Processed seismic data of Cruise SO75 1991

The main purpose of the cruise SO75 from 14th October to 12th November 1991 was to test the new instrumentation of the SONNE and the ship itself for the needs of marine geophysics. The second purpose was the investigation of the crustal structure of the Atlantic Ocean from the Madeira-Torre Rise to the continental slope of Portugal which is conjugate to the margin off Newfoundland being investigated by a previous BGR cruise (Hinz et al., 1989). Methods used were multichannel reflection seismics, gravimetry, magnetics, swath echosounding and sediment echography. The test of the ship and its result is discussed in a separate technical report (Roeser et al., 1991). On two lines crossing the Madeira-Torre Rise we have observed seaward dipping reflector sequences. Their position is conjugate to similar features observed off Newfoundland. Magnetic models for one line show a strong magnetization of the whole reflector sequence. Thus, in analogy to the drilled dipping reflector sequence on the Vøring Plateau, it is likely that it mainly consists of lava flows which were extruded subaerially or in shallow water. In contrast to the dipping reflector sequences found earlier, the newly detected sequences are far away from continental crust. Presumably, at the time of their formation the Midatlantic Ridge was subaerial. Geometrical constraints indicate a compressional regime for the eastern part of the Azores-Gibraltar Fracture Zone. Most prominent expression of this is the Gorringe Bank. Our seismic line across it indicates an overthrusting of oceanic crust, however, it does not show any evidence for a Benioff zone. Therefore, only a small amount of oceanic crust can be subducted until now. We have observed compressional features also in the Tagus Abyssal Plain. Our lines north of the Azores-Gibraltar Fracture Zone did not confirm the weak indications for a continuation of the magnetic anomaly M0 across the fracture zone. The present platetectonic models for this area require therefore a modification. For the definition of the ocean-continent transition in the Iberia Abyssal Plain and for the investigation of the nature of the crust near the transition zone 6 ODP drillsites have been proposed. In response to a request by R.B. Whitmarsh from the Institute of Oceanographic Sciences at Wormley, Godalming, we have carried out the required ODP Site Survey.

Citation proposal
. Processed seismic data of Cruise SO75 1991. https://gdk.gdi-de.org/geonetwork/srv/api/records/27d217f3-9e7e-4661-b687-dad99297243e

Simple

Alternate title: SO75 1991

Date ( Creation ): 1991-11-12

Identifier: e918b264-9d4c-a9c8-5577-f69b77986aa0

Status: completed Completed

Point of contact

Federal Institute for Geosciences and Natural Resources

Stilleweg 2 Hannover 30655

GEMET - INSPIRE themes, version 1.0 ( Theme )

Geologie
geology

GEMET - Concepts, version 2.4 ( Theme )

geophysics
Geophysik
raw material
Rohstoff

Keywords ( Theme )

Marine geology
Meeresgeologie
Seismics
Seismik
Two-dimensional seismic reflection
zweidimensionale Reflektionsseismik

Keywords ( Place )

Nordatlanik
North Atlantic Ocean
Azoren-Gibraltar-Bruchzone
Azores-Gibraltar Fracture Zone
Madeira-Torre-Rücken
Madeira-Torre Rise
Gorringe-Bank

Access constraints: Other restrictions

Use constraints: Other restrictions

Other constraints: Allgemeine Geschäftsbedingungen, siehe http://www.bgr.bund.de/AGB - General terms and conditions, see http://www.bgr.bund.de/AGB_en. Die bereitgestellten Informationen sind bei Weiterverwendung wie folgt zu zitieren: Datenquelle: SO75 1991, (c) BGR, Hannover, 1991

Spatial representation type: Vector

Metadata language: English

Character set: UTF8

Topic category

Geoscientific information

Distribution format

Shapefile (n/a )

Transfer size: 2

OnLine resource: SO75 1991 (Shapefile)
SO75 1991 im Format ESRI Shape

OnLine resource: Karte im BGR-Geoviewer
Karte im BGR-Geoviewer

Hierarchy level: Dataset

Conformance result

Date ( Publication ): 2010-12-08

Explanation: siehe dazu die angegebene Durchführungsbestimmung

Statement: During the period from the 14th October to the 12th November 1991 BGR acquired seismic lines in the Iberian Basin. All lines from SO75-001 to SO75-022 are raw data.