Processed seismic data of Cruise SO137 GINCO I 1998

During RV SONNE cruise 137 from 21st November to 28th December 1998 Geoscientific Investigations on the active Convergence Zone between the east Eurasian and Indo-Australian Plate (GINCO I) were carried out along the Sunda Arc, off Sumatra, Java and the Sunda Strait. The studies were headed by the BGR in close cooperation with German and Indonesian research institutions. A total amount of 5,500 km of magnetic, gravity and swath bathymetric profiles were recorded of which multi-channel seismic data exceeded 4,100 km. The scientific objectives were: (1) investigation of the structure and age of the accretionary wedges, outer arc highs and fore-arc basins off Sumatra and Java with special emphasis on the evolution of the Sunda Strait and the Krakatau area (2) differences in tectonic deformation between oblique (Sumatra) versus frontal (Java) subduction (3) search for oceanic crustal splinters in the accretionary wedges (4) definition of seismic sequences, thicknesses and ages of the fore-arc basin sediments as a pre-requisite for later on hydrocarbon assessments (5) identification and regional occurrence of bottom simulating reflectors (BSR) indicating gas hydrates. From the GINCO I project there is evidence for the existence of two accretionary wedges along the Sunda Arc: wedge I is of assumed Paleogene age and wedge II of Neogene to Recent age. The first inner wedge I is composed of tectonic flakes which are correlated from SE Sumatra across the southern Sunda Strait to NW Java. This implies a very similar plate tectonic regime at the time of the flake development during the Upper Oligocene to Lower Miocene and without marked differences in plate convergence direction from Java to Sumatra. Wedge I shows backthrusting along the northern transition toward the fore-arc basin. Today, wedge I forms the outer arc high and the backstop for the younger, outer wedge II. Magnetic, gravity and seismic results show, that within both wedges, there are no indications for an oceanic crustal splinter as hitherto postulated. Both wedges are underlain by oceanic crust of the subducting Indo-Australian slab which could be correlated from the trench off Sumatra up to 135 km to the northeast and up to 65 km from the trench off Java. Since the top of the oceanic crust differs considerably in reflectivity and surface relief we distinguished two types in the seismic records. One type is characterized by strong top reflections and a smooth surface and underlies accretionary wedge II and the southwest part of the wedge I (outer arc high) off Sumatra and Java. The second type has a low reflectivity and a rougher relief and underlies the tectonic flakes of accretionary wedge I (outer arc high) between the southwestern tip of Sumatra, the SundaStrait and NW Java. The missing outer arc high off the southern entrance of the Sunda Strait is explained by Neogene transtension in combination with arc-parallel strike-slip movements. The NW-SE running, transpressional Mentawai strike-slip fault zone (MFZ) was correlated from the SE Sumatra fore-arc basin to the NW Java fore-arc basin. Off the Sunda Strait northward bending branches of the MFZ are connected with the Sumatra Fault zone (SFZ). It is speculated that the SFZ originally was attached to the Cimandiri-Pelabuhan-Ratu strike-slip faults and shifted from the volcanic arc position into the fore-arc basin area due to clockwise rotation of Sumatra with respect to Java as well as due to increasingly oblique plate convergence since the late Lower Miocene. We explain the transtension of the western Sunda Strait (Semangka graben) and the transpression with inversion of the eastern Sunda Strait, along the newly detected Krakatau Basin, by this rotation. Seismostratigraphic interpretation revealed 5 main sequences (A - E), tentatively dated as Paleogene to Recent in age. The oldest seismic sequence A of assumed Eocene to Oligocene age is bounded at the top by a major erosional unconformity that was identified on all GINCO seismic profiles. The seaward diverging seismic pattern of sequence A is interpreted as a correlative sequence to the prograding Paleogene deltaic sediments encountered by wells offshore central and northern Sumatra. This is opposed to previous interpretation which assumed seaward dipping reflector sequences of basaltic origin erupted along the former Mesozoic passive margin of Sumatra. According to constructed time structure maps, the main NW-SE running depocentres of the post-Paleogene sediments are arc-parallel off Sumatra and Java with thicknesses of 3 s (TWT) and 5 s (TWT), respectively. The main depocentres of the Semangka graben and of the Krakatau Basin of the Sunda Strait strike north-south and have infills of 2 s - 5 s (TWT). Bottom simulating reflectors (BSR) occur within the upper sequences C - D along the flanks of the fore-arc basins and along doming structures but could not be detected in basin centres. Empiric relations of heat flow values and depths of BSR were determined indicating that with increasing waterdepth and decreasing heat flow the depths of the BSR increase.

Citation proposal
. Processed seismic data of Cruise SO137 GINCO I 1998. https://gdk.gdi-de.org/geonetwork/srv/api/records/d84b85d7-1b1f-4d9d-8ec9-5e3aa2c6bdd3

Simple

Alternate title: SO137 GINCO I 1998

Date ( Creation ): 1998-12-28

Identifier: 5d32c875-b42b-2db2-9be4-44d2d9898d00

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 )

Indian Ocean
Sunda Arc
Sunda Strait
Indischer Ozean
Sundabogen
Sundastraße
Sumatra
Java

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: SO137 GINCO I 1998, (c) BGR, Hannover, 2019

Spatial representation type: Vector

Metadata language: English

Character set: UTF8

Topic category

Geoscientific information

Distribution format

Shapefile (n/a )

Transfer size: 2

OnLine resource: SO137 GINCO I 1998 (Shapefile)
SO137 GINCO I 1998 im Format ESRI Shape

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OnLine resource: Karte im BGR-Geoviewer
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Hierarchy level: Dataset

Conformance result

Date ( Publication ): 2010-12-08

Explanation: siehe dazu die angegebene Durchführungsbestimmung

Statement: During the period from 21st November to 28th December 1998 BGR acquired seismic lines off Sumatra and Java during cruise SO137 with RV SONNE. The lines SO137-24, SO137-35 and SO137-35C are raw data. The lines SO137-01, SO137-02, SO137-03, SO137-06, SO137-06A, SO137-07, SO137-09, SO137-09A, SO137-10, SO137-11, SO137-12, SO137-12A, SO137-14, SO137-14A, SO137-14B, SO137-19, SO137-20, SO137-21, SO137-22, SO137-23, SO137-25, SO137-26, SO137-27, SO137-28, SO137-29, SO137-30, SO137-31, SO137-32, SO137-33, SO137-34, SO137-34A, SO137-36, SO137-36A, SO137-37, SO137-38, SO137-38A, SO137-39, SO137-39A, SO137-40, SO137-41, SO137-42, SO137-42A and SO137-42B are migrated data.