Sedimentary development and correlation of Late Quaternary terraces in the Kyrenia Range,northern Cyprus,using a combination of sedimentology and optical luminescence data     

Romesh N. Palamakumbura  Alastair H. F. Robertson  Tim C. Kinnaird  David C. W. Sanderson 《International Journal of Earth Sciences》2016,105(1):439-462

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Implications of U–Pb and Lu–Hf isotopic analysis of detrital zircons for the depositional age,provenance and tectonic setting of the Permian–Triassic Palaeotethyan Karakaya Complex,NW Turkey     

Timur Ustaömer  Petek Ayda Ustaömer  Alastair H. F. Robertson  Axel Gerdes 《International Journal of Earth Sciences》2016,105(1):7-38

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Shallow fault segmentation of the Alpine fault zone,New Zealand revealed from 2- and 3-D GPR surveying     

Alastair F. McClymont  Alan G. Green  Anna Kaiser  Heinrich Horstmeyer  Robert Langridge 《Journal of Applied Geophysics》2010,70(4):343-354

Where they are preserved, landforms that have been truncated and offset by past fault movements provide potentially valuable quantitative data that can be used to estimate slip rates. At such locations, it is important to investigate the fault zone in sufficient detail to understand how displacements are accommodated on individual fault strands. At a site along a northern section of the Alpine fault zone on the South Island of New Zealand, surface mapping of a series of faulted river terraces and channels has revealed a complicated and poorly understood paleoearthquake history. We have acquired high-resolution 2- and 3-D ground-penetrating radar (GPR) data over a large area (~ 500 × 500 m) of the terraces to map along-strike changes in shallow (<20 m) fault zone morphology. By identifying distinct reflection patterns within the topographically migrated 3-D GPR volumes and extrapolating them to the longer and more widely spaced GPR profiles, we determined the subsurface extent of two main structural/depositional facies that were juxtaposed by three left-stepping en-echelon fault strands. Two regions of warped strata are interpreted to result from transpressive folding between the overlapping strands, where displacement is transferred from one fault to the next. We suggest that diffuse deformation between the overlapping fault tips results in anomalously low estimates for horizontal and vertical fault displacements of some geomorphic features.  相似文献   

Seafloor glacial features reveal the extent and decay of the last British Ice Sheet,east of Scotland     

Alastair G. C. Graham  Lidia Lonergan  Martyn S. Stoker 《第四纪科学杂志》2009,24(2):117-138

Three‐dimensional (3D) seismic datasets, 2D seismic reflection profiles and shallow cores provide insights into the geometry and composition of glacial features on the continental shelf, offshore eastern Scotland (58° N, 1–2° W). The relic features are related to the activity of the last British Ice Sheet (BIS) in the Outer Moray Firth. A landsystem assemblage consisting of four types of subglacial and ice marginal morphology is mapped at the seafloor. The assemblage comprises: (i) large seabed banks (interpreted as end moraines), coeval with the Bosies Bank moraine; (ii) morainic ridges (hummocky, push and end moraine) formed beneath, and at the margins of the ice sheet; (iii) an incised valley (a subglacial meltwater channel), recording meltwater drainage beneath former ice sheets; and (iv) elongate ridges and grooves (subglacial bedforms) overprinted by transverse ridges (grounding line moraines). The bedforms suggest that fast‐flowing grounded ice advanced eastward of the previously proposed terminus of the offshore Late Weichselian BIS, increasing the size and extent of the ice sheet beyond traditional limits. Complex moraine formation at the margins of less active ice characterised subsequent retreat, with periodic stillstands and readvances. Observations are consistent with interpretations of a dynamic and oscillating ice margin during BIS deglaciation, and with an extensive ice sheet in the North Sea basin at the Last Glacial Maximum. Final ice margin retreat was rapid, manifested in stagnant ice topography, which aided preservation of the landsystem record. Copyright © 2008 John Wiley & Sons, Ltd.  相似文献   

Introduction to Microwave Remote Sensing     

Alastair J.  Graham 《The Photogrammetric Record》2009,24(126):199-199

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Reconciling Storegga tsunami sedimentation patterns with modelled wave heights: A discussion from the Shetland Isles field laboratory     

Alastair G. Dawson  Sue Dawson  Stein Bondevik  Pedro J. M. Costa  Jon Hill  Iain Stewart 《Sedimentology》2020,67(3):1344-1353

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Liebermannite,KAlSi3O8, a new shock-metamorphic,high-pressure mineral from the Zagami Martian meteorite          下载免费PDF全文

Chi Ma  Oliver Tschauner  John R. Beckett  George R. Rossman  Clemens Prescher  Vitali B. Prakapenka  Hans A. Bechtel  Alastair MacDowell 《Meteoritics & planetary science》2018,53(1):50-61

In this paper, we discuss the occurrence of liebermannite (IMA 2013-128), KAlSi₃O₈, a new, shock-generated, high-pressure tetragonal hollandite-type structure silicate mineral, in the Zagami basaltic shergottite meteorite. Liebermannite crystallizes in space group I4/m with Z = 2, cell dimensions of a = 9.15 ± 0.14 (1σ) Å, c = 2.74 ± 0.13 Å, and a cell volume of 229 ± 19 Å³ (for the type material), as revealed by synchrotron diffraction. In Zagami, liebermannite likely formed via solid-state transformation of primary igneous K-feldspar during an impact event that achieved pressures of ~20 GPa or more. The mineral name is in honor of Robert C. Liebermann, a high-pressure mineral physicist at Stony Brook University, New York, USA.  相似文献   

Stratigraphy,depositional environment,and cultural significance of holocene sediments in patterned wetlands of central Veracruz,Mexico     

Richard J. Hebda  Alfred H. Siemens  Alastair Robertson 《Geoarchaeology》1991,6(1):61-84

The coastal wetlands of Veracruz State, Mexico contain many areas of rectilinearly patterned ground. These are the remains of Prehispanic agricultural complexes. Reconnaissance-level stratigraphic studies were carried out in one such wetland area, the “San Juan Basin,” in order to reconstruct the local environmental history. Basal, well-sorted fine sand, which underlies the basin, was likely deposited in the intertidal and beach zones as marine waters gradually left the San Juan Basin. Progradation of the Rio La Antigua delta on the north and the development of coastal dunes on the east closed the embayment by the mid-Holocene. Thereafter, large volumes of silt and clay were deposited in the basin, in large part during the annual floods of the La Antigua River and other streams. Prehispanic inhabitants dug drainage canals and cultivated the seasonally emergent surface leaving behind artifacts, charcoal, and microfossils of maize. The cultivation destroyed original sedimentary structures and converted the naturally deposited sediment to a massive dark gray silty clay. After the fields were abandoned, they were covered by brown silty peat, but the canals and platforms are still detectable on the surface.  相似文献   

On the occurrence of near syzygies in the solar system     

Alastair J. C. McDonald 《Celestial Mechanics and Dynamical Astronomy》1986,38(2):139-153

This paper derives the average period of occurrence of syzygies (conjunctions and oppositions) ofp planets in unperturbed, coplanar, circular orbits about the sun. Numerical results indicate the reliability of the theory and applications are suggested. For example, the theory is relevant to the search for resonances and near mirror configurations.  相似文献   

Devensian glacial events in Buchan (NE Scotland): A progress report on new OSL dates and their implications     

Alastair M.D. Gemmell  Andrew S. Murray  E.R. Connell 《Quaternary Geochronology》2007,2(1-4):237-242

Optically stimulated luminescence (OSL) dating of a series of glaciofluvial/glaciodeltaic sediments in central Buchan and Aberdeen has recently been undertaken. The aims of this project are to test the chronological model proposed by the most recent regional review and the suggestion that parts of Buchan may have remained ice-free during the last glacial maximum (late marine isotope stage (MIS) 3 and MIS 2 29–15 ka). The preliminary results indicate that during the Devensian (ca. 116–12 ka), extensive areas of Buchan may have been glaciated earlier than previously believed (possibly during MIS 4, 72–60 ka), but parts of the region show no depositional evidence of later glaciation. Some waterlain sediments from the Ugie Valley have yielded OSL ages indicating deposition during MIS 5d to MIS 5a (116–72 ka). We discuss whether the absence of overlying glaciogenic sediments at these locations raises questions about the reliability of the OSL ages or about existing models of the Devensian glaciation of Buchan.  相似文献