Geology of the Newtonmore-Ben Macdui district : Bedrock and superficial geology of the Newtonmore-Ben Macdui district : description for sheet 64 (Scotland)

This report provides an account of the geology of the Newtonmore-Ben Macdui district in the Grampian Highlands of Scotland, which extends from the Cairngorm massif in the north-east, west across to the Upper Spey valley and south into the upper parts of Glen Tilt and Glen Fearnach. The district is nearly all remote countryside with steep-sided glens between upland plateaus with relatively few distinct mountain peaks. The entire area lies within the Cairngorm National Park and much of the land is covered by large estates run for game conservation and recreational sports. The bulk of the rocks are metasedimentary and most of these are assigned to the Neoproterozoic Dalradian Supergroup (Figure 1). In the north-west near Newtonmore, a ridge or ‘palaeohigh’ of older metasedimentary rocks, the Glen Banchor Subgroup, is considered to lie below the Dalradian. The Dalradian Supergroup forms a thick succession of originally clastic, carbonate and pelitic rocks. Much of the latter is graphitic and pelagic in origin. The metasedimentary rocks were intruded by relatively minor basic igneous and granitic bodies as the Rodinian palaeocontinent broke up. At about 470 Ma the Laurentian continental margin collided with an island arc causing the Grampian Event of the Caledonian Orogeny. The orogeny is mainly manifest in four deformation phases which included early large nappe-like folds, ductile shear-zones and prograde Barrovian regional metamorphism. Most of the rocks in this district lie within the kyanite zone but, because most of the rocks are siliceous, this index mineral is scarce. Semipelitic rocks are locally migmatitic. The earlier Precambrian metamorphism in the Glen Banchor Subgroup is overprinted by the Grampian metamorphism

Geology of the Abu Dhabi 1:100 000 map sheet, 100-16, United Arab Emirates

This Sheet Description describes the Quaternary and solid geology of the Abu Dhabi 1:100 000 scale geological map. The Abu Dhabi district covers 3620 km2 along the Arabian Gulf coast including the northern part of Saadiyat island, Abu Dhabi, part of the Mussafah district and many of the islands to the west. These include Futaisi, Bu Kesheishah, Halat al Bharaini, Al Dabiya, Bu Qumah, Bu Shara, Al Qanatir and Al Rafiq. The sheet also includes a significant part of the coastal plain southwest of Abu Dhabi between Shunayyin in the east to Borquat al Rashid in the west, and south to Maharqah, across which the main E11 coastal highway runs. In the southeast of the district, an area of higher ground is formed of Miocene rocks draped by a variable sequence of cemented and unconsolidated dune sand. The region hosts several major oilfields including the Rumaitha, Shanayel, Al Dabb’iya, Umm al Dalkh, Al Mutarib and Umm al Lulu fields. The region is dominated by a series of offshore islands, part of a chain of barrier islands that extend from north of Abu Dhabi to Marawah Island, west of the present area. These islands, along with the sea-ward margin of the coastal plain are mostly comprised of a thin sequence of intensively studied Holocene marine carbonates termed the Abu Dhabi Formation. These sediments represent a transgressive-regressive sequence, and form the classic carbonate-evaporitic ‘sabkhas’ for which the region is justly famous. The Abu Dhabi Formation includes a range of marine and supratidal facies including coastal spits, bars and beach ridges, lagoonal muds, algal mats and ooidal tidal deltas deposited over the last 10 000 years. The southern limit of the Holocene transgression is marked by a beach ridge running parallel to the coast and clearly visible on satellite imagery. The barrier islands commonly have a core of well-cemented Pleistocene carbonate dune sand (Ghayathi Formation) around which the carbonate spits, bars and ridges of the Abu Dhabi Formation were accreted. The islands have been largely deflated down to the local water-table leading to the development of extensive sabkhas. Consequently, the islands are generally flat but punctuated by small Ghayathi Formation mesas and zeugen, forming mushroom-shaped outcrops rising up to 6 m above sea-level, locally capped with marine limestones of the Late Pleistocene Fuwayrit Formation. Offshore to the north of the island, below low water, is the Great Pearl Bank, an area of reefs and coralgal sands named after the former pearling industry in the region. South of the Holocene beach ridge, much of the onshore area is an extensive, very gently sloping coastal plain, dominated by a deflated planation surface developed on either unconsolidated quartzose aeolian sand or well cemented carbonate grainstones of the Ghayathi Formation. The deflation surface is commonly marked by secondary gypsum forming a sabkha. The Ghayathi Formation palaeodunes are locally well exposed, forming spectacular wind-sculpted mesas and zeugen both on the islands and within the lagoons, but also onshore draping the Miocene rocks in the southeast of the district

Geology of the Al Wathba 1:100 000 map sheet, 100-12, United Arab Emirates

This Sheet Description describes the Quaternary and bedrock geology of the Al Wathba 1:100 000 scale geological map. The district covers 2780 km2 southeast of Abu Dhabi island, and includes many of the suburbs of Abu Dhabi city, including the proposed Capital District, Madinat Khalifa A and B, Mussafah, Mohammed bin Zayed City, Mafraq, Bani Yas, Al Wathba, Al Falah, Al Shamka and Abu Dhabi International Airport. The sheet extends east as far as Al Khatim. The pre-Quaternary bedrock comprises Miocene evaporitic mudstone and siltstone of the Gachsaran Formation (Fars Group) overlain by the dolomitic conglomerates, sandstones and siltstones of the Barzaman Formation in the north. In the south and west, the Gachsaran Formation is overlain by the dolomites and limestones of the Dam Formation which forms an escarpment around the Al Dhafra Air Base. These are overlain by the sandstones of the Shuwaihat and Baynunah Formations. Borehole evidence suggests there is a gradation from interbedded siltstones and sandstones of the Baynunah Formation in the west of the district to coarse dolomitic conglomerates of the Barzaman Formation in the north. The Miocene rocks are locally overlain by fluvial sandstones and channel gravels of the Hili Formation which represent Quaternary outwash from the Hajar Mountains to the east. Much of the region is partially covered by pale carbonate aeolianites of the Ghayathi Formation, themselves often covered in a veneer of more recent aeolian sand. These are well exposed near the coast in spectacular zeugen and inland, they form a series of east-northeast trending linear ridges. Modern pale carbonate-dominated low dunes occur particularly in the west of the district. The coastal zone is dominated by a range of Late Pleistocene to Holocene littoral and marine deposits, which comprise the Abu Dhabi Formation. These include coastal spits and bars, algal mats, mangrove swamps and intertidal sediments. Sabkha is developed on the surface of these deposits. The region has seen major development over the past 30 years, which has radically changed the surface geology. Much of the coastal strip has been reclaimed or developed, with a variable amount of made ground, often composed of carbonate sand dredged from the neighbouring lagoons. Further inland, many areas have been extensively landscaped, with large areas of dunes levelled flat or quarried for fill. Much of the north-western part of the sheet is either developed or scheduled for development. Extensive areas of forestry occur along the line of the main Abu Dhabi – Al Ain highway and north of Abu Dhabi International Airport

Nearby quasar remnants and ultra-high energy cosmic rays

As recently suggested, nearby quasar remnants are plausible sites of black-hole based compact dynamos that could be capable of accelerating ultra-high energy cosmic rays (UHECRs). In such a model, UHECRs would originate at the nuclei of nearby dead quasars, those in which the putative underlying supermassive black holes are suitably spun-up. Based on galactic optical luminosity, morphological type, and redshift, we have compiled a small sample of nearby objects selected to be highly luminous, bulge-dominated galaxies, likely quasar remnants. The sky coordinates of these galaxies were then correlated with the arrival directions of cosmic rays detected at energies $> 40$ EeV. An apparently significant correlation appears in our data. This correlation appears at closer angular scales than those expected when taking into account the deflection caused by typically assumed IGM or galactic magnetic fields over a charged particle trajectory. Possible scenarios producing this effect are discussed, as is the astrophysics of the quasar remnant candidates. We suggest that quasar remnants be also taken into account in the forthcoming detailed search for correlations using data from the Auger Observatory.Comment: 2 figures, 4 tables, 11 pages. Final version to appear in Physical Review

Star Formation and Dynamics in the Galactic Centre

The centre of our Galaxy is one of the most studied and yet enigmatic places in the Universe. At a distance of about 8 kpc from our Sun, the Galactic centre (GC) is the ideal environment to study the extreme processes that take place in the vicinity of a supermassive black hole (SMBH). Despite the hostile environment, several tens of early-type stars populate the central parsec of our Galaxy. A fraction of them lie in a thin ring with mild eccentricity and inner radius ~0.04 pc, while the S-stars, i.e. the ~30 stars closest to the SMBH (<0.04 pc), have randomly oriented and highly eccentric orbits. The formation of such early-type stars has been a puzzle for a long time: molecular clouds should be tidally disrupted by the SMBH before they can fragment into stars. We review the main scenarios proposed to explain the formation and the dynamical evolution of the early-type stars in the GC. In particular, we discuss the most popular in situ scenarios (accretion disc fragmentation and molecular cloud disruption) and migration scenarios (star cluster inspiral and Hills mechanism). We focus on the most pressing challenges that must be faced to shed light on the process of star formation in the vicinity of a SMBH.Comment: 68 pages, 35 figures; invited review chapter, to be published in expanded form in Haardt, F., Gorini, V., Moschella, U. and Treves, A., 'Astrophysical Black Holes'. Lecture Notes in Physics. Springer 201

Measurement of the partial widths of the Z into up- and down-type quarks

Using the entire OPAL LEP1 on-peak Z hadronic decay sample, Z -> qbarq gamma decays were selected by tagging hadronic final states with isolated photon candidates in the electromagnetic calorimeter. Combining the measured rates of Z -> qbarq gamma decays with the total rate of hadronic Z decays permits the simultaneous determination of the widths of the Z into up- and down-type quarks. The values obtained, with total errors, were Gamma u = 300 ^{+19}_{-18} MeV and Gamma d = 381 ^{+12}_{-12} MeV. The results are in good agreement with the Standard Model expectation.Comment: 22 pages, 5 figures, Submitted to Phys. Letts.

Measurement of the Strong Coupling alpha s from Four-Jet Observables in e+e- Annihilation

Data from e+e- annihilation into hadrons at centre-of-mass energies between 91 GeV and 209 GeV collected with the OPAL detector at LEP, are used to study the four-jet rate as a function of the Durham algorithm resolution parameter ycut. The four-jet rate is compared to next-to-leading order calculations that include the resummation of large logarithms. The strong coupling measured from the four-jet rate is alphas(Mz0)= 0.1182+-0.0003(stat.)+-0.0015(exp.)+-0.0011(had.)+-0.0012(scale)+-0.0013(mass) in agreement with the world average. Next-to-leading order fits to the D-parameter and thrust minor event-shape observables are also performed for the first time. We find consistent results, but with significantly larger theoretical uncertainties.Comment: 25 pages, 15 figures, Submitted to Euro. Phys. J.

A measurement of the tau mass and the first CPT test with tau leptons

We measure the mass of the tau lepton to be 1775.1+-1.6(stat)+-1.0(syst.) MeV using tau pairs from Z0 decays. To test CPT invariance we compare the masses of the positively and negatively charged tau leptons. The relative mass difference is found to be smaller than 3.0 10^-3 at the 90% confidence level.Comment: 10 pages, 4 figures, Submitted to Phys. Letts.