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1

Online Resource

Sunda-Banda arc transition : incipient continent-island arc collision (northwest Australia) (2009)

Shulgin, A.

Associated volumes

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In: Geophysical research letters, Hoboken, NJ : Wiley, 1974, 36(2009), 1944-8007

In: volume:36

In: year:2009

In: extent:6

Description / Table of Contents: The eastern Sunda arc represents one of the few regions globally where the early stages of continent-arc collision can be studied. We studied along the western limit of the collision zone at the Sunda-Banda arc transition, where the Australian margin collides with the Banda island arc, causing widespread back arc thrusting. We present integrated results of a refraction/wide-angle reflection tomography, gravity modeling, and multichannel reflection seismic imaging using data acquired in 2006 southeast of Sumba Island. The composite structural model reveals the previously unresolved deep geometry of the collision zone. Changes in crustal structure encompass the 10-12 km thick Australian basement in the south and the 22-24 km thick Sumba ridge in the north, where backthrusting of the 130 km wide accretionary prism is documented. The structural diversity along this transect could be characteristic of young collisional systems at the transition from oceanic subduction to continent-arc collision.

Type of Medium: Online Resource

Pages: 6 , graph. Darst

ISSN: 1944-8007

DOI: 10.1029/2009GL037533

Language: English

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GEOMAR CATALOGUE

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2

Electronic Resource

Seismic Shear Waves in Deep Seismic Reflection Surveys: Some Notes on Problems and Profits (1999)

Lüschen, E.

Springer

Pure and applied geophysics 156 (1999), S. 83-95

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ISSN: 1420-9136

Keywords: Key words: Seismic profiles, S waves, anisotropy, three-component seismographs.

Source: Springer Online Journal Archives 1860-2000

Topics: Geosciences , Physics

Notes: Abstract —Shear (S) waves differ from compressional (P) waves because of their lower propagation velocities, their lower frequencies and due to the different character of their particle motion. The move-out of travel-time branches of S-wave reflections is different from P waves owing to the difference in the propagation velocities. To distinguish between P and S waves requires broadband-frequency acquisition, long receiver arrays and three-component recording. S-wave generation at the source and P-to-S-wave conversion at crustal interfaces can be very efficient, implying that there is a real danger of misinterpreting signals if only vertical components are used. On the other hand, integrated P- and S-wave studies promise to provide very efficient lithological discriminators in the crystalline crust, in particular concerning the quartz content, and indicators for rock anisotropy, which can be interpreted for the existence of fine layering, the direction of the recent stress regime (alignments of micro-fractures) or for the direction of palaeo-stress (alignments of minerals).

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/s000240050290

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3

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A seismic reflection-refraction experiment across the exposed lower crust in Calabria (southern Italy): first results (1992)

Lüschen, E. ; Nicolich, R. ; Cernobori, L. ; [et al.]

Oxford, UK : Blackwell Publishing Ltd

Terra nova 4 (1992), S. 0

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ISSN: 1365-3121

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Geosciences

Notes: Exposed crystalline basement of the Serre Mountains in Calabria presents a tilted block of a nearly complete section of the Hercynian continental lower crust (HCLC). In addition to petrological and structural data from surface mapping, and petrophysical data from the laboratory, a seismic reflection-refraction experiment was conducted in May 1990. This consisted of a 40 km long N-S profile crossing the HCLC and of four short transverse profiles, each recorded using 3-component receivers with an 80 m spacing and explosive sources.The reflectivity of the outcropping lower crustal units is lower than theoretically predicted from the observed compositional layering. A low-velocity zone, outcropping in the north, and dipping to the south, marks the contact between the HCLC and the underlying Alpine metamorphic units. Below this zone, the deeper crust appears well-structured by strong and continuous, discrete reflections down to 6.5–8 s t.w.t. (presumably the crust-mantle boundary at 19–24 km depth) with a dominant dip toward the south.Analysis of refracted-wave velocities reveals values systematically lower by up to 30% than laboratory data on rock samples or calculated data from modal analysis. This discrepancy can only partly be explained by the effect of microcracks (10%), the underestimation of the amount of leucosomes (2–5%) and the effect of seismic anisotropy (0–5%). The remaining discrepancy must be attributed to large scale alteration of the rocks due to Apennine tectogenetic events.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1365-3121.1992.tb00452.x

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DAVIS GATE: Geodynamik zwischen Grönland und Kanada Erste Ergebnisse der FS Maria S. Merian Expedition MSM09/3 (2008) (2009)

Gohl, Karsten ; Schreckenberger, B. ; Funck, D. ; [et al.]

In: EPIC3AK Geologie und Geophysik der Polargebiete in dewr DGP, Potsdam.-25. April 2009., 24

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Publication Date: 2019-07-17

Description: Während des Merian-Fahrtabschnitts MSM09/3 wurden Ende 2008 in einer Kooperation zwischen dem Alfred-Wegener-Institut für Polar- und Meeresforschung (AWI), der Bundesanstalt für Geowissenschaften und Rohstoffe (BGR), dem Geologischen Dienst von Dänemark und Grönland (GEUS) und der Dalhousie University geophysikalische Untersuchungen in der Baffinbucht und Davisstraße zwischen Grönland und dem kanadischen Baffininsel durchgeführt. Als Teilvorhaben des IPY-2007/08-Kernprojekts Plate Tectonics and Polar Gateways in the Earth System (PLATES & GATES) hat das Projekt DAVIS GATE das Ziel, eine tektonische und sedimentäre Rekonstruktion des Öffnungsprozesses dieser Meeresstraße zu entwickeln. Die Baffinbucht und Davisstraße spielen eine wichtige Rolle für den Flachwasseraustausch zwischen dem arktischen und dem atlantischen Ozean. Die plattentektonische Entwicklung sowie die magmatischen Ereignisse im Laufe dieser Entwicklung sind bisher kaum bekannt und erforderten eine eindringliche geophysikalische Untersuchung, um akkurate paläobathymetrische und paläogeographische Datensätze für eine vollständige geodynamische Rekonstruktion dieses Gateway zu erstellen. Entlang von drei refraktions/weitwinkelseismischen Profilen unter Nutzung von Ozeanbodenseismometern auf insgesamt 62 Stationen sowie dem Einsatz der Mehrkanal-Reflexionsseismik mit einem 3000 m langen Streamer sind Daten von der sedimentären Bedeckung bis in die tiefe Kruste und teilweise vom obersten Mantel gewonnen worden. Weitere seismische Profildaten ergänzen diese Messungen und lassen Einblicke in die Strukturen des Grundgebirges sowie der dominanten Verwerfungszonen, z.B. der Ungava-Störung, zu. Eine parallel angelegte Magnetfeldvermessung ist auf die Auflösung der zeitlichen Entwicklung der ozeanischen Kruste der Baffinbucht ausgerichtet worden. Ausdünnung und Absenkung der kontinentalen Kruste und Übergangskruste in der Davisstraße und die Entwicklung der ozeanischen Kruste der Baffinbucht konnten mit diesen geophysikalischen Daten, zu der auch kontinuierlich aufgezeichnete Schwerefeld- und Sedimentechographiedaten gehören, untersucht werden. Diese Daten liefern die Informationen über die geometrischen und physikalischen Eigenschaften der Kruste und ihrer Sedimentbedeckung, die für ein realistisches tektonisches, geodynamisches und sedimentäres Modell notwendig sind, das den kontinentalen Abbruchs und der Entwicklung des Ozeanbeckens zwischen Grönland und Kanada paläo-topographisch im Detail beschreibt.

Repository Name: EPIC Alfred Wegener Institut

Type: Conference , notRev

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Lower plate structure and upper plate deformational segmentation at the Sunda-Banda arc transition, Indonesia (2010)

Planert, Lars ; Kopp, Heidrun ; Lueschen, E. ; [et al.]

AGU (American Geophysical Union)

In: Journal of Geophysical Research: Oceans, 115 (B8). B08107.

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Publication Date: 2018-02-27

Description: The Sunda‐Banda arc transition at the eastern termination of the Sunda margin (Indonesia) represents a unique natural laboratory to study the effects of lower plate variability on upper plate deformational segmentation. Neighboring margin segments display a high degree of structural diversity of the incoming plate (transition from an oceanic to a continental lower plate, presence/absence of an oceanic plateau, variability of subducting seafloor morphology) as well as a wide range of corresponding fore‐arc structures, including a large sedimentary basin and an accretionary prism/outer arc high of variable size and shape. Here, we present results of a combined analysis of seismic wide‐angle refraction, multichannel streamer and gravity data recorded in two trench normal corridors located offshore the islands of Lombok (116°E) and Sumba (119°E). On the incoming plate, the results reveal a 8.6–9.0 km thick oceanic crust, which is progressively faulted and altered when approaching the trench, where upper mantle velocities are reduced to ∼7.5 km/s. The outer arc high, located between the trench and the fore‐arc basin, is characterized by sedimentary‐type velocities (Vp 〈 5.5 km/s) down to the top of the subducting slab (∼13 km depth). The oceanic slab can be traced over 70–100 km distance beneath the fore arc. A shallow serpentinized mantle wedge at ∼16 km depth offshore Lombok is absent offshore Sumba, where our models reveal the transition to the collisional regime farther to the east and to the Sumba block in the north. Our results allow a detailed view into the complex structure of both the deeper and shallower portions of the eastern Sunda margin.

Type: Article , PeerReviewed

Format: text

DOI: 10.1029/2009JB006713

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OceanRep: Article in a Scientific Journal - peer-reviewed

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Structure, evolution and tectonic activity of the eastern Sunda forearc, Indonesia, from marine seismic investigations (2011)

Lüschen, E. ; Müller, C. ; Kopp, Heidrun ; [et al.]

Elsevier

In: Tectonophysics, 508 (1-4). pp. 6-21. Date online first: 2011

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Publication Date: 2019-09-23

Description: Forearc structures of the eastern Sunda Arc are studied by new multichannel reflection seismic profiling. We image a high along-strike variability of the subducting oceanic plate, the interface between subducting and overriding plate, the accretionary wedge, the outer arc high and forearc basins. We highlight ongoing tectonic activity of the entire outer arc high: active out-of-sequence thrust faults connecting the plate interface with the seafloor, slope basins showing tilted sedimentary sequences on the outer arc high, vertical displacement of young seafloor sediments, and tilted sedimentary sequences in the Lombok forearc basin. While frontal accretion plays a minor role, the growth of the outer arc high is mainly attributed to oceanic sediments and crustal fragments, which are attached to the base of the upper plate and recycled within the forearc. We image ongoing large-scale duplex formation of the oceanic crust. The incoming oceanic crust is dissected by normal faulting into 5–10 km wide blocks within a 50–70 km wide belt seaward of the deep sea trench. These blocks determine the geometry and evolution of duplexes attached to the base of the overriding plate landward of the trench. Long-lasting and ongoing subsidence of the Lombok Basin is documented by distinct seismic sequences. In the Lombok Basin we image mud diapirs, fed from deeply buried sediments which may have been mobilized by rising fluids. We propose a wrench fault system in the eastern Lombok forearc basin that decouples the subduction regime of the Sunda Arc from the continent–island arc collision regime of the western Banda Arc. The observed tectonic activity of the entire forearc system reflects a high earthquake and tsunami hazard, similar to the western part of the Sunda Arc.

Type: Article , PeerReviewed

Format: text

DOI: 10.1016/j.tecto.2010.06.008

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