Subduction dynamics, tectonics, and dynamic topography in the Banda-Java subduction zone

2021 ◽  
Author(s):  
Laurent Husson ◽  
Nicolas Riel ◽  
Sonny Aribowo ◽  
Christine Authemayou ◽  
Danny Hilman Natawidjaja ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Australian Plate ◽  
Banda Arc ◽  
Slab Rollback ◽  
Australian Continent ◽  
Slab Tearing ◽  
Back Arc ◽  
Dynamic Subsidence

<p>At the far end of the Tethyan realm, the Indo-Australian plate subducts in the Java and Banda trenches. Across the trench, a checkerboard-like distribution of continental and oceanic units sets the geodynamic stage since the Australian continent docked into the subduction zone a few Myr ago: to the East, the Australian continent now subducts and collides with the mostly oceanic Wallacea while to the West, the Indian oceanic plate subducts underneath continental Sundaland. We hypothesize that this fast and transient geodynamic regime explains many observations that characterize the region over the last few Myr: slab rollback and formation of the Banda arc, subsidence of the Weber superdeep seafloor to more than 7000 m, back-arc thrusting in Flores, dynamic subsidence in Sundaland and Sahul, and controversial slab tearing underneath Timor. We set out to model subduction dynamics accounting for the complex assemblage of plates in a real-Earth perspective, using the fast thermo-mechanical code LaMEM that allows dealing with complex setups. Our results predict the winding of the subduction zone around Papua, ultimately retreating into the Banda embayment, thereby causing the extreme dynamic subsidence of the Banda seafloor. Geometrical consistency imposes coeval slab tearing underneath Timor while the slab rolls back. The formation of the Flores backthrust quickly follows Australian collision with Wallacea and propagates westward in continental Sundaland. Shortening rates quickly drop tenfold while entering Sundaland, in Java, in agreement with kinematic and structural observations. In the geologically near future, the back-arc thrust is predicted to reverse the subduction polarity, Wallacea being on the brink to subduct southward underneath Australia. Last, transient mantle flow expectedly causes dynamic subsidence in Sahul and Sundaland, thereby profoundly remodeling the physiography of the entire region.</p>

Overriding plate deformation and topography during slab rollback and slab rollover: insights from subduction experiments

2021 ◽  
Author(s):  
Kai Xue ◽  
Wouter P. Schellart ◽  
Vincent Strak
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Large Scale ◽  
Dimensional Space ◽  
Viscous Drag ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Makran Subduction Zone ◽  
Plate Deformation ◽  
Slab Rollback

<p>Overriding plate deformation (OPD) and topography vary at different subduction zones, with some subduction zones showing mainly overriding plate extension and low topography (e.g. Mariana, Tonga, Izu-Bonin subduction zones), while some showing mainly shortening and elevated topography (e.g. Makran, southern Manila subduction zones). Here we investigate how different subduction modes, namely trench retreat and trench advance, affect OPD and generate corresponding topography with fully dynamic analogue models of time-evolving subduction in three-dimensional space. We conduct two sets of experiments, one of which is characterized by trench retreat and slab rollback, and the other characterized by trench advance and slab rollover. We compute the mantle flow, the overriding plate strain and topography during subduction using the particle image velocimetry technique (PIV). The overriding plate in the experiments showing continuous trench retreat experiences overall extension, while in the experiments with trench advance following trench retreat it experiences overall shortening. The overriding plate in both trench retreat and trench advance subduction modes present fore-arc shortening and intra-arc extension. Our experiments indicate that the overall OPD except in the fore-arc region is mainly driven by the horizontal mantle flow at the base of the OP inducing a viscous drag force (F<sub>D</sub>), and is determined by the gradient of the horizontal mantle flow velocity (dv<sub>x</sub>/dx). Furthermore, a large-scale trenchward overriding plate tilting and an overall subsidence of the overriding plate were observed in the experiments showing continuous trench retreat, while a landward tilting and an overall uplift of the overriding plate were observed during long-term trench advance. The two types of topography during the two different subduction modes can be ascribed to the large-scale trenchward and landward mantle flow, respectively, and thus represent forms of dynamic topography. Our models showing trench advance provide a possible mechanism for OPD in the Makran subduction zone, which has experienced overall trench-normal tectonic shortening in the overriding plate, but shows extension in a local region of the coastal Makran that is spatially comparable to that in our experiments.  In addition, these models might also provide an explanation for the regional topography at the Makran subduction zone, which shows a long-wavelength topographic high in the overriding plate near the trench that decreases northward.</p>

scholarly journals Early Results of P Wave Regional Tomography Study at Sunda-Banda Arc using BMKG Seismic Network

2021 ◽  
Vol 873 (1) ◽  
pp. 012065
Author(s):  
M S Haq ◽  
Haolia ◽  
M I Sulaiman ◽  
I Madrinovella ◽  
S Satiawan ◽  
...  
Keyword(s):  
Northern Region ◽  
P Wave ◽  
Eurasian Plate ◽  
Lower Velocity ◽  
Seismicity Pattern ◽  
Early Results ◽  
Australian Plate ◽  
Banda Arc ◽  
Australian Continent ◽  
Back Arc

Abstract The plate movement, geological structure, magmatism, and seismic activity in the area of Bali to East Nusa Tenggara are mainly related with the subducting of Indo-Australian Plate underneath the Eurasian plate. The complexity is added with the recent collision of Australian continent lithosphere with the western Banda arc, along the islands of Flores, Sumba and Timor island. Our study area is known as the Sunda-Banda arc transition. With the aim of imaging subsurface structure, we perform seismic tomography inversion using regional events. We collected 5 years of earthquake data (January 2015 – December 2019) from the Indonesian Agency of Meteorology, Climatology, and Geophysics (BMKG). The output of our data processing is not limited to only P wave velocity model, but also relocated seismicity pattern in the region. In general, seismicity pattern shows dominant shallow events in the south that progressively shift into deeper events in the north down to a few 500 km, marking a dipping subduction zone in this region. A group of shallow events down to a depth of 50 km is also seen at the norther region that may relate to back-arc thrust activity. P wave tomogram model show a lower velocity perturbation at a depth of 30 km that could be associated with magmatic activity along the volcanic front line. Higher P wave perturbation model are spotted at two different zones, the first one is marking a dipping Indo-Australian plate down to depth of 400 km. We noticed that the angle of dipping is steeper in the Eastern part compared to the Western part. The second a relatively flat at shallow depth at the northern region from the island of Lombok to Nusa Tenggara Timur that may mark the back-arc thrust region

scholarly journals A subduction influence on ocean ridge basalts outside the Pacific subduction shield

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
A. Y. Yang ◽  
C. H. Langmuir ◽  
Y. Cai ◽  
P. Michael ◽  
S. L. Goldstein ◽  
...  
Keyword(s):  
Upper Mantle ◽  
The Arctic ◽  
Mantle Flow ◽  
Mantle Heterogeneity ◽  
Gakkel Ridge ◽  
The Pacific ◽  
Mid Ocean Ridge ◽  
The Pacific Ocean ◽  
Back Arc ◽  
Ocean Ridge

AbstractThe plate tectonic cycle produces chemically distinct mid-ocean ridge basalts and arc volcanics, with the latter enriched in elements such as Ba, Rb, Th, Sr and Pb and depleted in Nb owing to the water-rich flux from the subducted slab. Basalts from back-arc basins, with intermediate compositions, show that such a slab flux can be transported behind the volcanic front of the arc and incorporated into mantle flow. Hence it is puzzling why melts of subduction-modified mantle have rarely been recognized in mid-ocean ridge basalts. Here we report the first mid-ocean ridge basalt samples with distinct arc signatures, akin to back-arc basin basalts, from the Arctic Gakkel Ridge. A new high precision dataset for 576 Gakkel samples suggests a pervasive subduction influence in this region. This influence can also be identified in Atlantic and Indian mid-ocean ridge basalts but is nearly absent in Pacific mid-ocean ridge basalts. Such a hemispheric-scale upper mantle heterogeneity reflects subduction modification of the asthenospheric mantle which is incorporated into mantle flow, and whose geographical distribution is controlled dominantly by a “subduction shield” that has surrounded the Pacific Ocean for 180 Myr. Simple modeling suggests that a slab flux equivalent to ~13% of the output at arcs is incorporated into the convecting upper mantle.

Age, chemistry, and tectonic setting of Miramichi terrane (Early Paleozoic) volcanic rocks, eastern and east-central Maine, USA

2021 ◽  
Vol 57 ◽  
pp. 239-273
Author(s):  
Allan Ludman ◽  
Christopher McFarlane ◽  
Amber T.H. Whittaker
Keyword(s):  
New Brunswick ◽  
Subduction Zone ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Calc Alkaline ◽  
East Central ◽  
Arc Volcanism ◽  
Middle Ordovician ◽  
Volcanic Suite ◽  
Back Arc

Volcanic rocks in the Miramichi inlier in Maine occur in two areas separated by the Bottle Lake plutonic complex: the Danforth segment (Stetson Mountain Formation) north of the complex and Greenfield segment to the south (Olamon Stream Formation). Both suites are dominantly pyroclastic, with abundant andesite, dacite, and rhyolite tuffs and subordinate lavas, breccias, and agglomerates. Rare basaltic tuffs and a small area of basaltic tuffs, agglomerates, and lavas are restricted to the Greenfield segment. U–Pb zircon geochronology dates Greenfield segment volcanism at ca. 469 Ma, the Floian–Dapingian boundary between the Lower and Middle Ordovician. Chemical analyses reveal a calc-alkaline suite erupted in a continental volcanic arc, either the Meductic or earliest Balmoral phase of Popelogan arc activity. The Maine Miramichi volcanic rocks are most likely correlative with the Meductic Group volcanic suite in west-central New Brunswick. Orogen-parallel lithologic and chemical variations from New Brunswick to east-central Maine may result from eruptions at different volcanic centers. The bimodal Poplar Mountain volcanic suite at the Maine–New Brunswick border is 10–20 myr younger than the Miramichi volcanic rocks and more likely an early phase of back-arc basin rifting than a late-stage Meductic phase event. Coeval calc-alkaline arc volcanism in the Miramichi, Weeksboro–Lunksoos Lake, and Munsungun Cambrian–Ordovician inliers in Maine is not consistent with tectonic models involving northwestward migration of arc volcanism. This >150 km span cannot be explained by a single east-facing subduction zone, suggesting more than one subduction zone/arc complex in the region.

Geochemical characteristics of basalts from Andaman subduction zone: Implications on magma genesis at intraoceanic back-arc spreading centres

2018 ◽  
Vol 54 (6) ◽  
pp. 3489-3508 ◽  
Author(s):  
Abhishek Saha ◽  
Abhay V. Mudholkar ◽  
K.A. Kamesh Raju ◽  
Bhagyashee Doley ◽  
Simontini Sensarma
Keyword(s):  
Subduction Zone ◽  
Geochemical Characteristics ◽  
Magma Genesis ◽  
Back Arc

scholarly journals The impact of rheological uncertainty on dynamic topography predictions

Solid Earth ◽  
2019 ◽  
Vol 10 (6) ◽  
pp. 2167-2178 ◽  
Author(s):  
Ömer F. Bodur ◽  
Patrice F. Rey
Keyword(s):  
Mantle Convection ◽  
Numerical Experiments ◽  
Mantle Flow ◽  
Dynamic Topography ◽  
Density Anomaly ◽  
Low Viscosity ◽  
Local Reduction ◽  
Dynamic Components ◽  
Mantle Rheology ◽  
The Impact

Abstract. Much effort is being made to extract the dynamic components of the Earth's topography driven by density heterogeneities in the mantle. Seismically mapped density anomalies have been used as an input into mantle convection models to predict the present-day mantle flow and stresses applied on the Earth's surface, resulting in dynamic topography. However, mantle convection models give dynamic topography amplitudes generally larger by a factor of ∼2, depending on the flow wavelength, compared to dynamic topography amplitudes obtained by removing the isostatically compensated topography from the Earth's topography. In this paper, we use 3-D numerical experiments to evaluate the extent to which the dynamic topography depends on mantle rheology. We calculate the amplitude of instantaneous dynamic topography induced by the motion of a small spherical density anomaly (∼100 km radius) embedded into the mantle. Our experiments show that, at relatively short wavelengths (<1000 km), the amplitude of dynamic topography, in the case of non-Newtonian mantle rheology, is reduced by a factor of ∼2 compared to isoviscous rheology. This is explained by the formation of a low-viscosity channel beneath the lithosphere and a decrease in thickness of the mechanical lithosphere due to induced local reduction in viscosity. The latter is often neglected in global mantle convection models. Although our results are strictly valid for flow wavelengths less than 1000 km, we note that in non-Newtonian rheology all wavelengths are coupled, and the dynamic topography at long wavelengths will be influenced.

Subduction-related magmatic imprint of most Philippine ophiolites: implications on the early geodynamic evolution of the Philippine archipelago

2004 ◽  
Vol 175 (5) ◽  
pp. 443-460 ◽  
Author(s):  
Rodolfo A. Tamayo* ◽  
René C. Maury* ◽  
Graciano P. Yumul ◽  
Mireille Polvé ◽  
Joseph Cotten ◽  
...  
Keyword(s):  
Partial Melting ◽  
Subduction Zone ◽  
Volcanic Rocks ◽  
The Philippines ◽  
Island Arc ◽  
Island Arcs ◽  
Geodynamic Evolution ◽  
Wide Range ◽  
Opening And Closing ◽  
Back Arc

Abstract The basement complexes of the Philippine archipelago include at least 20 ophiolites and ophiolitic complexes. These complexes are characterised by volcanic sequences displaying geochemical compositions similar to those observed in MORB, transitional MORB-island arc tholeiites and arc volcanic rocks originating from modern Pacific-type oceans, back-arc basins and island arcs. Ocean island basalt-like rocks are rarely encountered in the volcanic sequences. The gabbros from the ophiolites contain clinopyroxenes and plagioclases showing a wide range of XMg and An values, respectively. Some of these gabbros exhibit mineral chemistries suggesting their derivation from basaltic liquids formed from mantle sources that underwent either high degrees of partial melting or several partial melting episodes. Moreover, some of the gabbros display a crystallization sequence where orthopyroxene and clinopyroxene appeared before plagioclase. The major element compositions of coexisting orthopyroxenes and olivines from the mantle peridotites are consistent with low to high degrees of partial melting. Accessory spinels in these peridotites display a wide range of XCr values as well with some of them above the empirical upper limit of 0.6 often observed in most modern mid-oceanic ridge (MOR) mantle rocks. Co-existing olivines and spinels from the peridotites also exhibit compositions suggesting that they lastly equilibrated under oxidizing mantle conditions. The juxtaposition of volcanic rocks showing affinities with modern MOR and island arc environments suggests that most of the volcanic sequences in Philippine ophiolites formed in subduction-related geodynamic settings. Similarly, their associated gabbros and peridotites display mineralogical characteristics and mineral chemistries consistent with their derivation from modern supra-subduction zone-like environments. Alternatively, these rocks could have, in part, evolved in a supra-subduction zone even though they originated from a MOR-like setting. A simplified scenario regarding the early geodynamic evolution of the Philippines is proposed on the basis of the geochemical signatures of the ophiolites, their ages of formation and the ages and origins of the oceanic basins actually bounding the archipelago, including basins presumed to be now totally consumed. This scenario envisages the early development of the archipelago to be largely dominated by the opening and closing of oceanic basins. Fragments of these basins provided the substratum on top of which the Cretaceous to Recent volcanic arcs of the Philippines were emplaced.

scholarly journals The two-stage Aegean extension, from localized to distributed, a result of slab rollback acceleration

2016 ◽  
Vol 53 (11) ◽  
pp. 1142-1157 ◽  
Author(s):  
Jean-Pierre Brun ◽  
Claudio Faccenna ◽  
Frédéric Gueydan ◽  
Dimitrios Sokoutis ◽  
Mélody Philippon ◽  
...  
Keyword(s):  
Middle Miocene ◽  
Middle Eocene ◽  
Sedimentary Basins ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Western Anatolia ◽  
Two Stage ◽  
The North ◽  
Slab Rollback ◽  
Slab Tearing

Back-arc extension in the Aegean, which was driven by slab rollback since 45 Ma, is described here for the first time in two stages. From Middle Eocene to Middle Miocene, deformation was localized leading to (i) the exhumation of high-pressure metamorphic rocks to crustal depths, (ii) the exhumation of high-temperature metamorphic rocks in core complexes, and (iii) the deposition of sedimentary basins. Since Middle Miocene, extension distributed over the whole Aegean domain controlled the deposition of onshore and offshore Neogene sedimentary basins. We reconstructed this two-stage evolution in 3D and four steps at Aegean scale by using available ages of metamorphic and sedimentary processes, geometry, and kinematics of ductile deformation, paleomagnetic data, and available tomographic models. The restoration model shows that the rate of trench retreat was around 0.6 cm/year during the first 30 My and then accelerated up to 3.2 cm/year during the last 15 My. The sharp transition observed in the mode of extension, localized versus distributed, in Middle Miocene correlates with the acceleration of trench retreat and is likely a consequence of the Hellenic slab tearing documented by mantle tomography. The development of large dextral northeast–southwest strike-slip faults, since Middle Miocene, is illustrated by the 450 km long fault zone, offshore from Myrthes to Ikaria and onshore from Izmir to Balikeshir, in Western Anatolia. Therefore, the interaction between the Hellenic trench retreat and the westward displacement of Anatolia started in Middle Miocene, almost 10 Ma before the propagation of the North Anatolian Fault in the North Aegean.

The Australian Plate and underlying mantle from waveform tomography with massive datasets

2021 ◽  
Author(s):  
Janneke de Laat ◽  
Sergei Lebedev ◽  
Bruna Chagas de Melo ◽  
Nicolas Celli ◽  
Raffaele Bonadio
Keyword(s):  
Structural Information ◽  
Azimuthal Anisotropy ◽  
P Wave ◽  
Depth Range ◽  
S Wave ◽  
Crust And Upper Mantle ◽  
Southern Boundary ◽  
Velocity Anomaly ◽  
Australian Plate ◽  
Australian Continent

&lt;p&gt;We present a new S-wave velocity tomographic model of the Australian Plate, Aus21.&amp;#160; It is constrained by waveforms of 0.9 million seismograms with both the corresponding sources and stations located within the half-hemisphere centred at the Australian continent. Waveform inversion extracts structural information from surface, S- and multiple S-waves on the seismograms in the form of a set of linear equations. These equations are then combined in a large linear system and inverted jointly to obtain a tomographic model of S- and P-wave speeds and S-wave azimuthal anisotropy of the crust and upper mantle. The model has been validated by resolution tests and, for particular locations in Australia with notable differences with previous models, by independent inter-station measurements of surface-wave phase velocities, which we performed using available array data.&amp;#160;&lt;/p&gt;&lt;p&gt;&amp;#160;&lt;/p&gt;&lt;p&gt;Aus21 offers new insights into the structure and evolution of the Australian Plate and its boundaries. The Australian cratonic lithosphere occupies nearly all of the western and central Australia but shows substantial lateral heterogeneity. It extends up to the northern edge of the plate, where it is colliding with island arcs, without subducting. The rugged eastern boundary of the cratonic lithosphere provides a lithospheric definition of the Tasman Line. The thin, warm lithosphere below the eastern part of the continent, east of the Tasman Line, underlies the Cenozoic volcanism locations in the area. The lithosphere is also thin and warm below much of the Tasman Sea, underlying the Lord Howe hotspot and the submerged part of western Zealandia. A low velocity anomaly that may indicate the single source of the Lord Howe and Tasmanid hotspots is observed in the transition zone offshore the Australian continent, possibly also sourcing the East Australia hotspot. Another potential hotspot source is identified below the Kermadec Trench, causing an apparent slab gap in the overlying slab and possibly related to the Samoa Hotspot to the north. Below a portion of the South East Indian Ridge (the southern boundary of the Australian Plate) a pronounced high velocity anomaly is present in the 200-400 km depth range just east of the Australian-Antarctic Discordance (AAD), probably linked to the evolution of this chaotic ridge system.&lt;/p&gt;

scholarly journals Ophiolitic Pyroxenites Record Boninite Percolation in Subduction Zone Mantle

Minerals ◽  
2019 ◽  
Vol 9 (9) ◽  
pp. 565 ◽  
Author(s):  
Véronique Le Roux ◽  
Yan Liang
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Mantle Wedge ◽  
Major Element ◽  
Early Stage ◽  
Diffusion Modeling ◽  
Melt Infiltration ◽  
Melt Percolation ◽  
Back Arc ◽  
Parental Melts

The peridotite section of supra-subduction zone ophiolites is often crosscut by pyroxenite veins, reflecting the variety of melts that percolate through the mantle wedge, react, and eventually crystallize in the shallow lithospheric mantle. Understanding the nature of parental melts and the timing of formation of these pyroxenites provides unique constraints on melt infiltration processes that may occur in active subduction zones. This study deciphers the processes of orthopyroxenite and clinopyroxenite formation in the Josephine ophiolite (USA), using new trace and major element analyses of pyroxenite minerals, closure temperatures, elemental profiles, diffusion modeling, and equilibrium melt calculations. We show that multiple melt percolation events are required to explain the variable chemistry of peridotite-hosted pyroxenite veins, consistent with previous observations in the xenolith record. We argue that the Josephine ophiolite evolved in conditions intermediate between back-arc and sub-arc. Clinopyroxenites formed at an early stage of ophiolite formation from percolation of high-Ca boninites. Several million years later, and shortly before exhumation, orthopyroxenites formed through remelting of the Josephine harzburgites through percolation of ultra-depleted low-Ca boninites. Thus, we support the hypothesis that multiple types of boninites can be created at different stages of arc formation and that ophiolitic pyroxenites uniquely record the timing of boninite percolation in subduction zone mantle.

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