cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3454082
title: The Cadell Fault, southeastern Australia: a record of temporally clustered morphogenic seismicity in a low-strain intraplate region

description: The Cadell Fault, found in stable continental region (SCR) crust in southeastern Australia, provides a record of temporally clustered morphogenic earthquakes spanning much of the Cenozoic. The slip rate, averaged over perhaps as many as five complete seismic cycles in the period 70–20 ka, is <em>c.</em> 0.4–0.5 mm a<sup>−1</sup>, compared with an average rate of <em>c.</em> 0.005–0.01 mm a<sup>−1</sup> over the period spanning the late Miocene to Recent. If full length rupture of the 80 km long feature is assumed, the average recurrence for M<sub>w</sub> 7.3–7.5 earthquake events on the Cadell Fault in the period 70–20 ka is <em>c.</em> 8 kyr. About 20 kyr, representing more than two average seismic cycles, have lapsed since the most recent morphogenic seismic event on the fault. It might therefore be speculated that this fault has relapsed into a quiescent period. Episodic rupture behaviour on the Cadell Fault, and nearby faults in Phanerozoic SCR crust in eastern Australia, might be controlled by their linkage into major crustal fault systems at depth, in apparent contrast with the style of deformation in non-extended Precambrian SCR crust. Periods of strain localization on these major crustal fault systems, effectively turning deforming regions ‘on’ and ‘off’, might be influenced by changes in distant plate boundary forces. If proved, this would have profound consequences for how the occurrence of large earthquakes is assessed in Australia, as the fundamental assumption of morphogenic earthquakes occurring as a result of the progressive build-up of strain, and thus being in some way predictable in their periodicity, is not satisfied. Documenting such fault behaviour in SCR crust assists in conceptualizing the points critical to understanding the hazards posed by SCR faults worldwide.
DOI: 10.6084/m9.figshare.3454082.v1
title: The Cadell Fault, southeastern Australia: a record of temporally clustered morphogenic seismicity in a low-strain intraplate region

description: The Cadell Fault, found in stable continental region (SCR) crust in southeastern Australia, provides a record of temporally clustered morphogenic earthquakes spanning much of the Cenozoic. The slip rate, averaged over perhaps as many as five complete seismic cycles in the period 70–20 ka, is <em>c.</em> 0.4–0.5 mm a<sup>−1</sup>, compared with an average rate of <em>c.</em> 0.005–0.01 mm a<sup>−1</sup> over the period spanning the late Miocene to Recent. If full length rupture of the 80 km long feature is assumed, the average recurrence for M<sub>w</sub> 7.3–7.5 earthquake events on the Cadell Fault in the period 70–20 ka is <em>c.</em> 8 kyr. About 20 kyr, representing more than two average seismic cycles, have lapsed since the most recent morphogenic seismic event on the fault. It might therefore be speculated that this fault has relapsed into a quiescent period. Episodic rupture behaviour on the Cadell Fault, and nearby faults in Phanerozoic SCR crust in eastern Australia, might be controlled by their linkage into major crustal fault systems at depth, in apparent contrast with the style of deformation in non-extended Precambrian SCR crust. Periods of strain localization on these major crustal fault systems, effectively turning deforming regions ‘on’ and ‘off’, might be influenced by changes in distant plate boundary forces. If proved, this would have profound consequences for how the occurrence of large earthquakes is assessed in Australia, as the fundamental assumption of morphogenic earthquakes occurring as a result of the progressive build-up of strain, and thus being in some way predictable in their periodicity, is not satisfied. Documenting such fault behaviour in SCR crust assists in conceptualizing the points critical to understanding the hazards posed by SCR faults worldwide.
DOI: 10.6084/m9.figshare.3454079
title: The planktic foraminifer <em>Planorotalites</em> in the Tethyan middle Eocene

description: Morphologically uniform, low-trochospiral foraminifera are a common, though not very well-preserved component of foraminiferal assemblages across the interval including the Middle Eocene Climatic Optimum (MECO) at the Alano (northeastern Italy) and Monte Cagnero (central Italy) Tethyan sections. The morphology of these specimens, combined with their state of preservation, made it difficult to assign them to a benthic or planktic group. We measured their stable isotope (oxygen and carbon) composition and compared them with those of trochospiral, epifaunal benthic (<em>Nuttallides truempyi</em> (Nuttall, 1930)) and planktic foraminifera (<em>Acarinina</em> and <em>Subbotina</em>) in the same samples. Despite the preservation, the isotopic analysis showed that the low-trochospiral forms were undoubtedly planktic foraminifera calcifying in the mixed layer. We assign them to the species <em>Planorotalites capdevilensis</em> (Cushman & Bermudez, 1949). Their abundance, distribution and stable isotope values suggest that <em>P. capdevilensis</em> may have been mixed-layer dwellers without photosymbionts, adapted to slightly more mesotrophic conditions than symbiont-bearing, larger acarininids and morozovelloidids. The oxygen isotope data for benthic and planktic species in the two sections are similar, but the carbon isotopic values of all foraminifera are 1.0–1.5 lower at the Alano section than at Monte Cagnero, probably because the Alano sediments were deposited in the more restricted Belluno Basin, the Monte Cagnero sediments in the more open oceanic setting of the Umbria-Marche Basin.
DOI: 10.6084/m9.figshare.3454079.v1
title: The planktic foraminifer <em>Planorotalites</em> in the Tethyan middle Eocene

description: Morphologically uniform, low-trochospiral foraminifera are a common, though not very well-preserved component of foraminiferal assemblages across the interval including the Middle Eocene Climatic Optimum (MECO) at the Alano (northeastern Italy) and Monte Cagnero (central Italy) Tethyan sections. The morphology of these specimens, combined with their state of preservation, made it difficult to assign them to a benthic or planktic group. We measured their stable isotope (oxygen and carbon) composition and compared them with those of trochospiral, epifaunal benthic (<em>Nuttallides truempyi</em> (Nuttall, 1930)) and planktic foraminifera (<em>Acarinina</em> and <em>Subbotina</em>) in the same samples. Despite the preservation, the isotopic analysis showed that the low-trochospiral forms were undoubtedly planktic foraminifera calcifying in the mixed layer. We assign them to the species <em>Planorotalites capdevilensis</em> (Cushman & Bermudez, 1949). Their abundance, distribution and stable isotope values suggest that <em>P. capdevilensis</em> may have been mixed-layer dwellers without photosymbionts, adapted to slightly more mesotrophic conditions than symbiont-bearing, larger acarininids and morozovelloidids. The oxygen isotope data for benthic and planktic species in the two sections are similar, but the carbon isotopic values of all foraminifera are 1.0–1.5 lower at the Alano section than at Monte Cagnero, probably because the Alano sediments were deposited in the more restricted Belluno Basin, the Monte Cagnero sediments in the more open oceanic setting of the Umbria-Marche Basin.
DOI: 10.6084/m9.figshare.3454073
title: Theropod dinosaurs from the Middle Jurassic (Bajocian–Bathonian) of Skye, Scotland

description: The Isle of Skye, Scotland, has yielded a diverse Middle Jurassic terrestrial vertebrate fauna, but little is known about the predatory dinosaurs (theropods) occupying the top and secondary carnivore roles in these ecosystems, as their fossils have been limited to rare footprints of small- to mid-sized taxa. We describe two isolated theropod body fossils, a tooth and a middle-posterior caudal vertebra, from the late Bajocian–Bathonian Valtos Sandstone Formation of northeastern Skye, and use a variety of quantitative techniques to determine their taxonomic affinities. We conservatively refer both specimens to Theropoda indet., but suggest that the tooth most likely belonged to a megalosaurid, basal tyrannosauroid, or dromaeosaurid, and that the vertebra belonged to a small-bodied basal coelurosaur of approximately the same size as <em>Coelurus</em> (<em>c</em>. 2 m long, <em>c</em>. 30 kg mass). Although fragmentary, these fossils and the footprints demonstrate that both small and mid to large theropods were present in the Middle Jurassic of Scotland, and that these may have included some of the oldest coelurosaurs, and potentially some of the earliest-diverging tyrannosauroids and dromaeosaurids.
DOI: 10.6084/m9.figshare.3454073.v1
title: Theropod dinosaurs from the Middle Jurassic (Bajocian–Bathonian) of Skye, Scotland

description: The Isle of Skye, Scotland, has yielded a diverse Middle Jurassic terrestrial vertebrate fauna, but little is known about the predatory dinosaurs (theropods) occupying the top and secondary carnivore roles in these ecosystems, as their fossils have been limited to rare footprints of small- to mid-sized taxa. We describe two isolated theropod body fossils, a tooth and a middle-posterior caudal vertebra, from the late Bajocian–Bathonian Valtos Sandstone Formation of northeastern Skye, and use a variety of quantitative techniques to determine their taxonomic affinities. We conservatively refer both specimens to Theropoda indet., but suggest that the tooth most likely belonged to a megalosaurid, basal tyrannosauroid, or dromaeosaurid, and that the vertebra belonged to a small-bodied basal coelurosaur of approximately the same size as <em>Coelurus</em> (<em>c</em>. 2 m long, <em>c</em>. 30 kg mass). Although fragmentary, these fossils and the footprints demonstrate that both small and mid to large theropods were present in the Middle Jurassic of Scotland, and that these may have included some of the oldest coelurosaurs, and potentially some of the earliest-diverging tyrannosauroids and dromaeosaurids.
DOI: 10.6084/m9.figshare.3454061
title: Re-evaluating the geochronology of the Permian Tarim magmatic province: implications for temporal evolution of magmatism

description: The Permian Tarim magmatic province has 118 published ages, ranging from 358 to 205 Ma, but the timing of mafic magmatism is not well constrained. We report two new secondary ion mass spectrometry U–Pb zircon dates on the Halahatang trachydacite and Wajilitag olivine clinopyroxenite, which are 287.2 ± 2.0 Ma and 283.2 ± 2.0 Ma, respectively. The trachydacite overlies the uppermost basalt and constrains the latest eruption age of basalt in northern Tarim. The latter is the first high-resolution date for the Wajilitag mafic layered intrusion. By screening all published ages, we identified 22 robust ages, ranging from 290.9 ± 4.1 to 261.7 ± 1.8 Ma. The robust ages together with our new data reveal a protracted period of mafic magmatism at <em>c</em>. 283 and <em>c</em>. 267 Ma. Silicic magmatism occurred from 291 to 272 Ma. Although the current known volume of Tarim basalt is too small to qualify as a large igneous province, the eroded and intrusive components, as well as pyroclastic deposits and silicic lavas, may increase the estimated volume. Further work is required to refine the duration of magmatism and the volume estimate of the province.
DOI: 10.6084/m9.figshare.3454061.v1
title: Re-evaluating the geochronology of the Permian Tarim magmatic province: implications for temporal evolution of magmatism

description: The Permian Tarim magmatic province has 118 published ages, ranging from 358 to 205 Ma, but the timing of mafic magmatism is not well constrained. We report two new secondary ion mass spectrometry U–Pb zircon dates on the Halahatang trachydacite and Wajilitag olivine clinopyroxenite, which are 287.2 ± 2.0 Ma and 283.2 ± 2.0 Ma, respectively. The trachydacite overlies the uppermost basalt and constrains the latest eruption age of basalt in northern Tarim. The latter is the first high-resolution date for the Wajilitag mafic layered intrusion. By screening all published ages, we identified 22 robust ages, ranging from 290.9 ± 4.1 to 261.7 ± 1.8 Ma. The robust ages together with our new data reveal a protracted period of mafic magmatism at <em>c</em>. 283 and <em>c</em>. 267 Ma. Silicic magmatism occurred from 291 to 272 Ma. Although the current known volume of Tarim basalt is too small to qualify as a large igneous province, the eroded and intrusive components, as well as pyroclastic deposits and silicic lavas, may increase the estimated volume. Further work is required to refine the duration of magmatism and the volume estimate of the province.
DOI: 10.6084/m9.figshare.3454058
title: Some observations on an atypical planktic foraminifer from the Middle Eocene of Kutch, India

description: An atypical planktic foraminifer having close resemblance with <em>Orbulinoides</em> Blow & Saito, 1968 is recorded from a lignite mine section in Kutch, western India. It is practically indistinguishable from <em>Orbulinoides</em> under optical microscope due to general similarities in chamber morphology, coiling mode, aperture number and character, but differs in wall texture when observed under scanning electron microscope (SEM). The wall is characterized by pores of variable size and irregularly distributed pustules unlike the spinose wall of normal <em>Orbulinoides</em>. Based on the SEM micrographs some specialist opinion suggested that the taxon might be a benthic foraminifer. The morphological features of the studied foraminifera are, however, distinctly different from benthic foraminifera with a planktic stage. The associated larger benthic foraminifera correlate the section with the carbonates of Middle Eocene (Bartonian) age in the adjoining areas of Kutch. The accompanying foraminiferal assemblage suggests a near-shore, brackish-water, semi-enclosed depositional environment. It is suggested that the aberrant wall texture was possibly due to environmental stress developed in the restricted basin. Due to incongruous wall texture and to its occurrence as the only planktic foraminifera in the section, the nomenclature of the reported foraminifera is kept open.
DOI: 10.6084/m9.figshare.3454058.v1
title: Some observations on an atypical planktic foraminifer from the Middle Eocene of Kutch, India

description: An atypical planktic foraminifer having close resemblance with <em>Orbulinoides</em> Blow & Saito, 1968 is recorded from a lignite mine section in Kutch, western India. It is practically indistinguishable from <em>Orbulinoides</em> under optical microscope due to general similarities in chamber morphology, coiling mode, aperture number and character, but differs in wall texture when observed under scanning electron microscope (SEM). The wall is characterized by pores of variable size and irregularly distributed pustules unlike the spinose wall of normal <em>Orbulinoides</em>. Based on the SEM micrographs some specialist opinion suggested that the taxon might be a benthic foraminifer. The morphological features of the studied foraminifera are, however, distinctly different from benthic foraminifera with a planktic stage. The associated larger benthic foraminifera correlate the section with the carbonates of Middle Eocene (Bartonian) age in the adjoining areas of Kutch. The accompanying foraminiferal assemblage suggests a near-shore, brackish-water, semi-enclosed depositional environment. It is suggested that the aberrant wall texture was possibly due to environmental stress developed in the restricted basin. Due to incongruous wall texture and to its occurrence as the only planktic foraminifera in the section, the nomenclature of the reported foraminifera is kept open.
DOI: 10.6084/m9.figshare.3454055
title: Middle Ordovician disorganized arc rifting in the peri-Laurentian Newfoundland Appalachians: implications for evolution of intra-oceanic arc systems

description: The Annieopsquotch Accretionary Tract comprises a tectonic collage of Ordovician peri-Laurentian terranes that formed during closure of Iapetus Ocean and imbricated beneath the composite margin of Laurentia. New zircon U–Pb geochronological data (<em>n</em> = 8) for felsic volcanic rocks representing three distinct tectonostratigraphic units (the Mary March Brook group, the Buchans Group and the Red Indian Lake Group) indicate deposition over a short interval between 465 and 462 Ma. These tectonostratigraphic units are characterized by submarine mafic and felsic magmatism, and sedimentation typical of intra-oceanic arc systems. New and compiled whole-rock geochemical (<em>n</em> = 315) and Sm–Nd isotopic (<em>n</em> = 33) data for mafic and felsic volcanic rocks indicate that these tectonostratigraphic units formed in tholeiitic island arc to calc-alkaline arc settings. Isotopic (ε<sub>Nd</sub> −11.2 to +6; T<sub>DM</sub> 1.0–2.4 Ga) and zircon inheritance data (0.5–3.4 Ga) are consistent with presence of Laurentian continental crust in the basement. Relationships within and between these and adjacent tectonostratigraphic units in the Annieopsquotch Accretionary Tract suggest that they represent imbricated slices of a submarine arc that experienced disorganized arc rifting, similar to sectors of the modern Tonga–Kermadec and Izu–Bonin–Mariana arcs. The recognition of disorganized spreading in the Annieopsquotch Accretionary Tract has significant implications for along-strike correlations within the Appalachian orogen, as the nature of the arc systems is expected to differ significantly along-strike. The presence of a clear isotopic and inheritance signature of peri-Laurentian continental crust within the Annieopsquotch Accretionary Tract submarine arc system is consistent with the discoveries of older arc and continental basement in modern intra-oceanic arc systems.
DOI: 10.6084/m9.figshare.3454055.v1
title: Middle Ordovician disorganized arc rifting in the peri-Laurentian Newfoundland Appalachians: implications for evolution of intra-oceanic arc systems

description: The Annieopsquotch Accretionary Tract comprises a tectonic collage of Ordovician peri-Laurentian terranes that formed during closure of Iapetus Ocean and imbricated beneath the composite margin of Laurentia. New zircon U–Pb geochronological data (<em>n</em> = 8) for felsic volcanic rocks representing three distinct tectonostratigraphic units (the Mary March Brook group, the Buchans Group and the Red Indian Lake Group) indicate deposition over a short interval between 465 and 462 Ma. These tectonostratigraphic units are characterized by submarine mafic and felsic magmatism, and sedimentation typical of intra-oceanic arc systems. New and compiled whole-rock geochemical (<em>n</em> = 315) and Sm–Nd isotopic (<em>n</em> = 33) data for mafic and felsic volcanic rocks indicate that these tectonostratigraphic units formed in tholeiitic island arc to calc-alkaline arc settings. Isotopic (ε<sub>Nd</sub> −11.2 to +6; T<sub>DM</sub> 1.0–2.4 Ga) and zircon inheritance data (0.5–3.4 Ga) are consistent with presence of Laurentian continental crust in the basement. Relationships within and between these and adjacent tectonostratigraphic units in the Annieopsquotch Accretionary Tract suggest that they represent imbricated slices of a submarine arc that experienced disorganized arc rifting, similar to sectors of the modern Tonga–Kermadec and Izu–Bonin–Mariana arcs. The recognition of disorganized spreading in the Annieopsquotch Accretionary Tract has significant implications for along-strike correlations within the Appalachian orogen, as the nature of the arc systems is expected to differ significantly along-strike. The presence of a clear isotopic and inheritance signature of peri-Laurentian continental crust within the Annieopsquotch Accretionary Tract submarine arc system is consistent with the discoveries of older arc and continental basement in modern intra-oceanic arc systems.
DOI: 10.6084/m9.figshare.3454049
title: No Exploits back-arc basin in the Iapetus suture zone of Ireland

description: A controversial aspect of the closure history of the Iapetus Ocean concerns the existence of the Exploits basin in Ireland and Britain. The Exploits–Tetagouche back-arc basin of the Canadian Appalachians opened during the Middle Ordovician as the Popelogan–Victoria volcanic arc migrated northwards from the Ganderian margin. The Bellewstown Terrane, within the Iapetus suture zone of Ireland, lies between the Ganderian–Avalonian Leinster Terrane and the Laurentian Grangegeeth Terrane. An early Ordovician ‘Celtic’ shelly fauna is hosted in volcanogenic breccia that we demonstrate is stratigraphically overlain by shales with no volcanic horizons. The lower 24 m of shale are unfossiliferous, but shale above this stratigraphic level has yielded a new graptolite fauna consistent with the upper part of the <em>artus</em> Biozone (Darriwilian, <em>c</em>. 464 Ma). U–Pb zircon dating of the volcanic horizon yields an age of <em>c</em>. 474 Ma. The shale, therefore, appears to represent <em>c</em>. 10 myr of deposition and a significant gap in volcanism. This, together with a Sandbian Anglo-Welsh fauna, suggests that the Bellewstown Terrane remained in a peri-Gondwanan position throughout the Ordovician. Hence, Exploits back-arc basin opening and Ganderian arc migration did not occur in the Irish sector of Iapetus.
DOI: 10.6084/m9.figshare.3454043
title: Reappraisal of Early Cretaceous highly enriched mantle beneath the Dabie Orogen: evidence from mineralogy and geochemistry of the Xiaohekou complex

description: An Early Cretaceous highly enriched mantle beneath the Dabie Orogen, previously proposed on the basis of exceedingly enriched isotopic signatures documented in intermediate–mafic–ultramafic complexes, has been re-evaluated by new field, mineralogical and geochemical data from the best exposed Xiaohekou complex. The Xiaohekou complex consists of three pyroxenite cores intruded by olivine gabbronorite dykes and successively surrounded outward by gabbroic rocks, leucogabbros and monzonites. Textural and compositional data for pyroxenes and plagioclase as well as whole-rock geochemistry suggest two-stage crystallizations. The Sr–Nd isotopic values correlate with the SiO<sub>2</sub> and MgO contents, and one gabbronorite sample from the margin of the complex has sodic plagioclase and highly enriched Sr–Nd isotopic ratios, also pointing to fractional crystallizations and crustal contamination. One gabbro sample from the centre of the complex and three from olivine gabbronorite dykes have the lowest Sr but highest Nd isotopic values close to those of typical Enriched Mantle I (EMI). These data together with isotopic and MELTS modelling suggest that an EMI-like mantle source plus crustal assimilation and crystallization can explain all field, mineralogical and geochemical characteristics of the Xiaohekou complex, without the need to invoke a mantle source more enriched than EMI beneath the Dabie Orogen.