Detrital Zircon Age Spectra Research Articles

Reconstructing the Lancang Terrane (SW Yunnan) and implications for early Paleozoic Proto-Tethys evolution at the northern margin of Gondwana

The Lancang Group in SW Yunnan constitutes a pivotal component of the continental margin bounding the Proto- and Paleo-Tethys oceans, yet its formation timing, composition and tectonic affinity remain ill-defined. In this contribution, we present new zircon U-Pb age and whole-rock geochemistry data from volcanic and sedimentary rock units, which are compiled with published data, to refine the depositional age, provenance and nature of the group and its host terrane. The Lancang Group consists of five formations, two of which (Manlai and Huimin) contain abundant metavolcanic rocks. The metavolcanic rocks show a secular change in geochemistry, from EMORB-like calc-alkaline series of the ca. 495 Ma Manlai Formation, to arc-like high-K series of the Huimin Formation. Five metavolcanic samples from the Huimin Formation yielded zircon U-Pb ages between 478 ± 5 Ma and 442 ± 5 Ma. The late Cambrian-Ordovician arc magmatism is related to an active continental margin setting associated with subduction of the Proto-Tethys Ocean. The time-integrated geochemical variation shown by the volcanic rocks likely reflects evolving maturity of the arc system. The youngest detrital zircon ages of the five formations, in conjunction with age constraints from the interbedded volcanic rocks, suggest that the Lancang Group was largely accumulated during the early Paleozoic. The Lancang Terrane is reconstructed as a continental block, which formed part of the magmatically-active margin of the Proto-Tethys during the early Paleozoic. Provenance analysis based on detrital zircon age spectra and Hf isotope data indicates Gondwana affinities of the terrane. Furthermore, xenocrystic zircon ages and zircon Hf and whole-rock Nd model ages from igneous rocks support presence of Neoarchean-Mesoproterozoic basement underlying the terrane. The reconstructed Lancang Terrane bears important implications for understanding the configuration of the northern margin of Eastern Gondwana and the relationship between the Proto- and Paleo-Tethys oceans.

Cretaceous forearc basin remnant sediments in the eastern Yarlung Zangbo suture zone, near the eastern Himalaya syntaxis

Low-grade metamorphosed Cretaceous sedimentary records of forearc basin systems in the eastern part of the Transhimalaya (Gangdese) arc system have not been reported yet, impairing understanding of the Mesozoic-Cenozoic convergent margin processes along the southern margin of Asia. This study incorporates observations from petrography, stratigraphy, sedimentology, and analyses of detrital-zircon geochronology and bulk-rock Sr-Nd isotope for a series of low-grade metamorphosed sedimentary rocks referred to as the Lilong succession in the eastern Yarlung Zangbo suture zone, east of Langxian, in southeastern Tibet, China. Field observations reveal that this unit has three different lithological associations (I, II, and III) including gravel-coarse sandy inner-middle submarine fan facies, sandy-muddy middle-outer submarine fan facies, and silty-muddy outer submarine fan and/or deep sea plain facies moving higher in the succession. Detrital-zircon geochronology indicates a maximum depositional age of ~110 Ma and the absence of younger zircons that are dominant in the Gangdese batholith north of the basin suggests the minimum depositional age ~ 85 Ma, comprising an interval of the Albian-Santonian age. Volcanic and granitic clasts in sandstones/conglomerates, εNd(0) values (−0.09 and 4.6) and 87Sr/86Sr ratios (0.704105–0.704770) of slates, and detrital zircon age spectra (mainly 100–140 Ma) demonstrate provenance from the central-northern and southern Lhasa Terrane. In addition, there is evidence for recycling of cherty beds of the Chongdui Formation. Similarities between provenance, lithofacies, and tectonic setting lead us to interpret that the newly identified remnant unit correlates to the Ngamring Formation in the Xigaze forearc basin. When taking into account the lower Bomi Group and Nyingchi complex, we propose that the Lilong succession and the metamorphosed composite in the eastern Himalayan syntaxis are counterpart remnants of the eastern Xigaze forearc basin system, which are different from the two forearc basin systems in the western Himalaya.

Provenance and tectonic setting of the Triassic clastic deposits in the Napo basin, South China: evidence from petrography, whole-rock geochemistry and detrital zircon U–Pb geochronology

AbstractThe provenance and tectonic setting of the Lower–Middle Triassic clastic sediments from the Napo basin, South China, have been examined here using detrital modes, whole-rock geochemistry and detrital zircon U–Pb ages. Field investigations indicate that these sediments consist of fan delta, slope and turbidity fan facies with dominantly southward palaeocurrent directions. Detrital modes and geochemical characteristics of the clastic rocks indicate that they were derived from mixed magmatic arc and Palaeozoic successions in a continental island arc setting, with no significant sediment recycling. The U–Pb age spectra of sandstone detrital zircons from different stratigraphic positions are similar, with one major group (300–230 Ma), two subordinate groups (400–320 Ma and 480–420 Ma, respectively) and two scattered groups (1200–800 Ma and 2000–1700 Ma, respectively). Thus, we consider that the north late Permian – Middle Triassic volcanic rocks and the uplifted Palaeozoic sedimentary/volcanic sequences constituted the predominant sources. The detritus derived from the late Permian Emeishan mafic rocks is subordinate and limited. The pre-Devonian zircons are likely sedimentary-recycled or magmatic-captured instead of directly derived from the early Palaeozoic orogen (e.g. Yunkai massif) and Neoproterozoic Jiangnan orogen because of the topographic barrier of a magmatic arc and carbonate platform. Considering the spatial and temporal distribution characteristics of the volcanic arc and ophiolite, we suggest that the Triassic Napo basin was a fore-arc basin within a continental island arc setting, which developed in response to the northward subduction of the Babu–Cao Bang branch ocean beneath the South China Block.

Decoupling of the detrital linkage between proximal dunefields and early and middle Pleistocene accumulation in the Chinese Loess Plateau: evidence from the Badain Jaran and Tengger sandy deserts

The dunefields upwind of the Chinese Loess Plateau (CLP) are widely regarded as the major source of the sediments of the CLP. To test this inference, we conducted a source tracing study using U–Pb age spectra of detrital zircons from the central Badain Jaran Desert (BJD). The results reveal that since 1.1 Ma the sediments in the central BJD have originated predominantly from the Gobi-Altay Mountains (GAMs), with a dominant Northern Tibetan Plateau (NTP) provenance at ∼0.7 Ma and at the present. Together with a previous study of the neighboring Tengger Desert (TD), our results support the conclusion that during 2.35–0.62 Ma the central parts of the proximal dunefields of the BJD and TD acted as reservoirs of sediments deflated mainly from strata with a GAMs-origin, with the addition of NTP-derived sediments after 0.36 Ma. Comparison of the original provenance areas of sediments in the central parts of the BJD and TD with the loess deposits in the central and southern CLP indicates that the proximal dunefields of the BJD and TD were not the dominant sources of dust transported to the CLP during early to middle Quaternary. Based on our results, combined with evidence from previous studies, we propose that NTP-derived sediments dominated accumulation in the CLP for most of the Quaternary, while during 2.35–0.62 Ma the proximal dunefields, including the BJD and TD, acted only as reservoirs of sediments deflated and eroded predominantly from the GAMs. Essentially, these sandy deserts functioned as transfer stations, which, after ∼0.36 Ma, received increased amounts of NTP-derived sediments and subsequently supplied silt to downwind areas, including the CLP.

Provenance evolution during passive- to active-margin transition unraveled from an accretionary complex from the Bangong-Nujiang suture zone: Insights into Early Mesozoic Meso-Tethys subduction and source-area tectonics

The South Qiangtang terrane (SQT), the Tibetan representative of the Cimmerian continent, is bounded in the south by the Bangong-Nujiang suture zone (BNSZ). The BNSZ is geologically manifested by the Mugagangri Group (MG) accretionary complexes developed during northward Meso-Tethyan subduction, whose timing and processes are, however, contentious. Herein, we conducted provenance analysis on the MG trench deposits, via petrography, whole-rock geochemistry and detrital-zircon geochronology. The results reveal a complete picture of provenance evolution during passive- to active-margin transition (from subduction initiation through fringing oceanic-arc, to continental-arc developments) at the SQT margin. In particular, the earliest trench deposits (subunit Trma; ~222 Ma), which contain olistostromes with blocks of oolitic limestone shed from the destructing SQT passive margin, mark the subduction initiation. A second subunit (Trmb; ~210 Ma) has periodically elevated volcanogenic components. Conglomerates of subunit Trmb have abundant basaltic clasts of intra-oceanic arc geochemical affinities, which were likely derived from an intra-oceanic arc fringing the SQT. The youngest subunit (Jmd; ~190 Ma) exhibits enriched ferromagnesian elements and a major youngest detrital-zircon age peak, indicating a continental-arc provenance. Moreover, detrital-zircon age spectra suggest that, at ~210 Ma, the central Qiangtang metamorphic belt became an important source area, and the North Qiangtang terrane (NQT) replaced SQT as the main provenance. This is best explained by that the SQT underthrusted beneath the NQT and was downwarped to form a foreland basin. Our findings confirm that the initial subduction of Meso-Tethys beneath SQT was coeval to other Cimmerian terranes, likely a uniform response to the Paleo-Tethys closure and collision between Eurasia (NQT) and Cimmeria (SQT).

Provenance transition from the North China Craton to the Grenvillian orogeny-related source: Evidence from late Mesoproterozoic-early Neoproterozoic strata in the Liao-Ji area

Late Paleoproterozoic to early Neoproterozoic strata in Liao-Ji area (eastern Liaoning-southern Jilin) on the eastern margin of the North China Craton (NCC) provide a significant record of sediment provenance transition from the NCC to the Grenvillian orogeny. A >3000-m-thick sequence of fluvial, margin marine, and offshore marine sediments were preserved, including the Madaling, Baifangzi, Yongning, Diaoyutai, Nanfen and Qiaotou formations. To evaluate the relationship of Rodinia sediment delivery to this area, we synthesize 3177 geochronology data from the Liao-Ji area of which 1499 detrital zircon and 319 monazite ages from 17 sample analyses are newly reported herein. The results indicate that the Madaling, Baifangzi, Yongning, Diaoyutai (not including Dalian samples) and Nanfen Formations have two major peaks at 1.8 Ga and 2.5 Ga. The depositional ages of the formations are 1.27–0.92 Ga, as constrained by the ages of the youngest detrital zircons and later mafic intrusions. In the Madaling/Baifangzi/Yongning period, Longgang and Liaonan blocks and the late Paleoproterozoic Jiao-Liao-Ji belt were dominant in deposition. During the Diaoyutai-Nanfen period, grains derived from Mesoproterozoic rocks began to accumulate in topographically low areas, such as the Fuzhou Gulf. In the Qiaotou period, Mesoproterozoic grain-derived sources dominated the deposition. Combining the studies of late Mesoproteorozoic-early Neoperoterozoic successions from the Xuhuai and Jiaobei areas, the detrital zircon spectra in the Liao-Ji area document the transition from the initial NCC to a distant Grenvillian orogeny related provenance (Laurentia, Siberia, SF-Congo and Baltica have been excluded) from possible south/southeast.

A missing piece between Laurentia and the North China Craton in Rodinia: Evidence from metasedimentary rocks of the North Qinling Terrane in central China

The North Qinling Terrane was a microcontinent in the Late Neoproterozoic and then subducted northwards beneath the North China Craton for regional metamorphism in the Early Paleozoic. In order to constrain its location in supercontinent Rodinia, metasedimentary rocks were sampled from it for a combined study of whole-rock major and trace elements as well as zircon U-Pb ages and Lu-Hf isotopes. The metasedimentary rocks show greywacke compositions with A/CNK ratios of 0.99–1.28 and upper continental crust-like trace element patterns. They have metamorphic ages of ca. 510–490 Ma, recording continental collision for the regional metamorphism. The youngest detrital zircon U-Pb ages from three metasedimentary rocks are 1161 ± 54 Ma, 954 ± 15 Ma, 861 ± 10 Ma, respectively. In combination with ages of granitic intrusions of 960 to 890 Ma in the target region, their deposition ages are constrained to be 1110–960 Ma, ca. 960 Ma and ca. 860 Ma, respectively. The cumulative proportions of the difference between the detrital zircon crystallization ages and the deposition ages for the sediments of ca. 960 Ma and ca. 860 Ma suggest their deposition in a collisional setting. Detrital zircon age spectrum from the Qinling Group yields two major populations at 1000–900 Ma and 1700–1400 Ma and three subordinate populations at 900–800 Ma, 1300–1200 Ma and 1800–1700 Ma with rare Neoarchean grains. Neoproterozoic detrital zircons mainly have negative εHf(t) values, consistent with Neoproterozoic granitoids in the North Qinling Terrane. On the other hand, Mesoproterozoic detrital zircons mainly have positive εHf(t) values, similar to those in East Laurentia and East Greenland. This means that the major provenance of sediments in the Qinling Group was the North Qinling Terrane itself and East Laurentia, supporting the connection between the North Qinling Terrane and East Laurentia in Rodinia prior to its breakup. In combination with the coeval strata in the southern margin of the North China Craton, we propose that the North Qinling Terrane is a missing piece connecting the southern margin of the North China Craton with the northern part of East Laurentia in Rodinia in the early Neoproterozoic.

Transcurrent displacement of the Cadomian magmatic arc

The Ossa-Morena Zone in Iberia, and equivalent terranes in northern France and Central Europe, are thought to be paleogeographically linked to the West African Craton at Ediacaran to early Paleozoic times. Evidence is mainly based on metasedimentary rock detrital zircon age spectra, characterized by two dominant populations of Paleoproterozoic and Cryogenian-Ediacaran ages, with a systematic lack of late Stenian – early Tonian zircon grains. We report here U-Pb-Hf results on detrital zircon grains from six Ordovician-Devonian metasedimentary rocks from the Ossa-Morena Zone. In addition to the Cryogenian-Ediacaran and Paleoproterozoic populations already recognized in previous studies on uppermost Ediacaran and lower Cambrian rocks, the samples ubiquitously show a late Stenian – early Tonian population centered at ≈1 Ga and representing ≈20% of the concordant dates. The εHf versus age plot of the studied samples mainly depicts two vertical arrays corresponding to the Cryogenian-Ediacaran and Stenian-Tonian detrital zircon populations, which spread from εHf values of ≈10 down to ≈−20. The detrital zircon age distribution and Hf isotope signature of the studied rocks point to the Sahara metacraton as the most plausible sediment source. The eastward translation of the continental ribbon represented by the Ossa-Morena Zone and equivalent domains of the Variscides from an original position close to the West African Craton to an Ordovician-Devonian location close to the Sahara metacraton probably occurred at latest Ediacaran – earliest Cambrian times in a dextral strike-slip tectonic setting that post-dated Pan-African collision and Cadomian subduction.

The birth of the Alps: Ediacaran to Paleozoic accretionary processes and crustal growth along the northern Gondwana margin

New whole-rock geochemical and coupled U–Pb and Lu–Hf LA-ICP-MS zircon data of metasedimentary rocks of the Austroalpine, South Alpine and Penninic basement domains are presented, to disentangle the pre-Variscan tectonic evolution of the proto-Alps. The studied units seem to record distinct stages of protracted Late Ediacaran to Carboniferous tectonosedimentary processes prior to the Variscan collision. In the case of Austroalpine and South Alpine units, nevertheless, no major differences in terms of provenance are observed, since most detrital zircon samples are characterized by a major Pan-African peak. Their detrital zircon spectra record a provenance from the northeastern Saharan Metacraton and the Sinai basement at the northern Arabian-Nubian Shield, being thus located along the eastern Early Paleozoic northern Gondwana margin, whereas sources located further west are inferred for the Penninic Unit, which might have been placed close to the Moldanubian Unit of the Bohemian Massif. In any case, it is thus clear that the Alpine basement remained in a close position to the Gondwana mainland at least during the Early Paleozoic. The Late Ediacaran to Silurian tectonic evolution, which includes Cadomian and Cenerian tectonometamorphic and magmatic processes, seem thus to record a continuum related to a retreating-mode accretionary orogen, with diachronous back-arc basin opening and possibly discrete compressional/transpressional pulses linked to changes in subduction zone dynamics. On the other hand, it is inferred that the Alpine basement essentially comprises Pan-African metasedimentary and subordinate metaigneous rocks, possibly with very few Early Neoproterozoic relics. This basement was significantly reworked during the protracted Paleozoic orogenic evolution, due to anatexis and/or assimilation by mantle-derived juvenile magmatism.

Late Neoproterozoic to early Paleozoic paleogeographic position of the Yangtze block and the change of tectonic setting in its northwestern margin: Evidence from detrital zircon U-Pb ages and Hf isotopes of sedimentary rocks

AbstractThe crustal evolution of the Yangtze block and its tectonic affinity to other continents of Rodinia and subsequent Gondwana have not been well constrained. Here, we present new U-Pb ages and Hf isotopes of detrital zircons from the late Neoproterozoic to early Paleozoic sedimentary rocks in the northwestern margin of the Yangtze block to provide critical constraints on their provenance and tectonic settings. The detrital zircons of two late Neoproterozoic samples have a small range of ages (0.87–0.67 Ga) with a dominant age peak at 0.73 Ga, which were likely derived from the Hannan-Micangshan arc in the northwestern margin of the Yangtze block. In addition, the cumulative distribution curves from the difference between the depositional age and the crystalline age (CA–DA) together with the mostly positive εHf(t) values of these zircon crystals (−6.8 to +10.7, ~90% zircon grains with εHf[t] > 0) suggest these samples were deposited in a convergent setting during the late Neoproterozoic. In contrast, the Cambrian–Silurian sediments share a similar detrital zircon age spectrum that is dominated by Grenvillian ages (1.11–0.72 Ga), with minor late Paleoproterozoic (ca. 2.31–1.71 Ga), Mesoarchean to Neoarchean (3.16–2.69 Ga), and latest Archean to early Paleoproterozoic (2.57–2.38 Ga) populations, suggesting a significant change in the sedimentary provenance and tectonic setting from a convergent setting after the breakup of Rodinia to an extensional setting during the assembly of Gondwana. However, the presence of abundant Grenvillian and Neoarchean ages, along with their moderately to highly rounded shapes, indicates a possible sedimentary provenance from exotic continental terrane(s). Considering the potential source areas around the Yangtze block when it was a part of Rodinia or Gondwana, we suggest that the source of these early Paleozoic sediments had typical Gondwana affinities, such as the Himalaya, north India, and Tarim, which is also supported by their stratigraphic similarity, newly published paleomagnetic data, and tectono-thermal events in the northern fragments of Gondwana. This implies that after prolonged subduction in the Neoproterozoic, the northwestern margin of the Yangtze block began to be incorporated into the assembly of Gondwana and then accept sediments from the northern margin of Gondwanaland in a passive continental margin setting.

Insights into evolution of a rift basin: Provenance of the middle Eocene-lower Oligocene strata of the Beibuwan Basin, South China Sea from detrital zircon

Investigating rift basins and their provenance is difficult because their tectonic framework is continuously evolving. The Beibuwan Basin in the South China Sea is a typical rift basin that shares many characteristics of major rift basins worldwide. We present new detrital zircon UPb ages from the Beibuwan basin and, by combining with published data from surrounding drainages, are able to define its potential sources and to investigate its provenance evolution from the middle Eocene-lower Oligocene. Detrital zircon age spectra from distinct structural units and formations of the rift basin reveal spatial-temporal differences in provenance. In the middle-upper Eocene, a similar age pattern with major peaks at 263–253 Ma and 450–416 Ma is preserved across the basin and suggests that sediment was uniformly derived from the Yunkai Massif and Hainan Island. In contrast, during the lower Oligocene the basin displays markedly diverse ages with peaks at 250–243, 416, 756, 967–945, 1096–1084 Ma. The increase of Neoproterozoic zircons in the lower Oligocene stratum suggests that a major change in provenance occurred, most likely associated with the reorganization of the paleo-Pearl River along its central reaches due to a topography reversal associated with the uplift of Tibet and the onset of seafloor spreading in the South China Sea. Our spatial analysis of ages indicates that during the lower Oligocene, the detrital input varied across the basin. Rifting processes in the Beibuwan Basin generated multiple isolated depocenters separated by intra-basinal highs. The basin's architecture greatly affected sediment routing, with structural highs serving as barriers to sediment transport. Sediment provenance in the Beibuwan Basin is primarily controlled by drainage evolution and isolated depocenters associated with an evolving topography, processes which are relevant to the evolution of rift basins globally.

Constraints on the age and geodynamic setting of the iron formations and anhydrite Fe-(Ba) deposits in the Bulunkuole Group of the Taxkorgan area, NW China

• Bulunkuole Group (BG) and associated mineral deposits is both early Cambrian in age. • Volcanic-sedimentary rocks in the BG reveal a back-arc basin depositional setting. • Iron formations deposited in newborn back-arc basin from redox-stratified water column. • Anhydrite Fe-(Ba) deposits formed in restricted sulfate-rich water during back-arc basin collapse. Here we present detailed field observations, zircon U-Pb-Hf isotopes, whole-rock geochemical, and Sm-Nd isotopic data for the volcanic-sedimentary rocks within the Bulunkuole Group (BG) in the Taxkorgan area, northwestern China in order to reveal significant information on the formation age and tectonic setting of the iron formations (IFs) and anhydrite Fe-(Ba) deposits hosted by this group. Exposed rocks in the BG are broadly grouped into three subgroups: the lowermost Subgroup 1 is a bimodal volcanic suit (basalts and dacites) interbedded with IF layers; the overlying Subgroup 2 is a clastic sedimentary sequence hosting abundant anhydrite Fe-(Ba) mineralization; and the uppermost Subgroup 3 is dominated by carbonate rocks. Zircon U-Pb ages provide constraints on the formation age of the BG. Specifically, the bimodal volcanism occurred at ~ 540–521 Ma and the sedimentary rocks deposited after 540 Ma. Basalts from the BG bimodal suit are characterized by slightly enriched LREE patterns and pronounced to insignificant negative Nb anomalies when normalized to primitive mantle compositions. These features are comparable with those of modern N-MORB and back-arc basin basalts. Combined with highly heterogeneous Nd isotopes ( ε Nd (t) = 0.2–4.4), these suggest that their magmatic precursors were derived from partial melting of a depleted mantle modified by slab-derived fluids, and interacted with minor crustal components during ascending. By comparison, the BG dacites display gently sloped to flat LREE patterns with a FII-type felsic affinity and a range of negative to positive ε Nd (t) values (-5.8~+0.7). They are inferred to be generated by partial melting of the old continental crust at relatively shallow levels with variable addition of juvenile material. The BG clastic sediments were dominated by greywacke and arkose. Their diagnostic geochemical features, detrital zircon age spectra, and in situ zircon Hf isotopic data indicate that they were mainly derived from weathering of the early Cambrian felsic rocks. Together, these characteristics above, integrated with previous studies, suggest that the BG and related IFs and anhydrite Fe-(Ba) deposits were formed on an active continental margin (possibly back-arc basin) during the southward subduction of the Proto-Tethys Ocean beneath the Taxkorgan-Tianshuihai Terrane.

Jurassic dinosaurs on the move: Gastrolith provenance and long‐distance migration

AbstractHere, we present the detrital zircon age spectra for five (n = 36, 68, 66, 41, 29) red quartzite gastroliths collected from the top of the Upper Jurassic Morrison Formation in the eastern Bighorn Basin, Wyoming, USA. The detrital zircon age spectra reveal geon 17 maximum depositional ages, and age peaks that are Yavapai (geon 17), Penokean (geon 18) and Archean (>geon 25). The colour, texture, composition and zircon age spectra of these exoliths are indistinguishable from those of geon 16 (i.e. Baraboo interval) quartzites present in the Laurentian midcontinent more than 1,000 km to the east. We interpret that these gastroliths were ingested by dinosaurs, most likely sauropods, in the Laurentian midcontinent and then transported in their digestive tracts to the site of deposition. These data support the hypothesis of long‐distance dinosaur migration, perhaps following low energy, continental‐scale drainage systems that flowed from the Appalachian highlands to the Morrison Formation depositional basin.

Detrital zircon and rutile U–Pb, Hf isotopes and heavy mineral assemblages of Israeli Miocene sands: Fingerprinting the Arabian provenance of the Levant

AbstractIsolated, Miocene continental basins scattered over Israel and Jordan represent the remnants of a continental‐wide fluvial system, which originated in Arabia and transported siliciclastic sediments westward to the deep Levant Basin. These basins define two geographically separated sedimentary provinces. The detrital zircon age spectra in both provinces are dominated by Neoproterozoic U‐Pb ages (550–1,000 Ma), resembling those of Paleozoic‐Mesozoic sandstones exposed along the uplifted Red Sea Rift flank. However, while the southern province exhibits two prominent peaks at ~600 and ~1,000 Ma, similar to those seen in Cambrian‐Ordovician sandstones in southern Israel and Jordan, the northern province shows an additional significant age peak at ~800 Ma and its overall spectrum resembles that of Devonian sandstones in northern Saudi Arabia. These variations distinguish the two Miocene clastic outliers as pertaining to two separate, NW‐directed transport systems delivering siliciclastic sediments from Arabia towards the deep Levant Basin. The detrital zircon U‐Pb‐Hf signal of the Israeli Miocene clastic units differs from that of the River Nile, particularly in the lack of Cenozoic‐Mesozoic‐aged zircons in the former. This allows us to distinguish the properties of the fluvial system that existed in Arabia, on the eastern side of the Red Sea, from that of the River Nile that drained its western flanks. While it is commonly accepted that the (proto‐)Nile River played a key role in the Levant Basin fill, the eastern fluvial system that prevailed on the Arabian side may have been also important.

Provenance of Precambrian basement of the Brunovistulian Terrane: New data from its Silesian part (Czech Republic, Poland), central Europe, and implications for Gondwana break-up

Brunovistulia is a complex superterrane in central Europe, the western part of which became tectonically involved in the Variscan belt and formed its Precambrian basement. The Silesian part of the Brunovistulian Terrane embraces metasediments and metavolcanic rocks whose protolith ages, provenance, geotectonic setting and pre-Variscan palaeogeography are still poorly known. Our LA-ICP-MS U-Pb zircon data, supported by geochemical studies of these rocks, show that paragneisses and quartzites in the Desná and Keprník domes stemmed from sedimentary basin(s) whose the maximum depositional age is c. 560–570 Ma. Detritus was mainly supplied from Cryogenian-Ediacaran source areas. Precambrian mica schists of the inner Velké Vrbno Dome had mainly Mesoproterozoic detrital component. The accompanied metavolcanics rocks mainly originated as subalkaline E-MORB-like basaltic effusives at c. 610–595 Ma that evolved in the within-plate environments of the retro-arc at the rear of the Ediacaran magmatic arc built of granitoids which were formed at 640–550 Ma. Because the detrital zircon age spectra indicate contributions from the sources bearing 2.2–1.1 Ga components, it is expected that the sedimentation and volcanism presumably occurred at the Amazonian part of the Gondwana mainland. A compilation of new and the existing data further indicates the complex structure of Brunovistulia. The Silesian and Moravian domains of the Brunovistulian superterrane differ in terms of lithology, age of magmatic rock units and isotopic characteristics. The two domains may have developed as different fragments of the same magmatic arc system at the Amazonian margin of peri-Gondwana which evolved for c. 100 Myr. Besides, our new data revealed an early Devonian (408 Ma) onset of volcanism in the westernmost margin of the continental Brunovistulian margin, thus c. 30–40 Ma earlier than the well-known late Devonian volcanism in the Vrbno Group further east.

Provenance of Upper Jurassic–Lower Cretaceous strata in the Mentelle Basin, southwestern Australia, reveals a trans-Gondwanan fluvial pathway

Australia, and East Gondwana more broadly, host extensive Paleozoic–Mesozoic sedimentary basins with thick siliciclastic sequences. These sediments were for the greater part transported by large-scale fluvial systems; however, the spatial and temporal patterns of sediment dispersal remain poorly understood. We investigate the provenance of rift strata in the Mentelle Basin, Western Australia, which were deposited during the Late Jurassic–Early Cretaceous breakup of India from Australia-Antarctica. Monazite U–Pb and zircon U–Pb–Hf isotopic signatures suggest that the Upper Jurassic–Lower Cretaceous syn-rift sediments were supplied predominately by a transcontinental river system draining sediments from interior regions of East Antarctica to the northern Gondwanan passive margin. This fluvial system was focused within the developing rift between India and Australia-Antarctica. Provenance of the transgressive marine post-breakup strata reflects a transition to a proximal sediment source and marks the end of the transcontinental fluvial system after the final breakup of India from Australia-Antarctica in the Valanginian (~136 Ma). Statistical comparison of detrital zircon spectra of Mentelle Basin syn-rift strata with other Australian Paleozoic–Mesozoic rift strata located along our proposed transport route suggests that the transcontinental fluvial pathway was active since the Late Paleozoic. We infer that this fluvial system was one of the principal modes of siliciclastic sediment delivery to rift and passive margin basins of western Australia.

A detrital zircon test of large-scale terrane displacement along the Arctic margin of North America

Abstract Detrital zircon U-Pb geochronology is one of the most common methods used to constrain the provenance of ancient sedimentary systems. Yet, its efficacy for precisely constraining paleogeographic reconstructions is often complicated by geological, analytical, and statistical uncertainties. To test the utility of this technique for reconstructing complex, margin-parallel terrane displacements, we compiled new and previously published U-Pb detrital zircon data (n = 7924; 70 samples) from Neoproterozoic–Cambrian marine sandstone-bearing units across the Porcupine shear zone of northern Yukon and Alaska, which separates the North Slope subterrane of Arctic Alaska from northwestern Laurentia (Yukon block). Contrasting tectonic models for the North Slope subterrane indicate it originated either near its current position as an autochthonous continuation of the Yukon block or from a position adjacent to the northeastern Laurentian margin prior to >1000 km of Paleozoic–Mesozoic translation. Our statistical results demonstrate that zircon U-Pb age distributions from the North Slope subterrane are consistently distinct from the Yukon block, thereby supporting a model of continent-scale strike-slip displacement along the Arctic margin of North America. Further examination of this dataset highlights important pitfalls associated with common methodological approaches using small sample sizes and reveals challenges in relying solely on detrital zircon age spectra for testing models of terranes displaced along the same continental margin from which they originated. Nevertheless, large-n detrital zircon datasets interpreted within a robust geologic framework can be effective for evaluating translation across complex tectonic boundaries.

Recognition of an Early Triassic accretionary complex in the Nedamo Belt of the Kitakami Massif, Northeast Japan: New evidence for correlation with Southwest Japan

AbstractThe Kitakami Massif of the Tohoku district, Northeast Japan, consists mainly of the South Kitakami Belt (Silurian–Cretaceous forearc shallow‐marine sediments, granitoids, and forearc ophiolite) and the North Kitakami Belt (a Jurassic accretionary complex). The Nedamo Belt (a Carboniferous accretionary complex) occurs as a small unit between those two belts. An accretionary unit in the Nedamo Belt is lithologically divided into the Early Carboniferous Tsunatori Unit and the age‐unknown Takinosawa Unit. In order to constrain the accretionary age of the Takinosawa Unit, detrital zircon U–Pb dating was conducted. The new data revealed that the youngest cluster ages from sandstone and tuffaceous rock are 257–248 Ma and 288–281 Ma, respectively. The Early Triassic depositional age of the sandstone may correspond to a period of intense magmatic activity in the eastern margin of the paleo‐Asian continent. A 30–40 my interval between the youngest cluster ages of the sandstone and the tuffaceous rock can be explained by the absence of syn‐sedimentary zircon in the tuffaceous rock. The new detrital zircon data suggest that the Takinosawa Unit can be distinguished as an Early Triassic accretionary complex distinct from the Early Carboniferous Tsunatori Unit. This recognition establishes a long‐duration northeastward younging polarity of accretionary units, from the Carboniferous to Early Cretaceous, in the northern Kitakami Massif. Lithological features and detrital zircon spectra suggest that the Early Triassic Takinosawa Unit in the Nedamo Belt is comparable with the Hisone and Shingai units in the Kurosegawa Belt in Shikoku. The existence of this Early Triassic accretionary complex strongly supports a pre‐Jurassic geotectonic correlation and similarity between Southwest and Northeast Japan.

Sedimentary provenance of the Plio-Pleistocene Nicobar Fan: Complex sourcing revealed through Raman spectroscopy heavy mineral analysis

The Nicobar Fan lies within the north-eastern Indian Ocean between the Ninety-East Ridge and Sunda Arc. The fan forms part of the Bengal–Nicobar Fan System and is among the oldest and largest submarine fans on Earth. Previous U–Pb zircon studies of the Nicobar and Bengal fans indicate the Himalaya as the dominate sediment source, making these fans a major Cenozoic sink for uplifted Himalayan sediment. However, the northwards moving Indian Plate, coupled with mid-Pleistocene collision of the Ninety-East Ridge with the Sunda Arc, has shutdown many sediment pathways linking the Himalaya and Nicobar Fan. Here we use big data Raman spectroscopy heavy mineral analysis along with U–Pb zircon data to better define sediment source regions for the Nicobar Fan during the Plio-Pleistocene following the shutdown of sediment delivery. The detrital zircon spectra for the Plio-Pleistocene Nicobar Fan from this study are consistent with previous work indicating that the original sources of these zircons can be found within both the Greater and Tethyan Himalaya, the Gangdese Arc, and the Indo-Myanmar Ranges. However, the heavy mineral data indicate that a large proportion of sediment has been derived from a more complex array of sources. This is coupled with an abundance of low- and moderate-stability minerals (e.g., amphibole, apatite, clinopyroxene), which are unlikely to have been transported large distances. Suggesting that proximal sources have delivered the majority of lower-stability heavy minerals into the Plio-Pleistocene Nicobar Fan. We show that from the Pleistocene onwards direct sediment delivery into the Nicobar Fan from the Himalaya was largely shutdown, with sediment instead shedding off the uplifting Indo-Myanmar Ranges, the Andaman–Nicobar Accretionary Ridge, and the westwards propagating Ayeyarwady River. This study shows that extensive uplift along the northern Sunda Arc is recorded in the Nicobar Fan alongside the previously reported Himalayan record.

Cordilleran Subduction Initiation: Retroarc Timing and Basinal Response in the Inyo Mountains, Eastern California

Abstract Subduction zones drive plate tectonics on Earth, yet subduction initiation and the related upper plate depositional and structural kinematics remain poorly understood because upper plate records are rare and often strongly overprinted by magmatism and deformation. During the late Paleozoic time, Laurentia’s western margin was truncated by a sinistral strike-slip fault that transformed into a subduction zone. Thick Permian strata in the Inyo Mountains of central-eastern California record this transition. Two basins that were separated by a transpressional antiform contain sedimentary lithofacies that record distinct patterns of shoaling and deepening conditions before and during tectonism associated with subduction initiation. Sandstone petrography and lithofacies analysis show that rocks in a southeastern basin are dominated by carbonate grains derived from adjacent carbonate shelves, whereas sandstones in a northwestern basin are predominantly quartzose with likely derivation from distant ergs or underlying strata. Detrital zircon spectra from all but the youngest strata in both basins are typical of Laurentian continent spectra with prominent peaks that indicate ultimate sources in Appalachia, Grenville, Yavapai/Mazatzal, and the Wyoming or Superior cratons. The first Cordilleran arc-derived detrital zircon grains appear in the uppermost strata of the northwestern basin and record Late Permian (ca. 260 Ma) Cordilleran arc magmatism at this approximate latitude, and a possible source area is suggested by geochemical similarities between these detrital zircons and broadly coeval magmatic zircons in the El Paso Mountains to the southwest. Deformation responsible for basin partitioning is consistent with sinistrally oblique contraction in the earliest Permian time. The data presented from the Inyo Mountains shed more light on the nature of Cordilleran subduction initiation and the upper-crustal response to this transition.