cometadata/datacite-titles-descriptions-related-identifiers huggingface dataset:
DOI: 10.6084/m9.figshare.3453971.v1
title: New constraints on the timing of partial melting and deformation along the Nyalam section (central Himalaya): implications for extrusion models

description: New structural, U–Th/Pb and Ar/Ar data along the Nyalam section constrain the timing of partial melting, crystallization and deformation in the Greater Himalayan Sequence. Prograde metamorphism was followed by the onset of partial melting at <em>c.</em> 30 Ma. In the central Greater Himalayan Sequence, <em>in situ</em> melts crystallized between 24 and 18 Ma. Subsequent cooling was very fast (<em>c.</em> 200 °C Ma<sup>−1</sup>) and coeval with the emplacement of undeformed dykes that lasted until <em>c.</em> 15 Ma. In the upper Greater Himalayan Sequence, fast cooling continued until <em>c.</em> 13 Ma. Combined with published <em>P</em>–<em>T</em> and thermochronological data from the Langtang and Dudh Kosi valleys, these data imply that: (a) the partial melt zone thinned over time; (b) the end of melting preceded the end of motion on the Main Central Thrust and the South Tibetan Detachment by 6 and 2 Ma, respectively; (c) the South Tibetan Detachment possibly initiated at <em>c.</em> 25 Ma, probably reactivating a pre-existing thrust; and (d) the present-day topography has been established for &lt;6 Ma and focused erosion on the present-day southern slopes of the Himalaya was not active at the time of the exhumation of the Greater Himalayan Sequence. These observations suggest that the Main Central Thrust/South Tibetan Detachment systems are not passive structures induced by focused erosion, as has been suggested previously by some lower crustal channel flow models.
DOI: 10.6084/m9.figshare.3453968
title: Contrasting mechanisms for crustal sulphur contamination of mafic magma: evidence from dyke and sill complexes from the British Palaeogene Igneous Province

description: The addition of crustal sulphur to magma can trigger sulphide saturation, a process fundamental to the development of some Ni–Cu–PGE deposits. In the British Palaeogene Igneous Province, mafic and ultramafic magmas intrude a thick sedimentary sequence offering opportunities to elucidate mechanisms of magma–crust interaction in a setting with heterogeneous S isotope signatures. We present S-isotopic data from sills and dykes on the Isle of Skye. Sharp contrasts exist between variably light δ<sup>34</sup>S in Jurassic sedimentary sulphide (−35‰ to −10‰) and a local pristine magmatic δ<sup>34</sup>S signature of −2.3 ± 1.5‰. Flat-lying sills have restricted δ<sup>34</sup>S (−5‰ to 0‰) whereas steeply dipping dykes are more variable (−0‰ to −2‰). We suggest that the mechanism by which magma is intruded exerts a fundamental control on the degree of crustal contamination by volatile elements. Turbulent flow within narrow, steep magma conduits, discordant to sediments, and developed by brittle extension or dilation have maximum contamination potential. In contrast, sill-like conduits emplaced concordantly to sediments show little contamination by crustal S. The province is prospective for Ni–Cu–PGE mineralization analogous to the sill-hosted Noril’sk deposit, and Cu/Pd ratios of sills and dykes on Skye indicate that magmas had already reached S-saturation before reaching the present exposure level.
DOI: 10.6084/m9.figshare.3453968.v1
title: Contrasting mechanisms for crustal sulphur contamination of mafic magma: evidence from dyke and sill complexes from the British Palaeogene Igneous Province

description: The addition of crustal sulphur to magma can trigger sulphide saturation, a process fundamental to the development of some Ni–Cu–PGE deposits. In the British Palaeogene Igneous Province, mafic and ultramafic magmas intrude a thick sedimentary sequence offering opportunities to elucidate mechanisms of magma–crust interaction in a setting with heterogeneous S isotope signatures. We present S-isotopic data from sills and dykes on the Isle of Skye. Sharp contrasts exist between variably light δ<sup>34</sup>S in Jurassic sedimentary sulphide (−35‰ to −10‰) and a local pristine magmatic δ<sup>34</sup>S signature of −2.3 ± 1.5‰. Flat-lying sills have restricted δ<sup>34</sup>S (−5‰ to 0‰) whereas steeply dipping dykes are more variable (−0‰ to −2‰). We suggest that the mechanism by which magma is intruded exerts a fundamental control on the degree of crustal contamination by volatile elements. Turbulent flow within narrow, steep magma conduits, discordant to sediments, and developed by brittle extension or dilation have maximum contamination potential. In contrast, sill-like conduits emplaced concordantly to sediments show little contamination by crustal S. The province is prospective for Ni–Cu–PGE mineralization analogous to the sill-hosted Noril’sk deposit, and Cu/Pd ratios of sills and dykes on Skye indicate that magmas had already reached S-saturation before reaching the present exposure level.
DOI: 10.6084/m9.figshare.3453965
title: Importance of crustal relamination in origin of the orogenic mantle peridotite–high-pressure granulite association: example from the Náměšť Granulite Massif (Bohemian Massif, Czech Republic)

description: A characteristic association of crustal and mantle rocks is commonly used to decipher processes at the mantle–crust interface of HP–UHP collisional orogenic systems. Also, in the Variscan orogenic root of the Bohemian Massif (the Moldanubian Zone), high-pressure felsic granulites are often accompanied by spinel or garnet peridotites. This association was investigated using petrography, zircon geochronology and whole-rock geochemical data from the Náměšť Granulite Massif. The geochemical signature of the granulite is the same as for other Moldanubian occurrences, suggesting nearly isochemically metamorphosed felsic metaigneous rocks of Saxothuringian provenance. SHRIMP zircon dating yielded two main age maxima, at 395.2 ± 4.4 and 337.2 ± 1.7 Ma, reflecting an Early Devonian protolith and Visean HP metamorphism. As shown by Sr–Nd isotopic data, the variably refertilized harzburgite or depleted lherzolite was variously contaminated by mature crustal material resembling the studied granulites. To account for the origin of these HT–HP rock associations we suggest a new geotectonic model. An eastward continental subduction of Early Palaeozoic felsic metaigneous material of Saxothuringian origin was followed by its relamination at the bottom of the autochthonous lower crust. Ascending felsic granulites derived from the relaminated lower plate material sampled refertilized harzburgites originally formed in a back-arc. The complete assemblage was subsequently exhumed, forming large, diapir-like bodies.
DOI: 10.6084/m9.figshare.3453965.v1
title: Importance of crustal relamination in origin of the orogenic mantle peridotite–high-pressure granulite association: example from the Náměšť Granulite Massif (Bohemian Massif, Czech Republic)

description: A characteristic association of crustal and mantle rocks is commonly used to decipher processes at the mantle–crust interface of HP–UHP collisional orogenic systems. Also, in the Variscan orogenic root of the Bohemian Massif (the Moldanubian Zone), high-pressure felsic granulites are often accompanied by spinel or garnet peridotites. This association was investigated using petrography, zircon geochronology and whole-rock geochemical data from the Náměšť Granulite Massif. The geochemical signature of the granulite is the same as for other Moldanubian occurrences, suggesting nearly isochemically metamorphosed felsic metaigneous rocks of Saxothuringian provenance. SHRIMP zircon dating yielded two main age maxima, at 395.2 ± 4.4 and 337.2 ± 1.7 Ma, reflecting an Early Devonian protolith and Visean HP metamorphism. As shown by Sr–Nd isotopic data, the variably refertilized harzburgite or depleted lherzolite was variously contaminated by mature crustal material resembling the studied granulites. To account for the origin of these HT–HP rock associations we suggest a new geotectonic model. An eastward continental subduction of Early Palaeozoic felsic metaigneous material of Saxothuringian origin was followed by its relamination at the bottom of the autochthonous lower crust. Ascending felsic granulites derived from the relaminated lower plate material sampled refertilized harzburgites originally formed in a back-arc. The complete assemblage was subsequently exhumed, forming large, diapir-like bodies.
DOI: 10.6084/m9.figshare.3453962
title: Metamorphic and age constraints on crustal reworking in the western H.U. Sverdrupfjella: implications for the evolution of western Dronning Maud Land, Antarctica

description: A petrological and metamorphic comparison of Mesoproterozoic metabasic rocks was conducted on the eastern margin of the Archaean Kaapvaal–Grunehogna Craton and the adjacent westernmost Maud Belt (western H.U. Sverdrupfjella), across a major structural discontinuity known as the Pencksökket–Jutulstraumen Discontinuity. Thermodynamic phase diagram modelling of the low- and high-grade metabasaltic assemblages on either side of the discontinuity revealed a difference in peak metamorphic conditions from <em>T</em> = 340 ± 25 to 700 ± 30°C and <em>P</em> = 0.29 ± 0.08 to 0.90 ± 0.10 GPa over an extrapolated orthogonal distance of 32 km across the strike of the discontinuity. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of titanite in a hornblende–plagioclase–quartz corona around garnet yielded a late Pan-African age of 491 ± 27 Ma for high-grade metamorphism in the western H.U. Sverdrupfjella of the Maud Belt. The new petrological and geochronological constraints indicate that peak upper amphibolite-facies conditions were achieved in the western H.U. Sverdrupfjella at <em>c</em>. 500 Ma; namely, <em>c</em>. 70–80 Ma after peak eclogite–high-pressure granulite-facies metamorphism in the eastern H.U. Sverdrupjella. The U–Pb age data argue against previous models that invoke only late Mesoproterozoic (<em>c</em>. 1060–1030 Ma) granulite-facies metamorphism in the western H.U. Sverdrupfjella and Kaapvaal–Grunehogna Craton margin, and support the concept of a major diachronous Pan-African orogenic episode. A new geodynamic model is presented for western Dronning Maud Land, involving earliest Pan-African eclogite–high-pressure granulite- and upper amphibolite-facies metamorphism in a separate eastern H.U. Sverdrupjella terrane between <em>c</em>. 565 and 540 Ma, followed by later diachronous tectonic accretion of the eastern H.U. Sverdrupjella arc segment onto the western H.U. Sverdrupfjella crustal segment (including the easternmost Kaapvaal–Grunehogna Craton margin) that involved only upper amphibolite-facies metamorphism at <em>c</em>. 500 Ma. The new petrological data indicate that the inferred sub-glacial boundary (Pencksökket–Jutulstraumen Discontinuity) between the Kaapvaal–Grunehogna Craton and the western H.U. Sverdrupfjella region represents a major cratonic Pan-African thrust, which was subsequently reactivated by normal faulting during Gondwana break-up.
DOI: 10.6084/m9.figshare.3453962.v1
title: Metamorphic and age constraints on crustal reworking in the western H.U. Sverdrupfjella: implications for the evolution of western Dronning Maud Land, Antarctica

description: A petrological and metamorphic comparison of Mesoproterozoic metabasic rocks was conducted on the eastern margin of the Archaean Kaapvaal–Grunehogna Craton and the adjacent westernmost Maud Belt (western H.U. Sverdrupfjella), across a major structural discontinuity known as the Pencksökket–Jutulstraumen Discontinuity. Thermodynamic phase diagram modelling of the low- and high-grade metabasaltic assemblages on either side of the discontinuity revealed a difference in peak metamorphic conditions from <em>T</em> = 340 ± 25 to 700 ± 30°C and <em>P</em> = 0.29 ± 0.08 to 0.90 ± 0.10 GPa over an extrapolated orthogonal distance of 32 km across the strike of the discontinuity. Laser ablation inductively coupled plasma mass spectrometry U–Pb dating of titanite in a hornblende–plagioclase–quartz corona around garnet yielded a late Pan-African age of 491 ± 27 Ma for high-grade metamorphism in the western H.U. Sverdrupfjella of the Maud Belt. The new petrological and geochronological constraints indicate that peak upper amphibolite-facies conditions were achieved in the western H.U. Sverdrupfjella at <em>c</em>. 500 Ma; namely, <em>c</em>. 70–80 Ma after peak eclogite–high-pressure granulite-facies metamorphism in the eastern H.U. Sverdrupjella. The U–Pb age data argue against previous models that invoke only late Mesoproterozoic (<em>c</em>. 1060–1030 Ma) granulite-facies metamorphism in the western H.U. Sverdrupfjella and Kaapvaal–Grunehogna Craton margin, and support the concept of a major diachronous Pan-African orogenic episode. A new geodynamic model is presented for western Dronning Maud Land, involving earliest Pan-African eclogite–high-pressure granulite- and upper amphibolite-facies metamorphism in a separate eastern H.U. Sverdrupjella terrane between <em>c</em>. 565 and 540 Ma, followed by later diachronous tectonic accretion of the eastern H.U. Sverdrupjella arc segment onto the western H.U. Sverdrupfjella crustal segment (including the easternmost Kaapvaal–Grunehogna Craton margin) that involved only upper amphibolite-facies metamorphism at <em>c</em>. 500 Ma. The new petrological data indicate that the inferred sub-glacial boundary (Pencksökket–Jutulstraumen Discontinuity) between the Kaapvaal–Grunehogna Craton and the western H.U. Sverdrupfjella region represents a major cratonic Pan-African thrust, which was subsequently reactivated by normal faulting during Gondwana break-up.
DOI: 10.6084/m9.figshare.3453959
title: Structure and sedimentology of George VI Ice Shelf, Antarctic Peninsula: implications for ice-sheet dynamics and landform development

description: Collapse of Antarctic ice shelves in response to a warming climate is well documented, but its legacy in terms of depositional landforms is little known. This paper uses remote-sensing, structural glaciological and sedimentological data to evaluate the evolution of the <em>c</em>. 25000 km<sup>2</sup> George VI Ice Shelf, SW Antarctic Peninsula. The ice shelf occupies a north–south-trending tectonic rift between Alexander Island and Palmer Land, and is nourished mainly by ice streams from the latter region. The structure of the ice shelf is dominated by inherited foliation and fractures, and with velocity data indicates a largely compressive flow regime. The formation of a moraine complex at the margin of the ice shelf is controlled by debris entrained within foliation and folds. This englacial debris is of basal origin, and includes both local Mesozoic sedimentary and volcanic lithologies, and exotic crystalline rocks from Palmer Land. Folding of basal ice to a high level in the source glaciers on Palmer Land is required to bring the debris to the surface. These results have implications for understanding flow dynamics of ice shelves under compressive flow, and debris entrainment and moraine formation associated with palaeo-ice shelves.
DOI: 10.6084/m9.figshare.3453959.v1
title: Structure and sedimentology of George VI Ice Shelf, Antarctic Peninsula: implications for ice-sheet dynamics and landform development

description: Collapse of Antarctic ice shelves in response to a warming climate is well documented, but its legacy in terms of depositional landforms is little known. This paper uses remote-sensing, structural glaciological and sedimentological data to evaluate the evolution of the <em>c</em>. 25000 km<sup>2</sup> George VI Ice Shelf, SW Antarctic Peninsula. The ice shelf occupies a north–south-trending tectonic rift between Alexander Island and Palmer Land, and is nourished mainly by ice streams from the latter region. The structure of the ice shelf is dominated by inherited foliation and fractures, and with velocity data indicates a largely compressive flow regime. The formation of a moraine complex at the margin of the ice shelf is controlled by debris entrained within foliation and folds. This englacial debris is of basal origin, and includes both local Mesozoic sedimentary and volcanic lithologies, and exotic crystalline rocks from Palmer Land. Folding of basal ice to a high level in the source glaciers on Palmer Land is required to bring the debris to the surface. These results have implications for understanding flow dynamics of ice shelves under compressive flow, and debris entrainment and moraine formation associated with palaeo-ice shelves.
DOI: 10.6084/m9.figshare.3453956
title: Late Quaternary beach deposits and archaeological relicts on the coasts of Cyprus, and the possible implications of sea-level changes and tectonics on the early populations

description: Late Pleistocene beach deposits in 22 selected sites around Cyprus demonstrate the vertical changes in the Earth's crust in that island over the last 125 ka. The beach/shallow-marine deposits were observed on the abraded coastal cliffs at 3–22 m above the present sea-level. They overlie Pliocene marls, and some of them contain the Senegalese marine gastropods <em>Persististrombus latus</em>, <em>Bursa granularis</em> and <em>Conus ermineus</em> that no longer live in the Mediterranean. These are index fossils for the Marine Isotope Stage (MIS) 5e in the Mediterranean and, as such, suggest an uplift of up to 15.5 m over about the last 125 ka: that is a maximal rate of 0.12 mm a<sup>−1</sup>. These findings are in accordance with Holocene beachrocks, abrasion platforms, wave notches and Roman/Byzantine fish tanks that retained their elevations, and thus enable the reconstruction of the coast encountered by the early colonizers. While the maximal uplift since the early Holocene has been minor and did not exceed 1.2–1.5 m, the sea-level changes have reached 40–50 m. The transition between the impermeable Pliocene marls and the porous Late Pleistocene deposits above them is the origin of freshwater springs and associated vegetation. The early colonizers seemed to recognize the potential of that essential permanent source of water and excavated wells, the earliest wells known so far. The locations of the Early Neolithic settlements (Mylouthkia and Akanthou) adjacent to visible water springs along the coastal cliffs may not be incidental. Not surprisingly, recent wells dug in the coastal Pleistocene deposits rely on the very same hydrological setting.
DOI: 10.6084/m9.figshare.3453956.v1
title: Late Quaternary beach deposits and archaeological relicts on the coasts of Cyprus, and the possible implications of sea-level changes and tectonics on the early populations

description: Late Pleistocene beach deposits in 22 selected sites around Cyprus demonstrate the vertical changes in the Earth's crust in that island over the last 125 ka. The beach/shallow-marine deposits were observed on the abraded coastal cliffs at 3–22 m above the present sea-level. They overlie Pliocene marls, and some of them contain the Senegalese marine gastropods <em>Persististrombus latus</em>, <em>Bursa granularis</em> and <em>Conus ermineus</em> that no longer live in the Mediterranean. These are index fossils for the Marine Isotope Stage (MIS) 5e in the Mediterranean and, as such, suggest an uplift of up to 15.5 m over about the last 125 ka: that is a maximal rate of 0.12 mm a<sup>−1</sup>. These findings are in accordance with Holocene beachrocks, abrasion platforms, wave notches and Roman/Byzantine fish tanks that retained their elevations, and thus enable the reconstruction of the coast encountered by the early colonizers. While the maximal uplift since the early Holocene has been minor and did not exceed 1.2–1.5 m, the sea-level changes have reached 40–50 m. The transition between the impermeable Pliocene marls and the porous Late Pleistocene deposits above them is the origin of freshwater springs and associated vegetation. The early colonizers seemed to recognize the potential of that essential permanent source of water and excavated wells, the earliest wells known so far. The locations of the Early Neolithic settlements (Mylouthkia and Akanthou) adjacent to visible water springs along the coastal cliffs may not be incidental. Not surprisingly, recent wells dug in the coastal Pleistocene deposits rely on the very same hydrological setting.
DOI: 10.6084/m9.figshare.3453953
title: A major dyke swarm in the Ogaden region south of Afar and the early evolution of the Afar triple junction

description: Geological mapping in the Ogaden region of SE Ethiopia, integrated with aeromagnetic data, has revealed a large dyke swarm extending SSE more than 600 km from the southern Afar margin across the Somali Plate to the Ethiopia–Somalia border. <sup>40</sup>Ar/<sup>39</sup>Ar age dating shows that emplacement occurred at 24–27 Ma, contemporaneous with early rifting and dyking in the Red Sea. Slab-pull forces generated at the Zagros subduction zone strained the lithosphere in the Afro-Arabian plate, and dyking began to extend south from the Red Sea at <em>c.</em> 27 Ma, extending across Afar, fed by a plume-related magma source, rather than the rift-related source prevailing along the Red Sea. Immediately south of the Afar margin, the dyke system was emplaced along the Precambrian Marda Fault Zone, and the continuation across the Ogaden may have been controlled by lithospheric weakness associated with a splay of the Marda Fault. We suggest that the Ogaden Dyke Swarm is a zone of crustal dilation continuing the Red Sea trend across the Horn of Africa and constituting the original third ‘arm’ of the Afar triple junction. Geochemical and geochronological analyses indicate that basaltic outpourings from the Ogaden Dyke Swarm flowed at least as far east as the Ethiopia–Somalia border and emanated from the same magma source as the Ethiopian flood basalts, which had erupted earlier at <em>c.</em> 30 Ma. Dykes are emergent only occasionally and are marked at the surface by linear sand-filled troughs varying from 2 to 20 m deep caused by tensional collapse above the dyke tip. Magnetic anomalies associated with the dykes vary in width up to 1 km and likely identify dyke zones.
DOI: 10.6084/m9.figshare.3453950
title: Geochemical and mineralogical dispersal in till from the Mount Polley Cu-Au porphyry deposit, central British Columbia, Canada

description: The Quesnel terrane in the Interior Plateau of British Columbia, Canada, is highly prospective for locating new porphyry deposits; however, the bedrock in this region is obscured by a nearly continuous blanket of till, making mineral exploration challenging. Located within the Quesnel terrane is the Mount Polley deposit. It is an alkaline, silica-undersaturated, Cu-Au porphyry deposit mined by Imperial Metals Corporation. Eighty-six basal till samples were collected for geochemical and mineralogical analyses in the region of this deposit. Ore elements (Ag, Au and Cu), as well as pathfinder element (Hg and Zn) contents in till reflect detrital glacial dispersal from the Mount Polley deposit. The distribution of anomalous mineral counts of andradite garnet, apatite, chalcopyrite, epidote, jarosite and native gold also reflect glacial dispersal from the deposit. Outcrop-scale ice-flow indicators indicate a dominant ice-flow event to the NW that was preceded by a southwestward glacial advance. The element and mineral signatures of the Mount Polley Cu-Au porphyry deposit are dispersed in sub-glacial surface tills up to 12 km in the down-ice (NW) direction. We demonstrate that till geochemistry and mineralogy can serve for mineral exploration of Cu-Au porphyry mineralization in drift covered areas.