197,825 research outputs found
Cyclic sedimentation in the Southern Alpine Rhaetic: the importance of climate and eustasy in controlling platform‐basin interactions
No full textUppermost Triassic (Rhaetic) facies, as developed in the Southern Alpine region of Northern Italy, were deposited in a rapidly subsiding, fault‐dissected trough (the Lombardy Basin) bounded by carbonate platforms. The main part of the Rhaetic succession consists of 10‐m‐scale asymmetric cycles, each divided into three parts: a lower shale portion; a central rhythmic portion consisting of repeated marl‐limestone couplets, the limestone parts of which thicken upward; and an upper, wholly carbonate unit. A study of the diagenetic history of the series demonstrates that both the major asymmetric cyclicity and the limestone‐marl couplets of the central rhythmic member (together constituting a ‘compound’ cyclic form) are fundamentally depositional in nature. It is suggested that this compound cyclicity resulted from the superposition of a low‐frequency (approximately 100 000‐year periodicity) asymmetric carbonate mud signal with a higher‐frequency terrigenous mud signal. Field, petrographic, and geochemical investigations suggest that the basinal carbonate is predominantly allochthonous in origin, having been derived as relatively pure aragonitic mud from adjacent carbonate platforms. It is postulated that the asymmetric carbonate signal was linked to the ecological effects of eustatic fluctuation on platform carbonate systems. Repeated subaerial exposure of subtidal muds in shallow areas indicates that such sea‐level variations occurred. A model is presented in which the basinward export of carbonate was negligible in the deepening phase, increased to a maximum during shallowing and was finally halted by the emergence of large platform flats. In contrast, the higher frequency terrigenous mud signal of the basin is thought to have been climatically modulated; fluctuations of a shorter period than those predicted by the Milankovitch theory affected hinterland precipitation and runoff. Particularly rapid subsidence and high depositional rates may have allowed the preservation of this signal. Copyright © 1990, Wiley Blackwell. All rights reserve
Asymmetric cycles in the Rhaetic Facies of Southern Alps: Platform-basin interactions governed by eustatic and climatic oscillations
No full textA review of the Upper Triassic source rocks of Italy.
No full textThis is a description of the hydrocarbon potential of Upper Triassic rocks from Italy
Laboratory Studies of Hypervelocity Impacts on Solar System Analogues
Get PDFImpact cratering and asteroid collisions are major processes throughout the Solar System. Although previous collision-related impact investigations exist (Flynn et al. 2015, Holsapple et al. 2002 and Burchell et al. 1998 are good examples), in the works covering this broad range of investigation, the targets are non-rotating (for the purposes of catastrophic disruption) and different temperature conditions are not considered (for impact cratering). Accordingly, I present experimental processes and data, regarding hypervelocity impact experiments into analogues of (1) rotating asteroids and (2) temperature dependant terrestrial planetary rock.
During the course of this work, it was necessary to develop new apparatus and new experimental techniques such as three separate target holders to aid in both catastrophic disruption and heated impact projects, a 3-dimensional model analysis of craters and a completely new, statistically robust, technique to determine a complete crater profile called the KDM method where KDM is Kinnear-Deller-Morris.
The main result from this work showed that during an asteroid impact collision where the asteroid is not rotating, the impact energy density for catastrophic disruption is Q*static = 1442 ± 90 J kg-1. However, when the target asteroid was rotating, the condition Q*rotation = 1097 ± 296 J kg-1. The mean value of Q* had thus reduced, but the spread in the data on individual experiments was larger. This leads to two conclusions. The mean value for Q*, based on measurements of many impacts, falls, due to the internal forces acting in the body which are associated with the rotation. This energy term reduction means that the amount of energy to instigate catastrophic disruption is lower and that a rotating asteroid is effectively weaker upon impact than a stationary asteroid. However, the spread in the results indicates that this is not a uniform process, and an individual result for Q* for a rotating or spinning target may be spread over a large range. For the temperature related impacts, as the targets were heated to approximately 1000 K, the target rocks showed an impact dependence more similar to a plastic phase-state than to solidus, due to being held close to temperatures associated with semi-plastic phases. Basalt impact craters displayed this relationship greatest with crater sizes becoming smaller at the higher temperature ranges but larger in the colder brittle solidus temperatures, partly explained in experiments by increased spallation
Flexicurity as a moderator of the relationship between job insecurity and psychological well-being
Get PDFFlexicurity has been heralded as the solution to simultaneously maintain the well-being of employees through employment security while allowing employers to benefit from flexibility. This paper examines one of the claimed benefits that countries with flexicurity policies will reduce the stress on employees who experience job insecurity. More specifically, it is argued that more generous unemployment benefits along with active labour market policies to facilitate rapid re-employment reduces the anxiety associated with insecurity. Analyses of two international data sets found little evidence for this moderation of the link between insecurity and well-being in countries that are assumed to be exemplars of flexicurity. The economic rationality behind these claims is questioned, and a psychological approach to job insecurity is suggested as an alternative
Trigonoceps occipitalis Burchell 1824
No full textTrigonoceps occipitalis Burchell, 1824 (Fig. 6) LITERATURE. — Green & Sayer (1979); Thonnérieux et al. (1989); Dowsett (1993); Balanca & de Visscher (1997); Weesie & Belemsobgo (1997); Borrow & Demey (2001, 2014); Portier (2002c); Portier et al. (2002); Thiollay (2006a, b); Balanca et al. (2007); Sinclair & Ryan (2010); Dowsett et al. (2013)); Di Vittorio et al. (2018). FIELD DATA. — eBird; GBIF; WABD. STATUS. — Resident; Breeding.Published as part of Boano, Giovanni, Belemsobgo, Urbain, Silvano, Fabrizio, Hema, Emmanuel M., Belemsobgo, Aristide, Dimobe, Kangbéni & Pavia, Marco, 2022, An annotated checklist of the birds of Burkina Faso, pp. 27-107 in Zoosystema 44 (2) on page 57, DOI: 10.5252/zoosystema2022v44a2, http://zenodo.org/record/599969
High Pressure Synthesis, Crystal Growth and Magnetic Properties of TiOF
No full textData to accompany publication; High Pressure Synthesis, Crystal Growth and Magnetic Properties of TiOF J. Cumby, M. B. Burchell and J. P. Attfield Solid State Sciences (2018) Single crystal data files for TiOF at 90 and 200 K. cif files and standard formats used by the SHELX package are provided.Attfield, J Paul; Cumby, J; Burchell, MB. (2018). High Pressure Synthesis, Crystal Growth and Magnetic Properties of TiOF, [dataset]. University of Edinburgh. School of Chemistry. http://dx.doi.org/10.7488/ds/2336
Impact Earth! Protecting the UK and further afield from impacts by Near-Earth objects
No full textMark Burchell, Gareth Collins and Massimiliano Vasile report on an RAS Specialist Discussion Meeting dedicated to investigating the effects of potentially hazardous objects colliding with the Eart
High Pressure Synthesis, Crystal Growth and Magnetic Properties of TiOF
No full textData to accompany publication;
High Pressure Synthesis, Crystal Growth and Magnetic Properties of TiOF
J. Cumby, M. B. Burchell and J. P. Attfield
Solid State Sciences (2018)
Single crystal data files for TiOF at 90 and 200 K. cif files and standard formats used by the SHELX package are provided
- …
