scholarly journals A geological map of the Scotia Sea area constrained by bathymetry, geological data, geophysical data and seismic tomography models from the deep mantle

2020 ◽  
Vol 210 ◽  
pp. 103391
Author(s):  
Anouk Beniest ◽  
Wouter P. Schellart
Keyword(s):  
Seismic Tomography ◽  
Geophysical Data ◽  
Geological Data ◽  
Scotia Sea ◽  
Deep Mantle ◽  
Geological Map ◽  
Sea Area

Geological mapping in the offshore domain: unravelling the tectonic history of the Scotia Sea

2020 ◽  
Author(s):  
Anouk Beniest ◽  
Wouter P. Schellart
Keyword(s):  
Cross Sections ◽  
Mantle Flow ◽  
The South ◽  
The West ◽  
Scotia Sea ◽  
Scotia Ridge ◽  
History Of ◽  
Geological Map ◽  
Velocity Anomalies ◽  
Sea Area

<p>We produced the first geological map of the Scotia Sea area based on the available geophysical and geological data. Combining magnetic, Bouguer gravity anomaly and high-resolution bathymetric data with geological data from dredged samples allowed us to map lithologies and structural features in this mostly submerged and complex tectonic area. This geological map allowed us to integrate a very inter-disciplinary dataset, thereby reviewing the available data and addressing some of the still persisting geological challenges and controversies in the area.</p><p>One of the most important and persistent discussions is the nature and age of the Central Scotia Sea. We mapped this part of the Scotia Sea as basaltic-andesitic lithology partly covered by thick, oceanic sediments. This differs in lithology from the West and East Scotia Sea, which we mapped as a basaltic lithology. Based on our lithological map, its unusual thickness and the presence of the Ancestral South Sandwich Arc (ASSA, early Oligocene-late Miocene) we argue that Central Scotia Sea has an Eocene to earliest Oligocene age.</p><p>Cross-sections combining the geology, crustal structure and mantle tomography reveal high velocity anomalies and colder mantle material below the structural highs along the South Scotia Ridge (Terror Rise, Pirie Bank, Bruce Bank and Discovery Bank) and below the South Sandwich Islands. We interpreted those as the southern, stagnated part of the subducting slab of the South Sandwich Trench, following the geometry of Jane Basin and the currently active subducting slab at the South Sandwich Trench. Low velocity anomalies are observed below Drake Passage and the East Scotia Sea, which are interpreted as warmer toroidal mantle flow around the slab edges below the Chilean trench and the South Sandwich trench.</p><p>Based on our geological map and integrated cross-sections we propose a multi-phase evolution of the Scotia Sea area with Eocene or older oceanic crust for the Central Scotia Sea. A first wide-rift-phase initiated before 30 Ma in the West Scotia Ridge, Protector Basin, Dove Basin and Jane Basin either as a result of the diverging South American and Antarctic continents and/or due to subduction rollback that commenced soon after subduction initiation that eventually caused the ASSA to form. The first full spreading center developed in the West Scotia Sea, aided by the warmer toroidal mantle flow causing spreading to be abandoned in the other basins (~30 Ma). A second rift phase in the fore-arc, in between the ASSA and the South Sandwich trench (~20 Ma), initiated through a redistribution of far-field forces as a result of continuous trench retreat. The warmer toroidal mantle concentrated on the East Scotia Ridge resulting in the second spreading system (15 Ma), abandoning the West Scotia Ridge spreading system 6-10 Ma.</p><p>We show that it is possible to create a geological map in a very remote area with an extreme environment with the available geological and geophysical data. This new way of producing geological maps in the offshore domain provides a better insight into the geological history of geologically complex areas that are largely submerged.</p>

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>

Aspects of the Geology of the Scotia Arc

1959 ◽  
Vol 96 (6) ◽  
pp. 425-441 ◽  
Author(s):  
D. H. Matthews
Keyword(s):  
Crustal Structure ◽  
Scotia Sea ◽  
Scotia Arc ◽  
The Caribbean ◽  
Sea Area

AbstractA review is given of the geology of the islands of the Scotia Arc. The provenance of the sedimentary materials is considered and it is concluded that the islands probably represent areas with a crustal structure of a continental type. The crustal structure of the Scotia Sea area is briefly compared with that of the Caribbean.

2010 Offshore petroleum exploration release

2010 ◽  
Vol 50 (1) ◽  
pp. 1
Author(s):  
John Hartwell
Keyword(s):  
Water Depth ◽  
Regulatory Framework ◽  
Geophysical Data ◽  
Petroleum Exploration ◽  
Economic Environment ◽  
Geological Data ◽  
Australian Government ◽  
Investment Opportunities ◽  
Offshore Petroleum

The sustainable annual release of quality petroleum exploration acreage, to provide the global petroleum exploration industry with a variety of investment opportunities in Australian waters, is a key objective of the Australian Government. The annual Offshore Petroleum Exploration Acreage Release (Acreage Release) is underpinned by Australia’s stable economic environment and well-established regulatory framework for offshore petroleum activities. The 2010 Acreage Release areas are located across five basins. Release areas have been carefully selected to offer a range of investment opportunities; areas vary in size, known prospectivity, water depth and level of existing geological data and knowledge. Areas are supported by pre-competitive geological and geophysical data and analysis undertaken by Geoscience Australia.

GEOPHYSICAL EXPLORATION OF SOUTHWEST HUNGARY

Geophysics ◽  
1952 ◽  
Vol 17 (2) ◽  
pp. 278-310 ◽  
Author(s):  
Raoul Vajk
Keyword(s):  
Torsion Balance ◽  
Geophysical Data ◽  
Geological Data ◽  
Geological Structures ◽  
Geophysical Exploration ◽  
Geophysical Surveys

Geophysical exploration of an eight million acre oil concession covering southwest Hungary is discussed. During ten years of exploration (1933–1943), about 20,000 torsion balance, 12,000 gravity meter, and 15,000 magnetometer stations were made, and reflection seismograms were recorded at about 2,500 shot points. As a result of this exploration, four oil pools and a gas pool were discovered and a number of geological structures and major faults were located. Gravity, magnetic, and seismic maps showing most of the geophysical data are submitted. Interpretations of the geophysical results, geological data from subsequent drilling, and a schematic tectonic map of southwest Hungary based on the geophysical surveys are also presented.

Hydrologic Imaging of Fractured Rock

1994 ◽  
Vol 353 ◽  
Author(s):  
Kenzi Karasaki ◽  
Andrew Cohen ◽  
Paul Cook ◽  
Barry Freifeld ◽  
Ken Grossenbacher ◽  
...  
Keyword(s):  
Rock Mass ◽  
High Resolution ◽  
Seismic Tomography ◽  
Pressure Transducer ◽  
Fractured Rock ◽  
Geophysical Data ◽  
Pressure Measurements ◽  
Transient Pressure ◽  
Fractured Rock Mass ◽  
Hydrologic Connections

AbstractVarious geophysical and hydrologic tests were conducted in a cluster of nine wells to image the hydrologic connections of a fractured rock mass. Results of intra-borehole flow surveys and cross-hole radar and seismic tomography surveys correlated very well, and indicated that there is a major feature at a depth of 30m. Systematic injection tests were conducted in all nine wells. Three to four intervals in each well were isolated using pneumatic packers. Each interval was equipped with a high resolution pressure transducer. Some 130 injection tests were conducted, and more than 4,100 cross-hole transient pressure measurements were obtained. A computer algorithm was developed to analyze such massive interference data systematically. As a result of the analysis, an image of the fracture connections emerged which is consistent with the geophysical data.

scholarly journals African cratonic lithosphere carved by mantle plumes

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Nicolas Luca Celli ◽  
Sergei Lebedev ◽  
Andrew J. Schaeffer ◽  
Carmen Gaina
Keyword(s):  
Seismic Tomography ◽  
Mantle Plumes ◽  
Large Igneous Provinces ◽  
Deep Mantle ◽  
Igneous Provinces ◽  
Waveform Tomography

AbstractHow cratons, the ancient cores of continents, evolved since their formation over 2.5 Ga ago is debated. Seismic tomography can map the thick lithosphere of cratons, but its resolution is low in sparsely sampled continents. Here we show, using waveform tomography with a large, newly available dataset, that cratonic lithosphere beneath Africa is more complex and fragmented than seen previously. Most known diamondiferous kimberlites, indicative of thick lithosphere at the time of eruption, are where the lithosphere is thin today, implying surprisingly widespread lithospheric erosion over the last 200 Ma. Large igneous provinces, attributed to deep-mantle plumes, were emplaced near all lithosphere-loss locations, concurrently with or preceding the loss. This suggests that the cratonic roots foundered once modified by mantle plumes. Our results imply that the total volume of cratonic lithosphere has decreased since its Archean formation, with the fate of each craton depending on its movements relative to plumes.

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