scholarly journals Positive gravity anomaly over the Sydney basin

1989 ◽  
Vol 20 (2) ◽  
pp. 191 ◽  
Author(s):  
I.R. Qureshi
Keyword(s):  
Gravity Anomaly ◽  
Sedimentary Rocks ◽  
Cubic Splines ◽  
The Body ◽  
Western Boundary ◽  
Positive Density ◽  
Crustal Extension ◽  
Isostatic Compensation ◽  
Basement Fault ◽  
Wide Zone

A prominent positive gravity anomaly overlies the Macdonald trough in the Sydney basin. Allowing for isostatic compensation and the effect of sedimentary rocks, the anomaly is determined to have an amplitude of 440 GU (mms-2) and a width of 60 km. The anomaly is smoothed using cubic splines, FFT and IFFT. It is interpreted by a large mafic body of density 2.9 g cm-3 underlying the basin to a depth of 13.5 km. A 12 km wide zone with a small positive density contrast underlies the body within the lower crust.The steep western boundary of the body represents a major basement fault underlying the Lapstone monocline and Kurrajong Fault System.The anomaly is a member of the Meandarra Gravity Ridge which marks a zone of crustal extension within which dominant nature of intrusion is mafic in character.

scholarly journals Associations between Socio-Economic Status and Unfavorable Social Indicators of Child Wellbeing; a Neighbourhood Level Data Design

2021 ◽  
Vol 18 (23) ◽  
pp. 12661
Author(s):  
Minke R. C. van Minde ◽  
Marlou L. A. de Kroon ◽  
Meertien K. Sijpkens ◽  
Hein Raat ◽  
Eric A. P. Steegers ◽  
...  
Keyword(s):  
Economic Status ◽  
Social Indicators ◽  
Cubic Splines ◽  
Repeated Measurements ◽  
The Body ◽  
Full Potential ◽  
Child Wellbeing ◽  
Socio Economic Status ◽  
Level Data ◽  
Health Differences

Background: Living in deprivation is related to ill health. Differences in health outcomes between neighbourhoods may be attributed to neighbourhood socio-economic status (SES). Additional to differences in health, neighbourhood differences in child wellbeing could also be attributed to neighbourhood SES. Therefore, we aimed to investigate the association between neighbourhood deprivation, and social indicators of child wellbeing. Methods: Aggregated data from 3565 neighbourhoods in 390 municipalities in the Netherlands were eligible for analysis. Neighbourhood SES scores and neighbourhood data on social indicators of child wellbeing were used to perform repeated measurements, with one year measurement intervals, over a period of 11 years. Linear mixed models were used to estimate the associations between SES score and the proportion of unfavorable social indicators of child wellbeing. Results: After adjustment for year, population size, and clustering within neighbourhoods and within a municipality, neighbourhood SES was inversely associated with the proportion of ‘children living in families on welfare’ (estimates with two cubic splines: −3.59 [CI: −3.99; −3.19], and −3.00 [CI: −3.33; −2.67]), ‘delinquent youth’ (estimate −0.26 [CI: −0.30; −0.23]) and ‘unemployed youth’ (estimates with four cubic splines: −0.41 [CI: −0.57; −0.25], −0.58 [CI: −0.73; −0.43], −1.35 [−1.70; −1.01], and −0.96 [1.24; −0.70]). Conclusions: In this study using repeated measurements, a lower neighbourhood SES was significantly associated with a higher prevalence of unfavorable social indicators of child wellbeing. This contributes to the body of evidence that neighbourhood SES is strongly related to child health and a child’s ability to reach its full potential in later life. Future studies should consist of larger longitudinal datasets, potentially across countries, and should attempt to take the interpersonal variation into account with more individual-level data on SES and outcomes.

scholarly journals The impact of resolving the Rossby radius at mid-latitudes in the ocean: results from a high-resolution version of the Met Office GC2 coupled model

2016 ◽  
Vol 9 (10) ◽  
pp. 3655-3670 ◽  
Author(s):  
Helene T. Hewitt ◽  
Malcolm J. Roberts ◽  
Pat Hyder ◽  
Tim Graham ◽  
Jamie Rae ◽  
...  
Keyword(s):  
High Resolution ◽  
Coupled Model ◽  
Ocean Model ◽  
The Body ◽  
Western Boundary ◽  
Coupled Models ◽  
Technical Developments ◽  
Enhanced Resolution ◽  
Circumpolar Current ◽  
The Impact

Abstract. There is mounting evidence that resolving mesoscale eddies and western boundary currents as well as topographically controlled flows can play an important role in air–sea interaction associated with vertical and lateral transports of heat and salt. Here we describe the development of the Met Office Global Coupled Model version 2 (GC2) with increased resolution relative to the standard model: the ocean resolution is increased from 1/4 to 1/12° (28 to 9 km at the Equator), the atmosphere resolution increased from 60 km (N216) to 25 km (N512) and the coupling period reduced from 3 hourly to hourly. The technical developments that were required to build a version of the model at higher resolution are described as well as results from a 20-year simulation. The results demonstrate the key role played by the enhanced resolution of the ocean model: reduced sea surface temperature (SST) biases, improved ocean heat transports, deeper and stronger overturning circulation and a stronger Antarctic Circumpolar Current. Our results suggest that the improvements seen here require high resolution in both atmosphere and ocean components as well as high-frequency coupling. These results add to the body of evidence suggesting that ocean resolution is an important consideration when developing coupled models for weather and climate applications.

scholarly journals AUTHIGENIC MINERALS OF VOLCANOGENIC-SEDIMENTARY ROCKS OF THE PALEOZOIC–CENOZOIC AGE OF THE SOUTHERN PRIMORYE

2021 ◽  
Vol 40 (6) ◽  
pp. 100-110
Author(s):  
A.V. Mozherovsky ◽  
Keyword(s):  
Mixed Layer ◽  
Continental Margin ◽  
Sedimentary Rocks ◽  
Sedimentary Basins ◽  
Crustal Extension ◽  
Southern Primorye ◽  
Frequent Change ◽  
Authigenic Minerals ◽  
Volcanic Material ◽  
Sedimentation Basins

Authigenic minerals in volcanogenic-sedimentary and sedimentary rocks of Southern Primorye from Permian to Miocene time have been studied. Corrensite, rectorite, highly ordered mixed-layer differences of the chlorite-smectite (corrensite-like) and mica-smectite (rectorite-like) types, mica, vermiculite-like differences (?), chlorite, defective chlorite, kaolinite, smectite, calcite, and zeolites were found. Such a set of minerals indicates that the sedimentary layer in the studied sedimentary basins could be three to five kilometer thick, and the temperature of their formation is more than 150°C. The formation of the Lower Cretaceous and Paleocene sedimentary strata has similar features, and probably proceeded first in a shallow sea basin setting of the continental margin (rift stage), sometimes under conditions close to evaporitic (presence of corrensite?), with a frequent change of the facial situation from shallow to deep sedimentation, episodic supplies of volcanic material, and gradual deepening of sedimentation basins. It can be assumed that in Early Cretaceous and Paleogene times, a series of discrete sedimentation basins along the northeastern Asia continental margin developed in a single mineralogical, tectonic, and sedimentological regime of crustal extension: minerals accumulated in the sediments, which in the process of epigenesis transformed in the following directions: a) smectite-rectorite-mica; and b) smectite (palygorskite, sepiolite?) - corrensite-chlorite. In the studied sedimentary complexes three mineralogical «layers» are distinguished: 1) chlorite-mica – mica-chlorite (Permian - Cretaceous); 2) transitional from chlorite and mica to smectite - developed are corrensite, rectorite and highly ordered mixed-layer corrensite-like and rectorite-like minerals (Cretaceous - Paleocene-Eocene), and 3) smectite (from Oligocene to the present).

A geophysical model of the Precambrian of the Albany 1:1M sheet, Western Australia, and its relevance to economic geology

1989 ◽  
Vol 20 (2) ◽  
pp. 195
Author(s):  
A. Whitaker
Keyword(s):  
Granite Gneiss ◽  
Western Boundary ◽  
Block Boundary ◽  
The North ◽  
Geophysical Model ◽  
Eastern Zone ◽  
Western Zone ◽  
Dense Zone ◽  
Wide Zone ◽  
East West

In the Albany 1:1M sheet, the 10-50 km wavelength gravity and aeromagnetic anomalies define major boundaries and subdivisions of the Precambrian blocks/provinces and large bodies of granite, while the short wavelength magnetic anomalies define lithological banding and lineaments. The Yilgarn Block in the sheet area is readily subdivided into two major north-northwest to north trending zones of low magnetization separated by a 30 km wide zone of high magnetization. The eastern zone is considered to be due to granite-greenstone terrane, the western boundary of which is located 100 km west of that currently recognised from outcrop geology. The western zone is considered to be due to granite-geiss terrane while the 30 km wide zone between coincides with strongly magnetised granulites. The Albany Province is composed of two structurally distinct east-west trending zones. The southern zone of relatively low magnetization and density coincides with acid gneiss and granites, whereas the highly magnetised, relatively dense zone to the north and west, correlates with highly metamorphosed acid and mafic granulites. Thrusting of the Albany Province during the Mid-Proterozoic has demagnetised and or deformed the margin of the southern Yilgarn Block to at least 50 km north of the block boundary. Throughout the region, significant mineral deposits of Au, Ni, Sn, Ti, and Fe are located within greenstone and high grade metamorphic belts. These belts have characteristic signatures which contrast with extensive areas of relatively homogeneous, low economic mineral potential, granite-gneiss terrane.

The Pontiac problem, Quebec–Ontario, in the light of gravity data

1987 ◽  
Vol 24 (9) ◽  
pp. 1916-1919 ◽  
Author(s):  
J. Kalliokoski
Keyword(s):  
Gravity Anomaly ◽  
Greenstone Belt ◽  
Gravity Data ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Iron Formation ◽  
Bouguer Gravity ◽  
The West ◽  
Abitibi Greenstone Belt ◽  
Uplifted Block

A belt of Archean quartzose metasedimentary gneisses with minor mafic volcanic rocks (the Pontiac Group) lies south of the Blake River and older Archean mafic volcanic rocks of the Abitibi Greenstone Belt, and is separated from them by the Larder Lake – Cadillac Break. To the west of the Pontiac Group, on strike, is the Archean Larder Lake Group of turbidite conglomerate, argillite, limestone, and iron formation with abundant mafic flows and intrusions. These strata also lie south of the Larder Lake – Cadillac Break and south of the Blake River and older Archean mafic volcanic rocks. The western contact between the Pontiac and Larder Lake groups is covered by a narrow north–south strip of Proterozoic Cobalt sedimentary rocks. On the basis of gravity work that compares the Bouguer gravity anomaly gradient across the Cadillac Break with that across the west margin of the Pontiac Group, it is proposed that the Larder Lake and Pontiac groups are separated by a north–south fault and that the Pontiac Group represents a lithologically distinct uplifted block. The Pontiac block may be an Archean terrane.

scholarly journals Gravity analysis of the offset between crustal structure and topography in the Liupan Shan, northeast Tibetan Plateau

2020 ◽  
Vol 72 (1) ◽  
Author(s):  
Zhenyu Wang ◽  
Guangyu Fu
Keyword(s):  
Gravity Anomaly ◽  
Transitional Zone ◽  
Gps Measurements ◽  
The West ◽  
Isostatic Compensation ◽  
Ordos Block ◽  
Effective Elastic Thickness ◽  
Flexural Analysis ◽  
Crustal Density ◽  
Liupan Shan

AbstractDense gravity/GPS measurements collected around the southwest margin of the Ordos Block in 2014 and 2017 were used to obtain three gravity anomaly profiles across the Liupan Shan Mountains. The Liupan Shan is located in a Bouguer gravity anomaly (BGA) transitional zone; however, low BGAs to the west do not correspond to the topography of the Liupan Shan in that region, with a maximum offset of approximately 34 km. This offset is also found in inverted crustal density structures whereby the interface between the upper and lower crust is notably concave to the west of the Liupan Shan. Flexural analysis indicates that the effective elastic thickness is 5 km and the uplift is caused by oblique subduction of surface materials. According to this uplift mechanism, the offset suggests that Liupan Shan migrated eastward following partial isostatic compensation. Therefore, we suggest that Liupan Shan has experienced an uplift–compensation–uplift tectonic process.

Gravity interpretation using the Mellin transform

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 114-122 ◽  
Author(s):  
N. L. Mohan ◽  
L. Anandababu ◽  
S. V. Seshagiri Rao
Keyword(s):  
Circular Cylinder ◽  
Gravity Anomaly ◽  
Mellin Transform ◽  
The Body ◽  
Two Dimensional ◽  
Gravity Effect ◽  
Horizontal Derivative ◽  
Gravity Interpretation ◽  
Body Parameters ◽  
Horizontal Circular Cylinder

The Mellin transform of the gravity effect of a buried sphere and two‐dimensional horizontal circular cylinder, and the first horizontal derivative of the gravity effect of a two‐dimensional thin fault layer are derived. The transformed functions are bounded by two asymptotes. They are analyzed and procedures are formulated excluding the asymptotic regions for the extraction of the body parameters. The application of the Mellin transform is tested on simulated models as well as on two field examples: (1) the Humble Dome gravity anomaly near Houston, USA; and (2) the Louga gravity anomaly, USA.

RAPID COMPUTATION OF GRAVITATIONAL ATTRACTION OF THREE‐DIMENSIONAL BODIES OF ARBITRARY SHAPE

Geophysics ◽  
1960 ◽  
Vol 25 (1) ◽  
pp. 203-225 ◽  
Author(s):  
Manik Talwani ◽  
Maurice Ewing
Keyword(s):  
Gravity Anomaly ◽  
Arbitrary Shape ◽  
High Speed ◽  
Three Dimensional ◽  
Isostatic Compensation ◽  
External Point ◽  
Spherical Earth ◽  
Terrain Corrections ◽  
High Degree ◽  
Special Case

An expression is derived for the gravity anomaly at an external point caused by a horizontal lamina with the boundary of an irregular polygon. This expression is put in a form suitable for computation by a high speed digital computer. By making the number of sides of the polygon sufficiently large, any irregular outline can be closely approximated. Any three dimensional body can be represented by contours. By replacing each contour by a polygonal lamina, the anomaly caused by it can be obtained at any external point. By a system of interpolation between contours combined with a numerical integration the gravity anomaly caused by the three‐dimensional body can be calculated to a high degree of precision. This method may also be used for rapidly computing terrain corrections on a flat earth. By making a small modification it can further be adopted for computing the terrain correction as well as local isostatic compensation on the Airy system up to the external radius of Hayford zone O on a spherical earth. The expression for the anomaly caused by a horizontal polygonal lamina is also obtained for the special case when the sides of the polygon are alternately parallel to the x- and y-axes, that is, the polygonal lamina can be divided into a number of rectangular laminae. A chart is provided for the hand computation of the gravity anomaly in this case.

An interpretation of the gravity anomaly at Warlingham, Surrey

1996 ◽  
Vol 133 (5) ◽  
pp. 619-624
Author(s):  
P. Kearey ◽  
A. M. Rabae
Keyword(s):  
Gravity Anomaly ◽  
Seismic Reflection ◽  
The Body ◽  
Seismic Reflection Profile ◽  
Seismic Reflection Data ◽  
Shaped Body ◽  
The North ◽  
Reflection Data ◽  
Platform Comparison ◽  
Upper Boundary

AbstractAn interpretation of the negative gravity anomaly at Warlingham, Surrey, controlled by a seismic reflection profile and several boreholes, suggest that it may be caused by a wedge-shaped body of lowdensity Upper Palaeozoic rocks. The seismic reflection data suggest that the upper boundary of the body may be thrust-controlled and originated during Variscan compression. The location of the thrusting appears to be controlled by the southern margin of the stable London Platform. Comparison with similar structures of this type elsewhere suggests that the Variscan Front in this area lies just to the north of Warlingham.

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