colorado, and granulite-facies conditions near Pagosa Springs (M2) during the Mazatzal orogeny. From 1470 Ma to 1400 Ma, greenschist- to amphibolite-facies metamorphism (M3) and largely granitic plutonism occurred during the protracted Picuris orogeny. These results demonstrate the power of monazite and xenotime analyses to constrain depositional ages, provenance, and pressure-temperature-time (P-T-t) paths to resolve the compound orogenic history that is characteristic of most mountain belts.

Mid-Neoproterozoic tectonic switch from orogeny to intraplate extension in NW Tarim Craton: New evidence from a composite dike of the Aksu Group

It is widely acknowledged that the Tarim Craton plays a crucial role in the supercontinent Rodinia. However, the timing and regime of the Neoproterozoic orogeny, as well as the subsequent tectonic evolution along the northern margin of the Tarim Craton, remain contentious. Recent research has revealed a composite dike in the Aksu blueschist terrane located in the NW Tarim, which sheds new light on the pivotal Neoproterozoic tectonic transition. This dike comprises deformed granites and undeformed diabases, resulting from two-episode igneous events shortly after the orogenic metamorphism. The granites exhibit S-type affinities, with high silica, calcic-alkalic, and peraluminous compositions. Enriched isotopic signatures and diagnostic inherited zircons suggest that they derived from the metasedimentary rocks of the accretionary complex. Conversely, the following diabase dike displays tholeiitic affinity, right-sloping REE patterns, enriched LILEs, and a pronounced depletion of high-field-strength elements. Moderately enriched Sr-Nd isotopes and chondrite-akin Hf isotopes of these diabases imply that they were likely derived from partial melting of the metasomatized subcontinental lithospheric mantle. Zircon U-Pb chronological results reveal that the crystallization of these granites occurred at around 780 Ma. When combined with the maximum depositional age of protolith of the Aksu Group metapsammite obtained by detrital zircon dating, the metamorphic age of the Aksu blueschist terrane is limited to a short duration of 800–780 Ma, which is similar to the syn-orogenic metamorphism and crustal melting in the NE Tarim margin constrained to 830–790 Ma. Structural and petrological analysis suggests that the granites underwent deformation and dynamic recrystallization, while the diabases did not. This likely reflects the post-orogenic processes followed by the extrusion of mafic dike swarm associated with lithospheric stretching. The composite dike highlights a rapid tectonic shift from orogeny to intraplate extension during the mid-Neoproterozoic (780–760 Ma). Widespread late Neoproterozoic intraplate mafic and A-type granitic magmatism occurred in the Tarim and its adjacent blocks (Central Tianshan, Yili, and Kazakhstan) along the southwestern Central Asian Orogenic Belt, indicating that these blocks shared a similar geodynamic evolution related to the breakup of Rodinia.

The largest deflation basin in Asia reveals that the Miocene basin-filling sediments in the eastern Gobi Desert are an important dust source

Deflation is one of the most important exogenic forces in arid and semiarid regions. It not only shapes various wind erosion landforms but also releases a large amount of dust into the atmosphere. The Sunite Steppe in the eastern Gobi Desert is located in arid areas, where Neogene strata are widely distributed. However, the deflation process and its impact on landforms in this area are still unclear. We conducted comprehensive research on stratigraphy, sedimentology and geomorphology and found that there is a giant deflation basin (Sunite Deflation Basin) located to the west of the Otindag Sandy Land and to the east of the Tunggur Platform (Tamuqintala High Platform). With an area of over 8000 km2 and a volume of ∼393 km3, that deflation basin ranks second only to the Qattara Depression in North Africa and is much larger than Big Hollow in the United States; it is the second largest deflation basin in the world and the largest in Asia. Unlike the Qattara Depression (comma-like) and Big Hollow (rod-like), the Sunite Deflation Basin is shell-like in planform. The western edge of the basin is well defined with steep basin walls, indicating that the basin was developed on the ground represented by the Tunggur Platform. The basin bottom gradually becomes shallower from west to east, which is consistent with the prevailing westerly. Subordinate deflation basins, deflation mounds and blowouts are widely distributed in the Sunite Deflation Basin. The basement of the basin is mainly composed of Miocene alluvium and red clay, i.e., basin-filling sediments. The amount of dust (<20 μm) released from the basin that can be transported over long distances is preliminarily estimated to be as high as 216 km3. If all dust is deposited in the downwind loess area (∼37,200 km2) near Chifeng in Northeast China, the deposition thickness can reach ∼5.8 m. Nd isotope and U–Pb detrital zircon data suggest that the Miocene basin-filling sediments comprise aeolian deposits derived from the Gobi Desert and fluvial deposits derived from the Yinshan-Yanshan Orogenic Belt. The Sunite Deflation Basin must have begun forming after the deposition of basin-filling sediments (∼7.5 Ma) and most likely began to develop at ∼3.6 Ma as a result of the strengthened East Asian winter monsoon due to global cooling.

Southwest Borneo, an autochthonous Pangea-Eurasia assembly proxy: Insights from detrital zircon record

Abstract The current tectonic model for Borneo in SE Asia suggests that the SW Borneo block rifted from NW Australia at ca. 190 Ma and drifted across the Tethyan Ocean to collide with Eurasia in the Early Cretaceous. But, the global zircon Hf trend after 200 Ma indicates that circum-Pacific-style accretionary orogens prevail. The SW Borneo detrital zircon data set, which combines our new data with previous data, shows consistent age peaks (ca. 250 Ma, 1.9–1.8 Ga, and 2.5–2.4 Ga) in late Permian to Early Cretaceous samples. The Banda terranes, a notable block derived from NW Australia, have distinct detrital zircon age peaks for pre-breakup and post-breakup. Available Borneo detrital zircon εHf(t) values for ca. 1.8 Ga and 2.4 Ga are indistinguishable from those of NW Australia sources, but εHf(t) values for 300–200 Ma are more negative than those from the Gondwanide orogen and are more similar to those from the Peninsular Malaysia Indosinian orogen. We suggest SW Borneo is a Triassic accretion zone at eastern Cimmeria that rifted from NW Australia in the Permian. The ca. 250 Ma negative εHf(t) values present in samples are characteristic of Tethyan-style collisional orogens and show participation in Pangea assembly. SW Borneo underwent further autochthonous accretion along its SE margin (ca. 186 Ma and ca. 140 Ma) in a Jurassic Meso-Tethys and Paleo-Pacific supra–subduction zone setting. Our revision locates SW Borneo with other SE Tethysides blocks in Eurasia where accretionary orogens have influenced rises after 200 Ma.

Yangtze and Cathaysia blocks of South China: Their separate positions in Gondwana until early Paleozoic juxtaposition

The position of South China in Gondwana remains controversial. In all previous models, the Yangtze and Cathaysia blocks, the two major components of South China, were amalgamated by the Tonian, and South China was considered to be a single coherent block in Gondwana. Based on a summary and critical reevaluation of available paleomagnetic, paleontological, stratigraphic, and detrital zircon data, we propose that the Yangtze and Cathaysia blocks were not juxtaposed until the early Paleozoic and were located at two separate parts of the northern margin of Gondwana before that time. The Yangtze block was located to the northwest of India in the Ediacaran and early Cambrian. Cathaysia was close to or a part of northern Australia in the Ediacaran, when Australia and India were separated by the Kuunga Ocean, and amalgamated with the eastern margin of India in the late Ediacaran to early Cambrian when the ocean closed. Our model implies that the early Paleozoic orogenesis in South China could have been related to two distinct events, the late Ediacaran to early Cambrian collision of Cathaysia/Australia with India (the Kuunga orogeny) and the Late Ordovician amalgamation of Cathaysia with Yangtze. It also implies that the Yangtze and Cathaysia blocks likely occupied two separate positions in Rodinia.

New insights into the Cretaceous evolution of the Western Amazonian paleodrainage system

The geological history of the Amazon River is a complex story driven by geodynamic processes operating in the South American plate. In spite of recent research, the pre-Neogene structure of Amazon paleodrainage is still underconstrained. A recent study has suggested that the western Amazonian paleodrainage system was reversed, cratonic in origin during the Cretaceous. However, the extent and duration of this system are not well-constrained. To add new constraints, we investigated the sources of Cretaceous sedimentary rocks in the Brazilian Acre and Peruvian Madre de Dios basins, based on major and trace element concentrations, Sm–Nd isotopic compositions, and U–Pb detrital zircon dating. The late Cretaceous samples of the Acre Basin have εNd(0) values between −21.2 and −8.4 and zircon grains derived from terranes situated in the easternmost part of the Amazonian Craton: Ventuari–Tapajos (2.0–1.82 Ga) and Rio Negro–Juruena (1.82–1.54 Ga). In contrast, the Madre de Dios Basin samples have εNd(0) values ranging from −15.2 to −7.1 and a wide range of U–Pb zircon age distributions. The samples from the northern part of the basin (MD234 and MD238) are dominated by zircon ages between 0.9 and 1.3 Ga (Grenville/Sunsás, 30 %–43 %) and 0.5 and 0.7 Ga (Brazilian/Pampean, 26 %–16 %) with felsic provenance. The oldest MD234 sample also shows a dominant contribution from Paleozoic zircon (20 %). On the other hand, the samples from the southern part of the Madre de Dios Basin (samples MD-2019-4A; MD-2019-10; MD-2019-13; MD-2019-11D and MD-2019-12A) have U–Pb age distributions dominated by zircon ages between 0.9 and 1.3 Ga (Grenville/Sunsás, 30 %–45 %) and 1.54 and 1.3 Ga (Rondonia–San Ignácio, 16 %–43 %), pointing to a cratonic origin for these sedimentary rocks. To elucidate the distinction in provenance between the samples from the northern and southern parts of the Madre de Dios Basin, we suggest that a structural barrier (the Madidi Arch (?)) was active during the late Cretaceous. In this scenario, the northern part of the Madre de Dios Basin had similar sedimentary sources as the nearby basins like Huallaga, Bagua, Ucayali, and Marañón, whereas, in the southern part of the basin, sedimentation was influenced by local sources. Together with previously published studies, these data indicate that the continent-wide cratonic drainage developed between the Cenomanian and Maastrichtian in response to the Purus Arch uplift was probably driven by a geodynamic process related to the post-rift opening of the Atlantic Equatorial Ocean.

Karst-bauxite formation during the Great Oxidation Event indicated by dating of authigenic rutile and its thorium content

Aluminium (Al)-rich palaeosols—i.e., palaeobauxite deposits—should have formed in karst depressions in carbonate sequences as a result of acidic solutions from oxidative weathering of sulfide minerals during the Great Oxidation Event (GOE), but no GOE-related karst-palaeobauxite deposits have so far been recorded. Here, we report results of in situ uranium–lead (U–Pb) dating of detrital zircon and spatially associated rutile from a metamorphosed Al-rich rock within a dolomite sequence in the Quadrilátero Ferrífero (QF) of Minas Gerais, Brazil, known as the Gandarela Formation. Rutile grains are highly enriched in thorium (Th = 3–46 ppm; Th/U ratio = 0.3–3.7) and yielded an isochron, lower-intercept age of ca. 2.12 Ga, which coincides with the final phase of the GOE—i.e., the Lomagundi event. The rutile age represents either authigenic growth of TiO2 enriched in Th, U and Pb during bauxite formation, or subsequent rutile crystallisation during metamorphic overprint. Both cases require an authigenic origin for the rutile. Its high Th contents can be used as a palaeoenvironmental indicator for decreased soil pH during the GOE. Our results also have implications for iron (Fe)-ore genesis in the QF. This study demonstrates that in situ U–Th–Pb-isotope analyses of rutile can place tight constraints on the age and nature of palaeosols.

Orogens and detritus: unravelling the Mesoproterozoic tectonic geography of northern Australia through coupled detrital thermo- and geo-chronometers

This study presents detrital muscovite 40Ar/39Ar data from the Mesoproterozoic Roper Group and overlying informally named successions, in the Beetaloo Sub-basin, northern Australia. Detrital muscovite chronology reveals tectono-thermal processes within source regions and provides new constraints on the basin provenance, revising previous interpretations based on detrital zircon data. Detrital thermo- and geochronology, together demonstrate three main periods when the basin paleogeography was altered that correspond to the evolving tectonic history of the North Australia Craton (NAC) through the Mesoproterozoic. The first is characterised by an increased sediment contribution from source regions that lay along the eastern margin of Proterozoic Australia. These source regions are interpreted to have formed the uplifted rift-shoulders between Proterozoic Australia and Laurentia at ca 1.45 Ga. After that, sediments derived from eastern Proterozoic Australia sources become less voluminous up-section. The youngest analysed formation from the Roper Group, the Kyalla Formation, was predominately from sources to the south of the basin, representing another modification of basin geography. This is interpreted to result from the closure/subduction of the Mirning Ocean as the West Australian Craton (WAC) approached and collided with the NAC, resulting in an uplift of the southern margin of the NAC, at ca 1.35–1.31 Ga. The uppermost Mesoproterozoic to lower Neoproterozoic sandstone successions that overlie the Roper Group were derived from the Musgrave Province. Coupled detrital zircon and muscovite data imply a rapid cooling at ca 1.20–1.15 Ga that is interpreted to reflect syn-orogenic exhumation during the Musgrave Orogeny. Furthermore, data from the Beetaloo Sub-basin suggest that the changed basin tectonic settings reshaped basin geography and result in distinctive detrital zircon and muscovite geochronology records. In this study, we used the detrital U–Pb zircon and muscovite 40Ar/39Ar age data from the Beetaloo Sub-basin and a range of other basins deposited in different tectonic environments, including the convergent, collisional and extensional settings, to reconstruct the basin tectonic geography and illustrate various tectonic controls on basin formation in different tectonic backgrounds. KEY POINTS Detrital muscovite 40Ar/39Ar data provide thermochronological constraints on basin provenance, complementing previous interpretations based on detrital zircon data. Spatial and temporal variation of provenance reconstructs the basin tectonic geography, reflecting the Mesoproterozoic tectonic history of the North Australia Craton. Coupled thermo- and geochronology constrain tectonic settings of basin deposition.