| 1. |
- Cawood, Peter A., et al.
(author)
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Neoproterozoic to early Paleozoic extensional and compressional history of East Laurentian margin sequences : The Moine Supergroup, Scottish Caledonides
- 2015
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In: Geological Society of America Bulletin. - 0016-7606 .- 1943-2674. ; 127:3-4, s. 349-371
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Journal article (peer-reviewed)abstract
- Neoproterozoic siliciclastic-dominated sequences are widespread along the eastern margin of Laurentia and are related to rifting associated with the breakout of Laurentia from the supercontinent Rodinia. Detrital zircons from the Moine Supergroup, NW Scotland, yield Archean to early Neoproterozoic U-Pb ages, consistent with derivation from the Grenville-Sveconorwegian orogen and environs and accumulation post–1000 Ma. U-Pb zircon ages for felsic and associated mafic intrusions confirm a widespread pulse of extension-related magmatism at around 870 Ma. Pegmatites yielding U-Pb zircon ages between 830 Ma and 745 Ma constrain a series of deformation and metamorphic pulses related to Knoydartian orogenesis of the host Moine rocks. Additional U-Pb zircon and monazite data, and 40Ar/39Ar ages for pegmatites and host gneisses indicate high-grade metamorphic events at ca. 458–446 Ma and ca. 426 Ma during the Caledonian orogenic cycle.The presence of early Neoproterozoic siliciclastic sedimentation and deformation in the Moine and equivalent successions around the North Atlantic and their absence along strike in eastern North America reflect contrasting Laurentian paleogeography during the breakup of Rodinia. The North Atlantic realm occupied an external location on the margin of Laurentia, and this region acted as a locus for accumulation of detritus (Moine Supergroup and equivalents) derived from the Grenville-Sveconorwegian orogenic welt, which developed as a consequence of collisional assembly of Rodinia. Neoproterozoic orogenic activity corresponds with the inferred development of convergent plate-margin activity along the periphery of the supercontinent. In contrast in eastern North America, which lay within the internal parts of Rodinia, sedimentation did not commence until the mid-Neoproterozoic (ca. 760 Ma) during initial stages of supercontinent fragmentation. In the North Atlantic region, this time frame corresponds to a second pulse of extension represented by units such as the Dalradian Supergroup, which unconformably overlies the predeformed Moine succession.
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| 2. |
- Bird, Anna, et al.
(author)
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A constant Chinese Loess Plateau dust source since the late Miocene
- 2020
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In: Quaternary Science Reviews. - : Elsevier BV. - 0277-3791 .- 1873-457X. ; 227
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Journal article (peer-reviewed)abstract
- The Pliocene-Pleistocene boundary marks a major change in global climate and East Asian monsoon dynamic. However, the role of the global atmospheric dust-cycle over this time is unclear; in particular the degree to which changes in the dust cycle influenced climate change, were driven by climate change, and how these processes interacted. Chinese loess records past dust-cycle history and the influences of aridification and monsoon circulation over the last 40 Ma. Previous work on the Chinese Loess Plateau argue over whether changes in dust source occur at the Pliocene-Pleistocene boundary, or at 1.2 Ma, despite these intervals marking major shifts in monsoon dynamics. We present Sr, Nd and Hf isotope data from multiple sites and show that dust source largely remains unchanged across these boundaries. Shifts in geochemistry are due to changes in grain-size and weathering. While the transport pathway (river, deserts, direct aeolian) is unclear, these tracer isotopes show that dust was dominantly sourced from the Northern Tibetan Plateau, with some input from the local bedrock. This shows that a major established and constant dust source on the Tibetan Plateau has been active and unchanged since late Miocene, despite dramatically changing climate conditions. Changes in loess accumulation are a function of climate change in Tibetan Plateau source regions rather than effects from increased aridification over the Pliocene-Pleistocene boundary.
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| 3. |
- Fenn, Kaja, et al.
(author)
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The provenance of Danubian loess
- 2022
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In: Earth-Science Reviews. - : Elsevier. - 0012-8252 .- 1872-6828. ; 226, s. 103920-
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Journal article (peer-reviewed)abstract
- With one of the largest watersheds in Europe, draining complex geological terrains within the Alps, Bohemian Massif, Carpathians, Dinarides, and the Balkan Mountains, the Danube River valley has long been linked to the formation of thick loess deposits, particularly within the Middle and Lower Danube basins. However, uncertainty over the provenance of loess-palaeosol sequences along the Danube impacts our understanding of sediment generation mechanisms and hinders interpretation of paleoenvironmental proxies preserved in loess. To date, most of the studies investigating loess provenance in Europe have not attempted a standardised characterisation and synthesis of loess deposits with potential source rocks. Further, despite clear links identified between loess and rivers in Asia and Europe, detrital zircons have not yet been used systematically to investigate the relationship between loess and the fluvial sediments of the Danube and its tributaries. Finally, in European loess research, provenance fingerprinting has often been conducted using indirect approaches or bulk sample geochemical analyses, which have been shown to have a limited application in well mixed sedimentary bodies such as loess.This provenance study of loess along the Danube River integrates existing zircon U-Pb ages and Hf datasets for loess, rivers, and bedrock, with new loess zircon U-Pb and Hf results from loess sequences in Croatia, Serbia and Bulgaria. The results show that all surrounding mountain belts (i.e. the Alps, Bohemian Massif, Carpathians, Dinarides Alps, and Balkan Mountains) contribute primary sediment to loess deposits in the Danube valley via its modern tributary network. Critically sedimentary sources remain relatively homogenous along the river, with no apparent major change in source with tributary confluence, further highlighting the role of fluvial transport in homogenising sediment prior to final aeolian deposition. Whilst some small site variations can be observed, they are likely explained by contributions restricted to very local rock outcrops. Moreover, geomorphological results support floodplain sediments as the proximal sediment source and suggest that short-distance aeolian transport dominates sediment delivery to loess sequences, challenging distant sources hypotheses such as major Saharan sources. The identification of sediment sourced from lower elevation regions such as the Bohemian Massif, Dinarides, and Balkans, which did not support ice-caps, suggests that the role of glacial action in silt-size sediment production has been previously exaggerated. Therefore, the glacial and desert loess division inadequately separates and describes sediment generation processes. This research supports and furthers previous work, which suggests “mountain sourced and transported by-rivers” as a more appropriate term for the particles forming loess, at least in the Danube basin.
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| 4. |
- Pointon, Michael A., et al.
(author)
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A Multi-proxy Provenance Study of Late Carboniferous to Middle Jurassic Sandstones in the Eastern Sverdrup Basin and Its Bearing on Arctic Palaeogeographic Reconstructions
- 2022
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In: Geosciences. - : MDPI AG. - 2076-3263. ; 13:1, s. 10-10
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Journal article (peer-reviewed)abstract
- A multi-proxy provenance study of Late Carboniferous to Middle Jurassic sandstones from the eastern Sverdrup Basin was undertaken employing optical petrography and heavy mineral analysis, chemical analysis of apatite, garnet and rutile grains, as well as detrital zircon U–Pb geochronology and Hf isotope analysis. Late Carboniferous to Middle Jurassic strata on the southern basin margin are inferred as being predominantly reworked from Silurian to Devonian strata within the adjacent Franklinian Basin succession. Higher-grade metamorphic detritus appeared during Middle to Late Triassic times and indicates exhumation and erosion of lower (Neoproterozoic to Cambrian) levels within the Franklinian Basin succession and/or a direct detrital input from the Canadian-Greenland Shield. The provenance of northern-derived sediments is more enigmatic owing to the subsequent opening of the Arctic Ocean. Northern-derived Middle Permian to Early Triassic sediments were likely derived from proximal areas of the Chukotkan part of the Arctic Alaska-Chukotka microplate. Late Triassic northern-derived sediments have different detrital zircon U–Pb age spectra from Middle Permian to Early Triassic ones and were likely derived from the Uralian orogenic belt and/or the Arctic Uralides. The loss of this sand input during latest Triassic times is interpreted to reflect drainage reorganisation farther upstream on the Barents Shelf. Middle Jurassic sands in the northern and axial parts of the basin were largely reworked from local northern-derived Late Triassic strata. This may have been facilitated by rift flank uplift of the northern basin margin in response to rifting in the adjacent proto-Amerasia Basin.
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| 5. |
- Riley, Teal R., et al.
(author)
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Cretaceous arc volcanism of Palmer Land, Antarctic Peninsula : Zircon U-Pb geochronology, geochemistry, distribution and field relationships
- 2020
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In: Journal of Volcanology and Geothermal Research. - : Elsevier BV. - 0377-0273 .- 1872-6097. ; 401
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Journal article (peer-reviewed)abstract
- The Cretaceous marks an episode of enhanced magmatism, sedimentation and tectonic processes along the entire proto-Pacific convergent margin of West Gondwana. Cretaceous magmatism across the Antarctic Peninsula is dominated by the intrusive Lassiter Coast intrusive suite which developed as episodic ‘flare-up’ events during the mid-Cretaceous, at a time of increased convergence. Volcanic rocks of this age are poorly defined, as a consequence of limited field observations and an absence of accurate geochronology. Recent field mapping, combined with unpublished field observations has identified a region >10,000 km2 of dominantly subaerial rhyolitic pyroclastic and epiclastic successions from northern Palmer Land of the Antarctic Peninsula. Volcanic successions up to 1500 m in thickness consist of dominantly silicic ignimbrites, lavas, heterolithic breccias and lahar deposits, fed by caldera-forming eruptions. The volcanic rocks of this region were widely considered to be Early Cretaceous in age based on field relationships and early geochronology. New U-Pb zircon ages identify three distinct volcanic episodes during the Late Cretaceous/Early Cenozoic at ~108 Ma, ~93 Ma and ~64 Ma. Lu-Hf data indicate significant proportions of ancient crust in the petrogenesis of the volcanic rocks and the slightly negative εHf values are consistent with a mid-position (~120 km) within the magmatic arc, relative to more juvenile compositions close to the trench.
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| 6. |
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| 7. |
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| 8. |
- Riley, Teal R., et al.
(author)
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Triassic magmatism and metamorphism in the Antarctic Peninsula : Identifying the extent and timing of the Peninsula Orogeny
- 2020
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In: Journal of South American Earth Sciences. - : Elsevier BV. - 0895-9811 .- 1873-0647. ; 103
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Journal article (peer-reviewed)abstract
- The mid to Late Triassic marks an episode of magmatism, deformation and metamorphism along the proto-Pacific margin of the Antarctic Peninsula and Patagonia. Calc-alkaline magmatism at ~227 Ma developed in a convergent margin setting across the central Antarctic Peninsula and North Patagonian Massif. Two distinct deformation and metamorphic events have been identified at ~221 Ma and ~207 Ma based on new U–Pb zircon ages from a metamorphic orthogneiss complex, investigated for the first time, from the elevated plateau region of central Palmer Land. These two events are interpreted to date the timing of the multi-phase Peninsula Orogeny, which correlates with the Chonide Event of central Patagonia. The onset of deformation in the Antarctic Peninsula is linked to tectonic events in central Patagonia and is associated with non-collisional slab dynamic processes during flat slab subduction in the Late Triassic. No consistent tectonic regime is evident during the mid-to Late Triassic episodes of deformation and metamorphism, but an initial period of extension/transtension (mid-Triassic) and a compressional regime in the Late Triassic is favoured in the Antarctic Peninsula and Patagonia. The newly acquired metamorphic ages provide no clear evidence for a segmented terrane model for the Antarctic Peninsula, as Late Triassic metamorphic ages are identified from across the central and eastern domains. New U–Pb zircon ages are also presented from a suite of strongly foliated granitoids that cross-cut the Triassic orthogneisses. They are dated in the interval 140–136 Ma and represent an episode of Early Cretaceous magmatism, transtensional deformation and widespread metamorphism across northwest and central Palmer Land.
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| 9. |
- van Dishoeck, E. F., et al.
(author)
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Triennial Report, International Astronomical Union, Division VI/Commission 34/Working Group Astrochemistry
- 2012
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In: Proceedings of the International Astronomical Union. - 1743-9213 .- 1743-9221. ; 7:Transactions T28A, s. 236-239
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Journal article (other academic/artistic)abstract
- The study of molecules in space, known as astrochemistry or molecular astrophysics, is a rapidly growing field. Molecules exist in a wide range of environments in both gaseous and solid form, from our own solar system to the distant early universe. To astronomers, molecules are indispensable and unique probes of the physical conditions and dynamics of regions in which they are detected, especially the interstellar medium. In particular, the many stages of both low-mass and high-mass star formation are better understood today thanks to the analysis of molecular observations. Molecules can also yield a global picture of the past and present of sources. Moreover, molecules affect their environment by contributing to the heating and cooling processes that occur.
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| 10. |
- Zachary, Ian, et al.
(author)
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Inhibition of bombesin-induced mitogenesis by pertussis toxin : Dissociation from phospholipase C pathway.
- 1987
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In: Biochemical and Biophysical Research Communications - BBRC. - : Academic Press. - 0006-291X .- 1090-2104. ; 146:2, s. 456-463
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Journal article (peer-reviewed)abstract
- Prior incubation of quiescent cultures of Swiss 3T3 cells with pertussis toxin selectively inhibited the stimulation of DNA synthesis induced by peptides of the bombesin family. While pertussis toxin blocked mitogenesis at an early stage in the action of the peptide, the toxin did not impair the rapid stimulation of polyphosphoinositide breakdown, Ca2+ mobilization or activation of protein kinase C promoted by bombesin. Thus, inhibition of bombesin-induced mitogenesis by pertussis toxin can be dissociated from inactivation of the phospholipase C signalling pathway.
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| 11. |
- Zheng, Jia, et al.
(author)
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Establishing metastatic prostate cancer quality indicators using a modified Delphi approach
- 2022
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In: Clinical Genitourinary Cancer. - : Elsevier BV. - 1558-7673. ; 20:2, s. 151-157
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Journal article (peer-reviewed)abstract
- Background: There is variation in the care provided to men with metastatic prostate cancer (mPCa). There has been no previous set of quality indicators (QIs) regarding the management of men with mPCa. The objective of this study is to develop a set of international mPCa-specific QIs, which will enable global benchmarking of quality of care. Materials and methods: Potential QIs were identified through a literature review. Fourteen multidisciplinary mPCa experts (representing medical and radiation oncology, nursing, psychology, palliative care and urology) from eight countries participated in a modified Delphi process, which consisted of two online surveys, one face-to-face meeting and two teleconferences. Panelists were asked to rate each indicator's importance and feasibility on a Likert scale from 1 to 9. Indicators that received median importance and median feasibility scores ≥ 7.5, and a disagreement index <1 for both measures, on the final round of voting were included in the final set. Results: There was consensus on 23 QIs out of total of 662. Four regarding “general management”, 12 “therapies”, three “complications” and four “patient-reported quality of life”. One of the inherent limitations of the Delphi process is that there is a small expert panel involved. Conclusion: The quality indicator set defined by our process for management of men with mPCa will enable greater understanding of the standard and variation of care globally and will promote consistency of good practice. Future directions will include retrospective evaluation for compliance with these indicators, as well as prospective monitoring.
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| 12. |
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