Explore the vast range of titles available.

U–Pb detrital zircon ages (LAM-ICPMS) are reported for 20 greywackes and sandstones from seven major tectono-stratigraphic terranes of the Eastern Province of New Zealand (Cretaceous to Carboniferous) to constrain sediment provenances. Samples are mainly from three time horizons: Late Permian, Late Triassic and Late Jurassic. Age datasets are analysed as percentages in geological intervals, and in histogram and cumulative probability diagrams. The latter discriminate significant zircon age components in terms of terrane, sample stratigraphic age, component age, precision and percentage (of total set). Zircon age distributions from all samples have persistent, large Triassic–Permian, and very few Devonian–Silurian, populations, features which exclude a sediment provenance from the early Palaeozoic, Lachlan Fold Belt of southeast Australia or continuations in New Zealand and Antarctica. In the accretionary terranes, significant Palaeozoic (and Precambrian) zircon age populations are present in Torlesse and Waipapa terranes, and variably in Caples terrane. In the fore-arc and back-arc terranes, a unimodal character persists in Murihiku and Brook Street terranes, while Dun Mountain–Maitai terrane is more variable, and with Caples terrane, displays a hybrid character. Required extensive Triassic–Permian zircon sources can only be found within the New England Fold Belt and Hodgkinson Province of northeast Australia, and southward continuations to Dampier Ridge, Lord Howe Rise and West Norfolk Ridge (Tasman Sea). Small but significant Palaeozoic (and Precambrian) age components in the accretionary terranes (plus Dun Mountain–Maitai terrane), have sources in hinterlands of the New England Fold Belt, in particular to mid-Palaeozoic granite complexes in NE Queensland, and Carboniferous granite complexes in NE New South Wales. Major and minor components place sources (1) for the older Torlesse (Rakaia) terrane, in NE Queensland, and (2) for Waipapa terrane, in NE New South Wales, with Dun Mountain–Maitai and Caples terrane sources more inshore and offshore, respectively. In Early Jurassic–Late Cretaceous, Torlesse (Pahau) and Waipapa terranes, there is less continental influence, and more isolated, offshore volcanic arc sources are suggested. There is local input of plutonic rock detritus into Pahau depocentres from the Median Batholith in New Zealand, or its northward continuation on Lord Howe Rise. Excepting Murihiku and Brook Street terranes, all others are suspect terranes, with depocentres close to the contemporary Gondwanaland margin in NE Australia, and subsequent margin-parallel, tectonic transport to their present New Zealand position. This is highlighted by a slight southeastward migration of terrane depocentres with time. Murihiku and Brook Street terrane sources are more remote from continental influences and represent isolated offshore volcanic depocentres, perhaps in their present New Zealand position.

The Qiangtang terrane is composed of several small blocks that formed since the Rodinia supercontinent period. Previous studies have shown that the Longmu Co-Shuanghu suture zone divides the Qiangtang terrane into the South and North Qiangtang terranes. However, the tectonic affinities and evolution histories of the North and South Qiangtang remain debated. We conducted geochemical and geochronologic analyses on gneiss rocks from the Ningduo and Jitang groups in the North Qiangtang terrane and the Youxi Group in the South Qiangtang terrane. The results of major and trace element analysis indicate the protoliths are lithic arkose, lithic greywacke, and granite (rhyolite), respectively. The isotopic analysis results further suggest that the gneisses have undergone a long-term crustal material cycle and had different ancient crustal source regions. Zircon U-Pb dating results reveal that the detrital zircons from the Ningduo Group are predominantly concentrated in two age ranges: 951-998 Ma and 1100-1148 Ma. The Jitang Group mainly exhibits three distinct age clusters: 226-249 Ma, 952-998 Ma, and 1052-1093 Ma. The Youxi Group mainly displays three prominent ages: 213-249 Ma, 402-449 Ma, and 1055-1098 Ma. These ages indicate that the ancient plate basement has been overprinted by multiple stages of deformation and magmatism and that both the South and North Qiangtang terranes exhibit records of the closure of the paleo-Tethyan Ocean. We propose that the North Qiangtang tends to be Cathaysian provenance, and the South Qiangtang tends to be Gondwana provenance. The investigation of gneiss in this article presents a novel perspective on the tectonic evolution of the Qiangtang area.

The Pearya Terrane, recognized as the only exotic terrane along the Canadian Arctic margin, includes a Neoproterozoic–early Paleozoic basinal or passive-margin metasedimentary sequence that is structurally juxtaposed with arc-related Paleozoic rocks and a metamorphic basement complex containing early Neoproterozoic orthogneiss. The Neoproterozoic siliciclastic sequence is similar to other clastic sections formed at the breakup of Rodinia, but its paleogeographic origin and crustal affinity are uncertain. Detrital zircon age spectra from seven samples reveal three groups: Group A, with numerous peaks at c. 1100–1800 Ma and the youngest population at c. 1020 Ma; Group B, defined by a dominant c. 970 Ma age peak; and Group C, with dominant peaks from c. 970–1800 Ma and a small population of c. 635–710 Ma grains. Spectra from Group A resemble data from the latest Mesoproterozoic units in Svalbard, East Greenland, and the Scandinavian Caledonides, with the ubiquitous Mesoproterozoic ages observed in all these regions compatible with derivation from the Grenville-Sveconorwegian Orogen of Laurentia and Baltica. The dominance of 930–970 Ma ages in Group B reflects input from magmatic rocks of this age in Pearya and Svalbard, while the 635–710 Ma ages observed in Group C overlap with magmatic ages observed in the Arctic Alaska–Chukotka Terrane and units in the Taimyr-Timanide region. The Neoproterozoic siliciclastic strata of the Pearya Terrane originated distal to northeastern Laurentia, in a position similar to that of the constituent terranes of Svalbard and the Eleonore Bay Supergroup of East Greenland, and they record deposition along a Neoproterozoic convergent margin active during the prolonged breakup of Rodinia.

The Archaean Jiaodong Terrane is located in the southern segment of the Palaeoproterozoic Jiao-Liao-Ji Belt, which separates the Eastern Block of the North China Craton into the Longgang and Langrim blocks. Controversy has long surrounded the issue of whether the Jiaodong Terrane is part of the North China Craton or an exotic terrane. This study presents new zircon U-Pb ages for the major lithologies of the Jiaodong Terrane, and the results indicate that the terrane underwent two main magmatic events at approximately 2.89 Ga and 2.62-2.56 Ga and two metamorphic events at approximately 2.5 Ga and 1.9-1.8 Ga. These ages are consistent with those of other metamorphic complexes in the Eastern Block, suggesting that the Jiaodong Terrane was part of the Neoarchaean basement of the Eastern Block, which was reworked at 1.9-1.8 Ga in association with the development of the Palaeoproterozoic Jiao-Liao-Ji Belt.

The Caledonides of Britain and Ireland include terranes attributed to both Laurentian and Gondwanan sources, separated along the Solway line. Gondwanan elements to the south have been variably assigned to the domains Ganderia and East Avalonia. The Midland Platform forms the core of East Avalonia but its provenance is poorly known. Laser ablation split-stream analysis yields information about detrital zircon provenance by providing simultaneous U–Pb and Lu–Hf data from the same ablated volume. A sample of Red Callavia Sandstone from uppermost Cambrian Stage 3 of the Midland Platform yields a U–Pb age spectrum dominated by Neoproterozoic and Palaeoproterozoic sources, resembling those in the Welsh Basin, the Meguma Terrane of Nova Scotia and NW Africa. Initial εHf values suggest that the Neoproterozoic zircon component was derived mainly from crustal sources < 2 Ga, and imply that the more evolved Palaeoproterozoic grains were transported into the basin from an older source terrane, probably the Eburnean Orogen of West Africa. A sample from Cambrian Stage 4 in the Bray Group of the Leinster–Lakesman Terrane shows, in contrast, a distribution of both U–Pb ages and εHf values closely similar to those of the Gander Terrane in Newfoundland and other terranes attributed to Ganderia, interpreted to be derived from the margin of Amazonia. East Avalonia is clearly distinct from Ganderia, but shows evidence for older crustal components not present in West Avalonia of Newfoundland. These three components of the Appalachian–Caledonide Orogen came from distinct sources on the margin of Cambrian Gondwana.

In the south of the Nuuk region of West Greenland our 1980s mapping recognized four Archaean gneiss terranes (Foeringehavn, Tre Brodre, Tasiusarsuaq and Akia terranes) with different protolith ages and separate early tectonothermal histories. Later in the Archaean these were juxtaposed and then experienced the same 2700-2500 Ma tectonothermal events. Here we abandon extrapolation of only these four terranes across the whole region, and distinguish two new terranes in the NE. The northernmost Isukasia terrane (previously regarded as the northernmost exposure of the Foeringehavn terrane) consists of Palaeoarchaean rocks (>3600 Ma) tectonically bounded on its south by the 3075-2960 Ma Kapisilik terrane; these were juxtaposed and metamorphosed together by 2950 Ma. The previously recognized Foeringehavn terrane to the SW is another, separate entity of Palaeoarchaean rocks that was juxtaposed with adjacent terranes only after c. 2800 Ma. Hence in an increasingly complex regional model, there were several mid- to Neoarchaean terrane assembly events, with superimposed \"orogenies\" from c. 2950 Ma until after 2700 Ma. Although the Foeringehavn and Isukasia terranes were incorporated into the later Archaean terrane collage at different times, they might be fragments from a larger Palaeoarchaean complex rifted apart from c. 3500 Ma onwards.

Detrital zircon U–Pb ages in 37 sandstones from late Early – Late Cretaceous marine and non-marine successions across southern Zealandia indicate a provenance from local basement within present-day Zealandia. Samples from Taranaki Basin were derived from Median and Karamea batholith granitoids with transport directions from west to east. Samples from West Coast, Western Southland and Great South basins contain components derived more locally and more variably from Median Batholith and Rahu Suite granitoids and/or the Palaeozoic Buller Terrane. West Coast Basin samples have more plutonic contributions and Great South Basin localities have more Albian-aged (c. 110–100 Ma) zircons. Samples from Canterbury Basin were sourced from Torlesse Composite Terrane basement. The provenance variations are present in both marine and non-marine sandstones and suggest localized watersheds. This fits an interpretation of Late Cretaceous deposition in rift-controlled basins across southern Zealandia during pre-Gondwana break-up regional extension. More speculatively, some additional source areas may have been created at the rifted margins of Zealandia during this break-up.

The Moon has been divided into three terranes: Procellarum KREEP Terrane (PKT), Feldspathic Highland Terrane (FHT), and South Pole-Aitken Terrane (SPAT), using globally measured Th and FeO. Many lunar evolution models have predicted that a lunar magma ocean will produce a residual layer enriched in incompatible elements such as K, REE, and P (i.e., KREEP) in the late age of crystallization; and that the distribution of thorium can be used as a proxy for determining the global distribution of KREEP. The thorium distribution in these three terranes is inhomogeneous. The highest concentration of thorium is in PKT, the medium concentration of thorium is in SPAT, and almost none in FHT. Then what is the specific distribution in each of the terrane and what enlightenment can it tell us? Here we present and describe the detailed thorium distribution in PKT, SPAT, and FHT and provide some information for the origin of asymmetries on the lunar surface.

We map the characteristic signature of the subducting Juan de Fuca and Gorda plates along the entire Cascadia forearc from northern Vancouver Island, Canada, to Cape Mendocino in northern California, USA, using teleseismic receiver functions. The subducting oceanic crustal complex, possibly including subcreted material, is parameterized by three horizons capable of generating mode‐converted waves: a negative velocity contrast at the top of a low velocity zone underlain by two horizons representing positive contrasts. The amplitude of the conversions varies likely due to differences in composition and/or fluid content. We analyzed the slab signature for 298 long‐running land seismic stations, estimated the depth of the three interfaces through inverse modeling and fitted regularized spline surfaces through the station control points to construct a margin‐wide, double‐layered slab model. Crystalline terranes that act as the static backstop appear to form the major structural barrier that controls the slab morphology. Where the backstop recedes landward beneath the Olympic Peninsula and Cape Mendocino, the slab subducts sub‐horizontally, while the seaward‐protruding and thickened Siletz terrane beneath central Oregon causes steepening of the slab. A tight bend in slab morphology south of the Olympic Peninsula coincides with the location of recurring large intermediate depth earthquakes. The top‐to‐Moho thickness of the slab generally exceeds the thickness of the oceanic crust by 2–12 km, suggesting thickening of the slab or underplating of slab material to the overriding North American plate. Plain Language Summary The tectonic Juan de Fuca plate, that underlies the easternmost North Pacific Ocean off‐shore Vancouver Island, Washington, Oregon, and northern California, is being pushed beneath the North American continent by plate tectonics. On its way deep into the Earth, the plate deforms. In this study, we analyze seismograms of distant earthquakes which were recorded within the study area. Through signal and data processing, we decipher information about the location, orientation, and properties of the down‐going oceanic plate beneath the continent. The data show that the plate protrudes shallowly dipping under the continent beneath the Olympic Peninsula (Washington) and Cape Mendocino (California), while it dips down more steeply under central Oregon and Vancouver Island (British Columbia). This configuration suggests that Siletzia, an old and rigid basalt plateau that forms the central part of the study area, controls the shape of the down‐going plate. Furthermore, the oceanic plate appears to significantly thicken at depth, which may indicate that parts of it accumulate at the base of the continent. These results are important to better understand the subduction process and may help to infer the location of the deeper extent of rupture in a future potential strong earthquake. Key Points We model Cascadia subduction stratigraphy as three dipping horizons Slab morphology is controlled by crystalline terrane backstops A near‐ubiquitous ∼2–10 km thick ultralow velocity zone in the tremor zone correlates with the E‐layer

The deformation mode of the Tibetan Plateau is of crucial importance for understanding its construction and extrusion processes, as well as for the assessment of regional earthquake potential. Block motion and viscous flow models have been proposed to describe the deformation field but are not fully supported by modern geophysical observations. The 2021 Mw 7.4 Maduo earthquake, which occurred inside the Songpan-Ganzi terrane (SGT) in central-east Tibet, provides a chance to evaluate the associated deformation mode of the region. We conduct a joint inversion for this earthquake and resolve a bilateral rupture process, which is characterized by super- and subshear rupture velocities, respectively. We interpret this distinct rupture behavior to be the result of the respective slip concentration depths of the two ruptured segments. We analyze geological, seismic, and geodetic evidence and find that the SGT upper crust shows distributed shear deformation and distinct transverse anisotropy, which are associated with folded structures originating from compression of the paleo-Tethys ocean accretional prism realigned by following shear deformation. The SGT receives lateral shear loading from its NS boundary and accommodates a right-step sinistral motion across the terrane boundary faults. The unique tectonic setting of the SGT defines locations and behaviors of internal faulting and strong earthquakes such as the 2021 Maduo earthquake, with the latter occurring on slow-moving faults at intervals of several thousands of years.