Within the framework of the research project SINDBAD (Seismic and Geoacoustic Investigations Along the Sunda-Banda Arc Transition) marine geophysical investigations have been carried out with RV SONNE from October 9th, 2006, to November 9th, 2006, off the eastern Sunda Arc and at the transition to the Banda Arc in Indonesia. The research cruise SO190 Leg 1 started in Jakarta, Indonesia and ended in Darwin, Australia. During this cruise, multichannel seismics (MCS), magnetics (M), and gravimetry (G) measurements have been carried out. Simultaneously, SIMRAD (multibeam echosounder) and PARASOUND (sediment echosounder) data have been collected using RV SONNEs onboard systems. During the expedition, a total of 4,933 km of profiles with MCS, M, and G have been acquired. Six of the 20 profiles are long overview profiles perpendicular to the deformation front and cover the entire forearc from the forearc basin across the outer arc high, the deformation front onto the oceanic lithosphere. Additional profiles have been acquired along strike in the Lombok forearc basin and in the Savu Basin. The main goal of the project SINDBAD is to investigate the relation between the variability of the lower plate and the tectonic evolution of the overriding plate (formation of an outer arc high, development of forearc basins, and accretion and erosion processes of the overriding plate). The "raw materials" – seafloor sediments, oceanic crust (at the Banda Arc also continental crust) and mantle lithosphere – are carried into the subduction system at the trench. The influence of these "raw materials" on the overriding plate is controlled by a number of factors: e.g. the convergence rate, the obliqueness of convergence and the physical and chemical properties of the lower plate (e.g. its age, its sediment-cover and –thickness, its fluid content and the composition of the crust). Forearc basins are today attracting increased attention because of their hydrocarbon potential. The forearc basins of the eastern Sunda Arc are still frontier areas which are almost unexplored. An additional goal of this project is therefore the assessment of the hydrocarbon potential of the Lombok Basin. In contrast to the Sumatra subduction zone, only a small amount of pelagic sediment is carried into the subduction system offshore East Java, Bali, Lombok, Sumbawa and Sumba. This results e.g. in a less pronounced development of the outer arc high, which is subaerial off Sumatra, but entirely below the sea surface in the eastern Sunda Arc. The Roo Rise, which is subducting off East Java, is a morphological high that lies about 1500 m higher than the Argo Abyssal Plain which is subducting further to the east. Despite of these pronounced differences, the deformation front in both areas shows similarities. While the foot of the slope shows lower dip than the upper slope, both areas are characterized by landward dipping thrust sheets. In both areas the outer arc high is characterized by active faults (the recent activity is indicated by deformed basin sediments on the outer arc high) and therefore no indications for a static backstop have been found. The accretionary character of the deformation front is clearly indicated in both areas, while subrosion in association with the subsidence of the Lombok Basin can not be excluded based on the preliminary interpretations. The trench in both areas is devoid of sediments, which indicates erosional processes caused by currents along the trench strike. However, a depocenter for these sediments could not be localized yet. While a forearc basin is not clearly developed off East Java, the Lombok forearc basin with water depths of more than 4000 m extends from off Bali to off Sumbawa. On the southern slope of the basin prograding sedimentary sequences indicate uplift, probably caused by the subducting Roo Rise or a growth of the outer arc high. Additionally, carbonate platforms on the acoustic basement indicate phases of rapid subsidence of the basin. The sediment thickness reaches a total of about 3.5 sec TWT. A few seismic "bright spots", but no bottom simulating reflectors (BSRs) have been identified in the basin. The profiles striking along the basin axis indicate paleo-depocenters in the western part of the profile, while the recent depocenter is located in the eastern part of the basin. On the northern flank of the Lombok basin, indications for submarine volcanism (recent activity is unknown) are indicated by a seamount reaching above the seafloor associated with a clear magnetic anomaly. East of the Lombok Basin the island of Sumba is located, which is regarded as a microcontinent that has been attached to the island arc during the Late Oligocene. Sumbas geographical location in front of the island arc is usually characterized by the location of a forearc basin and correlates with the seaward displacement of the deformation front (Roti Basin) at the transition from ocean/island arc subduction of the Sunda Arc to continent/island arc collision of the Banda Arc. An uplift of about 0.5 cm/a is reported for Sumba, associated with the underplating of the continental Scott Plateau. The uplift is especially evident in the MCS data. To the east of the Lombok Basin depocenter, a transition zone with deep reaching faults is observed, associated with eastward dipping sedimentary and basement structures. This transition zone is also indicated by anomalies in the magnetic and gravity data, the latter indicating isostatic undercompensation. On the western flank of Sumba, deformed sedimentary sequences indicate gravitational gliding in association with the uplift of Sumba. East of Sumba, two profiles into the Savu Basin have been acquired. Here the uplift of Sumba is indicated by the erosion of sedimentary sequences which have been deposited in the basin followed by uplift and subsequent erosion. Further indications of "inversion structures" are given by a reactivated thrust fault that in the past has served as the southern boundary of the Savu Basin und indicates recent activity by associated deformed basin sediments. The oceanic crust of the Argo Abyssal Plain and the Roo Rise is characterized by thin sediments. On a connection profile between two long profiles on the Argo Abyssal Plain a basin with about 1.4 sec TWT of sediment has been observed, that, indicated by a magnetic anomaly, can be correlated with an age jump of about 15 Ma, thereby indicating a paleo plate boundary.
The northwestern Australian continental margin can be considered as a passive continental margin of the rifted atlantic type (Whitworth 1969; Powell 1973, 1976; Falvey 1974; Veevers 1974; Willcox 1974, 1976; Exon et al. 1975) which are usually associated with heavy accumulation of sediments (Beck et al. 1974) and are therefore of interest for hydrocarbon exploration in the longer term. The Federal Institute for Geosciences and Natural Resources (BGR, Hannover, Germany) has conducted geoscientific surveys at various continental margins of the Atlantic Ocean in the past years (Seibold 1972; Hinz et al. 1973; Seibold, Hinz 1974/1976; Seibold et al. 1975; Roeser et al. 1971) and the marine research programme of the Bureau of Mineral Resources, Geology & Geophysics (BMR, Canberra, Australia) is putting the focal point as well on the survey of the continental margins. Hence in the frame of the Australian-German contract of scientific and technical cooperation, BGR has proposed joint geoscientific surveys of the continental margins with the German research vessel VALDIVIA. The Scott-Plateau (NW-Australia) has been chosen as investigation area because BMR has carried out geophysical overview measurements previously in that region. The survey has been planned with the main focus on the geological processes at the early rift stadium and the set of problems about the "transition of oceanic to continental crust". The following regional geological units are known: the archaic-proterozoic Kimberley shield is followed by the Browse Basin - a NE striking epicontinental basin filled with mesozoic and tertiary sediments showing a thickness of up to 10 km (Powell 1976). It is presumed that the Browse Basin is delimitated by the Scott Plateau. Presumably, the Scott Plateau consists of continental crust which thins out to the north in direction to the Argo Abyssal Plain. The development of the Browse Basin is ascribed to a series of rift processes in the late paleozoic and triassic age where gas condensates have been detected at the drill hole Scott Reef 1. The contemporary configuration of the NW-Australian basins and the NW-Australian continental margin has been formed by an important middle jurassic rift phase and a subsequent drift phase. The cruises VA16-2A from 6th to the 25th of February 1977 with geophysical measurements and VA16-2B from 25th of February to 9th of March 1977 with geological sample recovery should clarify these processes. The working area of cruise VA16-2C from 11th to 23rd of March 1977 has been the Timor Trough and the Savu Sea which separate the islands Timor, Roti, Savu and Sumba from the volcanic islands of the inner Banda island arc. The crustal structure of Sumba, of the Savu Sea and of the inner Banda island arc near Flores should be investigated with seismic methods (small explosive charges fired from the research vessel VALDIVIA in the Savu Sea and intended recording units of the Flinders University on the islands Savu, Sumba and Flores) as well as with sonobuoy stations of BGR. Newer investigations (Audley Charles 1975, Chamalaun 1974) suggest that the islands of the Banda island arc (Sumba, Savu, Roti, Timor etc.) represent the northern border of the Australian continent being underlain by the crust of the Australian continent as opposed to the assumption of other investigators (e.g. Beck and Lehner 1974) who presume the northern border of the Australian continent at the Timor Trough south of the Timor island and postulate a subduction zone between the outer Banda island arc and Australia. BMR has provided 9 tons of explosives (Nitramon) with accessories for refraction seismics. The Flinders University has prepared 7 on-shore recording units and sent to Indonesia together with operating staff. BGR conducted the marine seismic work with explosive charges and off-shore recordings with sonobuoys for refraction seismic as well as reflection seismic, gravimetric and magnetic measurements.
Das Projekt "Teilprojekt 2: Konnektivität von Korallenriffen" wird vom Umweltbundesamt gefördert und von Universität Bremen, Zentrum für Umweltforschung und nachhaltige Technologien (UFT) durchgeführt. Die Aufgabenstellung für diesen Teil des Verbundprojektes besteht darin, für einige ausgewählte Riff-Organismen in der Region Spermonde und in der Savu-Sea eine Bestandsaufnahme im Hinblick auf ihre Diversität und ihre Populationsstrukturen und gleichzeitig eine Analyse ihrer Veränderungen in Abhängigkeit von ihrer Nutzung durch den Menschen (Fischerei) und die aktuellen Folgeschäden für die Umwelt anzufertigen. Dabei geht es nicht (mehr) um Fragen der grundlegenden Modellbildung dieser Zusammenhänge, sondern um die beispielhafte Untersuchung konkreter aktueller Fälle, bei denen die als Lebensgrundlage der dortigen Menschen wichtigen und dementsprechend kommerziell interessanten Arten oder solche, die aus ökologischen Gründen von besonderer Bedeutung sind, gefährdet sind. Aus den geplanten genetischen Analysen wird ersichtlich werden, in welchem Maße ihr aktueller Bestand oder sogar ihre Bestandserholung gefährdet ist und welche Seegebiete für ihren Schutz von besonderer Bedeutung sind. Gemeinsam mit Dr. Agus Nuryanto, Universität Jenderal Soedierman, und den Mitarbeitern der anderen Teilprojekte werden von Dr. J. Timm, UniHB, und Prof. M. Kochzius, FU Brüssel, in den indonesischen Regionen Gewebeproben der Organismen gesammelt und in Bremen im Labor analysiert. Die Analyse besteht in der Extraktion der DNA, der Auswahl der geeigneten genetischen Marker, der Amplifikation und Sequenzierung entsprechender DNA-Abschnitte, der bioinformatischen Datenanalyse und der Datenbereitstellung für die gemeinsame Ergebnisinterpretation mit den Projektpartnern.
Das Projekt "Leitantrag; Teilprojekt 1: Korallenriffe und Umwelteinflüsse, Teilprojekt 3: Korallenriffresilienz, Teilprojekt 4: Modellierung von Riffdynamiken, Teilprojekt 5: Capacity Building" wird vom Umweltbundesamt gefördert und von Leibniz-Zentrum für Marine Tropenökologie (ZMT) GmbH durchgeführt. Das Verbundprojekt verfolgt einem holistischen und interdisziplinären Untersuchungsansatz der Dynamiken in Korallenriffen unter einer großen Variabilität von Umweltbedingungen und Szenarien menschlicher Nutzung und Einwirkung. Der Fokus des Verbundes liegt auf vier Hauptzielen: a) Herausstellen der ökologischen Schlüsselprozesse und Hauptumweltfaktoren in Bezug auf lokale Rifffunktionen und Resilienz, b) Identifikation der wesentlichen treibenden Kräfte in den riffbasierten sozial-ökologischen Systemen, c) Etablierung von Werkzeugen für die Analyse von Korallenriffdynamiken und das Management von Korallenriffen d) Stärken der menschlichen und institutionellen Kapazitäten zur Begegnung mit Gefährdungen im Bereich von Küstenökosystemen und Unterstützung der sozial-ökologischen Resilienz in diesen Bereichen. Unsere Forschungsregionen (Spermonde Archipel, Savu Sea) wurden gemeinsam durch die indonesischen und deutschen Partner ausgewählt. Die spezifischen Untersuchungsflächen werden während der ersten Projektphase entsprechend der festgelegten Kriterien bestimmt. Der Verbund zielt auf die Analyse von resilienzbestimmenden Faktoren, mögliche Bedingungen für Phasenverschiebungen in Korallenriffen und die langfristige Entwicklungen im sozial-ökologischen Bereich in Verbindung mit unterschiedlichen Managementstrategien im Kontext von Veränderungen im Umweltbereich und des sozialen Wandels. Die indonesischen und deutschen Partner werden eng kooperieren um die Verbundziele zu erreichen.