scholarly journals Remote predictive geological mapping as a tool for the reconstruction of the complex geodynamic evolution of Melanesia

2020 ◽  
Author(s):  
Philipp Brandl ◽  
Anna Kraetschell ◽  
Justin Emberley ◽  
Mark Hannington ◽  
Margaret Stewart ◽  
...  
Keyword(s):  
Large Scale ◽  
Solomon Islands ◽  
Sedimentary Cover ◽  
Complete Information ◽  
Geological Mapping ◽  
Geophysical Data ◽  
Geodynamic Evolution ◽  
Predictive Mapping ◽  
Lithostratigraphic Units ◽  
Geological Map

<p>The offshore regions of Eastern Papua New Guinea and the Solomon Islands include several active and remnant arc and backarc systems that formed in response to complex plate tectonic adjustments following subduction initiation in the Eocene. Although there has been extensive exploration for offshore petroleum resources, and more than 54 research cruises have investigated or transited the region since 1993, a comprehensive regional geological map, including the deep marine areas, has not been available at a scale that permits quantitative analysis of the basin history. We present the first map that depicts interpreted assemblage- and formation-level lithostratigraphic units correlated across the marine basins and adjacent land masses. The mapped assemblages and large-scale formations are based on a compilation of land-based geological maps, marine geophysical data (hydroacoustics, magnetics, and gravity) integrated with the results of geological sampling, ocean drilling, seismic surveys, and seabed observations.</p><p>More than 400,000 km<sup>2 </sup>of the map area covered by ship-based multibeam and other geophysical data were inspected to derive the offshore geological units. In areas with limited data, the units were extrapolated from well-documented formations in adjacent regions with more complete information, including on land. This approach follows closely the techniques used for remote predictive mapping in other regions of the Earth where geological information is sparse. Geological boundaries were constrained by ship-based multibeam data reprocessed at 35-m to 50-m resolution and integrated with the Global Multi-Resolution Topography (GMRT) gridded at 100 m. Lithotectonic assemblages were assigned on the basis of plate structure, crustal type and thickness, age, composition, and sedimentary cover and further refined by bathymetric and geophysical data from the literature and cruise reports. The final compilation is generalized and presented here at 1:1 М. Our new approach integrates conventional mapping on land with remote predictive mapping of the ocean floor.</p><p>The newly compiled geological map illustrates the diversity of assemblages in the region and its complex geodynamic evolution. The resolution of our map allows to perform quantitative analyses of area-age relationships and thus crustal growth. Further geoscientific analyses may allow to estimate the regional mineral potential and to delineate permissive areas as future exploration targets.</p>

THE SOCIETY OF ARTS MAP AWARDS AND THE ENCOURAGEMENT OF GEOLOGICAL MAPPING

2018 ◽  
Vol 37 (2) ◽  
pp. 266-292
Author(s):  
C. JOHN HENRY
Keyword(s):  
Large Scale ◽  
Private Enterprise ◽  
High Standard ◽  
Geological Mapping ◽  
Small Scale ◽  
England And Wales ◽  
Ordnance Survey ◽  
Geological Map ◽  
Geological Work

The Society of Arts, recognising the inadequate state of mapping in Britain, introduced an award in 1759 to encourage the accurate survey and production of county maps at a ‘large’ scale of one inch to one mile (1:63,360) by private individuals. From 1761 to 1809, thirteen awards were made. By 1800 nearly all of England and Lowland Scotland and a third of Wales were mapped by the private enterprise of surveyors, cartographers and publishers before the publication in 1801 of the first Ordnance Survey map at an inch to the mile, of Kent. The role of the Society of Arts awards scheme, in the general rush to produce accurate large scale maps of England and Wales is appraised. Manuscript field maps by William Smith and Adam Sedgwick on SA prize-winning county one inch scale maps for their geological work and a completed example of one inch geological mapping by Arthur Aikin are examined. No geological mapping was published on one-inch county maps, but smaller scale reductions were. Less than a third of published large scale county maps won awards and more than half were published without reference to the Society of Arts; however, the rate of progress of survey and publishing suggests that the Society of Arts awards scheme accelerated the trend to produce one inch mapping in England. In the process, the modest accuracy and lack of standardisation demonstrated the need for government intervention. The Ordnance Trigonometric Survey was the government's response in 1791 to produce a rigorous national triangulation and a consistent high standard of national mapping. Published one-inch geological mapping waited until the Ordnance Survey initiated geological mapping in the 1830s. The Society of Arts offered awards for small scale mineralogical maps in 1803; William Smith's 1815 geological map won the award for England and Wales.

scholarly journals Genome Sequence Analysis of First Ross River Virus Isolate from Papua New Guinea Indicates Long-Term, Local Evolution

Viruses ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 482
Author(s):  
Alice Michie ◽  
John S. Mackenzie ◽  
David W. Smith ◽  
Allison Imrie
Keyword(s):  
Papua New Guinea ◽  
Large Scale ◽  
Solomon Islands ◽  
Febrile Illness ◽  
New Guinea ◽  
Recent Common Ancestor ◽  
Ross River Virus ◽  
Most Recent Common Ancestor ◽  
Mean Time

Ross River virus (RRV) is the most medically significant mosquito-borne virus of Australia, in terms of human morbidity. RRV cases, characterised by febrile illness and potentially persistent arthralgia, have been reported from all Australian states and territories. RRV was the cause of a large-scale epidemic of multiple Pacific Island countries and territories (PICTs) from 1979 to 1980, involving at least 50,000 cases. Historical evidence of RRV seropositivity beyond Australia, in populations of Papua New Guinea (PNG), Indonesia and the Solomon Islands, has been documented. We describe the genomic characterisation and timescale analysis of the first isolate of RRV to be sampled from PNG to date. Our analysis indicates that RRV has evolved locally within PNG, independent of Australian lineages, over an approximate 40 year period. The mean time to most recent common ancestor (tMRCA) of the unique PNG clade coincides with the initiation of the PICTs epidemic in mid-1979. This may indicate that an ancestral variant of the PNG clade was seeded into the region during the epidemic, a period of high RRV transmission. Further epidemiological and molecular-based surveillance is required in PNG to better understand the molecular epidemiology of RRV in the general Australasian region.

scholarly journals Large-Scale 3D Modeling and Inversion of Multiphysics Airborne Geophysical Data: A Case Study from the Arabian Shield, Saudi Arabia

Minerals ◽  
2018 ◽  
Vol 8 (7) ◽  
pp. 271 ◽  
Author(s):  
Michael Zhdanov ◽  
Fouzan Alfouzan ◽  
Leif Cox ◽  
Abdulrahman Alotaibi ◽  
Mazen Alyousif ◽  
...  
Keyword(s):  
Saudi Arabia ◽  
3D Modeling ◽  
Large Scale ◽  
Geophysical Data ◽  
Arabian Shield ◽  
Airborne Geophysical Data ◽  
And Inversion

Mapping faults in an urban environment from borehole data (Oviedo, NW Spain)

2021 ◽  
Author(s):  
Luis Pando ◽  
Carlos López-Fernández ◽  
Germán Flor-Blanco ◽  
Sergio Llana-Fúnez
Keyword(s):  
Site Investigation ◽  
Geological Mapping ◽  
City Centre ◽  
Nw Spain ◽  
Regional Literature ◽  
Borehole Data ◽  
Urban Core ◽  
Structural Relationships ◽  
Geotechnical Database ◽  
Lithostratigraphic Units

<p>The detailed geological mapping in built-up areas presents challenges that arise mainly from the covering of outcrops, and the erase of natural geomorphological features during earthmoving works related to urban development. However, it also benefits from the existence of closely spaced site investigation data, including boreholes, not commonly available outside the cities.</p><p>This contribution explains the procedure carried out to improve the interpretation of faults below the city centre of an urban core located in NW Spain. Oviedo is placed on a basin formed by an alternation of sub-horizontal carbonate and siliciclastic formations of Cretaceous age, over which lies an unconformable cover of Paleogene fluvial-lacustrine deposits mostly composed by clays and marls. The paleorelief over which the Paleogene was deposited results in great lateral changes in the thickness of these sediments. Moreover, the basin was deformed during the Alpine convergence in northern Iberia developing an open syncline oriented East-West. During the shortening, a number of minor faults cutting across the gently dipping Cretaceous and Paleogene deposits affect moderately the cartographic pattern of lithostratigraphic units.</p><p>Therefore, this research was focused on the preferential use of information on the ground provided by hundreds of rotary boreholes managed through a GIS-type geotechnical database. The procedure of semiautomatic identification consisted essentially of investigating the spatial variations of the boundary between two Cretaceous formations, in order to find anomalies attributable to fault displacements. In using this boundary as a strain marker for post-depositional deformation, two scales were approached, one aimed at the identification of large faults, and another with greater detail based on trend-surface analysis for fractures of smaller size and local incidence (vertical offset less than 10 m).</p><p>The research has allowed to discuss faults deduced in previous geological maps, helping to interpret thickenings related to the paleorelief, and also to recognize the existence of structures not described in the regional literature. This study provides also better constrains to the analysis of the structural relationships between the faults affecting the Mesozoic-Palaeogene basin, and the Alpine reactivation of the underlying Palaeozoic basement.</p>

Algorithms for constructing structural surfaces by geophysical data based on neural networks

2021 ◽  
Author(s):  
Alexey Shklyaruk ◽  
Kirill Kuznetsov ◽  
David Arutyunyan ◽  
Ivan Lygin
Keyword(s):  
Neural Networks ◽  
Sedimentary Cover ◽  
Geophysical Data ◽  
Seismic Exploration ◽  
Potential Fields ◽  
Magnetic Characteristics ◽  
Test Model ◽  
Functional Relationships ◽  
Gravity And Magnetic ◽  
A Site

<p>At the stage of small and medium-scale geological and geophysical studies, in addition to seismic exploration, methods of potential fields (gravimetry and magnetometry) are usually actively used. These methods, in contrast to the profile seismic observations, taking into account modern satellite and aviation technologies, provide a high-quality areal density and magnetic characteristics of the study area. The main tasks of modern gravimetry and magnetometry include the task of constructing areal models, contrasting in density and magnetization of surfaces. Among a large number of algorithmic solutions, the most effective are methods using an integrated approach, in which seismic data on the morphology of reflecting horizon is used as a reference.</p><p>Reconstruction of the structural surface morphology by geophysical data can be considered as the problem of finding the relationship between the input information (potential fields, geophysical data, and available a priori information) and the desired surface. To assess the dependence, it is proposed to use the reference plots on which both input and output data are presented. Currently, one of the trends in solving such problems is methods based on neural networks. Neural networks can be of various configurations (feedforward networks, radial-basis function networks, backpropagation networks, convolutional networks, etc.), have a different number of layers and neurons.</p><p>In this research, we consider the test and real-world example. A site with a known position of the sedimentary cover bottom is considered as a test model. To verify and compare the algorithms, the gravity and magnetic effects of the layer are calculated. The gravity and magnetic fields were supplied to the input to the algorithms for constructing regression dependence and training the neural network. An incomplete model of the sedimentary cover was supplied to the input for training neural networks. The task was to restore the missing part. The parameter of the standard deviation of the original and reconstructed model was less than 2% for all types of neural networks.</p><p>As a real model, a site was considered where basement cover is only partially available. It was obtained as a result of seismic interpretation. All available geological and geophysical data were used to reconstruct the horizon. Models obtained using reconstruction algorithms can be additional information for further detailed description of the geological structure.</p><p>It should be noted that since neural networks help to find complex functional relationships between field parameters and attributes of the studied environment, they could be used in the tasks of complex interpretation of geological and geophysical data.</p>

Local Graph Edge Partitioning

2021 ◽  
Vol 12 (5) ◽  
pp. 1-25
Author(s):  
Shengwei Ji ◽  
Chenyang Bu ◽  
Lei Li ◽  
Xindong Wu
Keyword(s):  
Real World ◽  
Graph Partitioning ◽  
Large Scale ◽  
Complete Information ◽  
Local Information ◽  
Experimental Results ◽  
Two Stage ◽  
Graph Computation ◽  
Local Graph ◽  
Edge Partitioning

Graph edge partitioning, which is essential for the efficiency of distributed graph computation systems, divides a graph into several balanced partitions within a given size to minimize the number of vertices to be cut. Existing graph partitioning models can be classified into two categories: offline and streaming graph partitioning models. The former requires global graph information during the partitioning, which is expensive in terms of time and memory for large-scale graphs. The latter creates partitions based solely on the received graph information. However, the streaming model may result in a lower partitioning quality compared with the offline model. Therefore, this study introduces a Local Graph Edge Partitioning model, which considers only the local information (i.e., a portion of a graph instead of the entire graph) during the partitioning. Considering only the local graph information is meaningful because acquiring complete information for large-scale graphs is expensive. Based on the Local Graph Edge Partitioning model, two local graph edge partitioning algorithms—Two-stage Local Partitioning and Adaptive Local Partitioning—are given. Experimental results obtained on 14 real-world graphs demonstrate that the proposed algorithms outperform rival algorithms in most tested cases. Furthermore, the proposed algorithms are proven to significantly improve the efficiency of the real graph computation system GraphX.

scholarly journals The Skjoldungen map sheet: completion of the 1:500 000 geological mapping of South-East Greenland

1991 ◽  
Vol 152 ◽  
pp. 30-31
Author(s):  
J.C Escher
Keyword(s):  
Geological Mapping ◽  
The Other ◽  
Geological Survey ◽  
East Greenland ◽  
Metamorphic Development ◽  
Geological Map ◽  
Map Series

The publication of the 1:500 000 Skjoldungen map sheet (Escher, 1990; Fig. 1) marks the completion of the Geological Survey of Greenland's (GGU's) reconnaissance mapping activities in South-East Greenland. A descriptive text to the map is under preparation. All of South-East Greenland between Kap Farvel (59° 00´N) and Mesters Vig (72° 00´N) is now covered by sheets of the 1:500 000 geological map series of Greenland. Five sheets in the series (nos 5,6,9, 10 and 11) remain to be published (Fig. 1); the Thule map sheet (sheet 5) will be printed in the course of 1991, and sheet 10 is under compilation. The presentation of the Skjoldungen map is somewhat different from that of the other 1:500 000 maps inthe series. In addition to traditional lithological information, an effort has been made to show the tectonic/metamorphic development of the region during the Archaean and Proterozoic.

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