Seismic Structure and Tectonic Evolution of Borneo and Sulawesi

2020 ◽  
Author(s):  
Harry Telajan Linang ◽  
Amy Gilligan ◽  
Jennifer Jenkins ◽  
Tim Greenfield ◽  
Nick Rawlinson
Keyword(s):  
Subduction Zones ◽  
Receiver Function ◽  
Leading Edge ◽  
Crustal Thickness ◽  
The Philippines ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Surface Mapping ◽  
Indonesian Archipelago ◽  
Subduction Setting

<p>Southeast Asia (SEA) is one of the most active tectonic regions on the planet due to its convergent setting, which accommodates rapid northward motion of the Indo-Australian plate and westward motion of the Philippines Sea plate. This activity gives rise to intense seismicity along the convergent plate margins in and around SEA, including the Sunda Arc, which wraps its way around the southern margin of the Indonesian archipelago.</p><p>Borneo is located at the centre of SEA, on the leading edge of the Sundaland block of the Eurasian plate, and exhibits lower rates of seismicity when compared to the surrounding regions due to its intraplate setting. Sulawesi, an island which lies adjacent to Borneo in the east, is characterised by intense seismicity due to multiple subduction zones in its vicinity. The tectonic relationship between the two islands is poorly understood, as is the provenance of their lithosphere, which may have Eurasian or East Gondwana origin.</p><p>The aim of this presentation is to showcase recent receiver function results from temporary and permanent broadband seismic stations in the region, which can be used to help improve our understanding of the structure of the crust and the mantle lithosphere beneath Borneo and Sulawesi. H-K stacking, receiver function migration and inversion are all applied in an effort to determine robust crustal thickness estimates and variations in shear wavespeed with depth. Our preliminary results from Borneo indicate that the crust beneath Sabah (northern Borneo), which is a post-subduction setting, appears to be much more complex than the rest of the island. Furthermore, we find that crustal thickness varies between different tectonic blocks defined from surface mapping, with the thinnest crust (24 km thick) occurring beneath Sarawak in the northwest.</p>

Seismic Structure and Tectonic Evolution of Borneo and Sulawesi

2021 ◽  
Author(s):  
Harry Telajan Linang ◽  
Amy Gilligan ◽  
Jennifer Jenkins ◽  
Tim Greenfield ◽  
Felix Tongkul ◽  
...  
Keyword(s):  
Subduction Zones ◽  
Receiver Function ◽  
Leading Edge ◽  
Sedimentary Basins ◽  
Crustal Thickness ◽  
The Philippines ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Seismic Stations ◽  
Preliminary Results

<div> <div> <div> <p>Borneo is located at the centre of Southeast Asia, which is one of the most active tectonic regions on Earth due to the subduction of the Indo-Australian plate in the south and the Philippines Sea plate in the east. Borneo resides on the leading edge of the Sundaland block of the Eurasian plate and exhibits lower rates of seismicity when compared to the surrounding regions due to its intraplate setting. Sulawesi, an island which lies just southeast of Borneo, is characterised by intense seismicity due to multiple subduction zones in its vicinity. The tectonic relationship between the two islands is poorly understood, including the provenance of their respective lithospheres, which may have Eurasian and/or East Gondwana origin.</p> <p>Here, we present recent receiver function (RF) results from temporary and permanent broadband seismic stations in the region, which can be used to help improve our understanding of the crust and mantle lithosphere beneath Borneo and Sulawesi. We applied H-K stacking, receiver function migration and inversion to obtain reliable estimates of the crustal thickness beneath the seismic stations. Our preliminary results indicate that the crust beneath Sabah (in northern Borneo), which is a post-subduction setting, appears to be much more complex and is overall thicker (more than 35 km) than the rest of the island. In addition, we find that crustal thickness varies between different tectonic blocks defined from previous surface mapping, with the thinnest crust (23 to 25 km) occurring beneath Sarawak in the west-northwest as well as in the east of Kalimantan.</p> <p>We also present preliminary results from Virtual Deep Seismic Sounding (VDSS) in northern Borneo, where from the RF results we know that there is thick and complex crust. VDSS is able to produce well constrained crustal thickness results in regions where the RF analysis has difficulty recovering the Moho, likely due to complexities such as thick sedimentary basins and obducted ophiolite sequences.</p> </div> </div> </div>

Crustal thickness and adakite occurrence in the Philippines: Is there a relationship?

Island Arc ◽  
2008 ◽  
Vol 17 (4) ◽  
pp. 421-431 ◽  
Author(s):  
Carla B. Dimalanta ◽  
Graciano P. Yumul, Jr
Keyword(s):  
Crustal Thickness ◽  
The Philippines

scholarly journals Melt equilibration depths as sensors of lithospheric thickness during Eurasia-Arabia collision and the uplift of the Anatolian Plateau

Geology ◽  
2019 ◽  
Vol 47 (10) ◽  
pp. 943-947 ◽  
Author(s):  
M.R. Reid ◽  
J.R. Delph ◽  
M.A. Cosca ◽  
W.K. Schleiffarth ◽  
G. Gençalioğlu Kuşcu
Keyword(s):  
Late Miocene ◽  
Large Scale ◽  
Middle Miocene ◽  
Volcanic Rocks ◽  
Suture Zone ◽  
Arabian Plate ◽  
Seismic Structure ◽  
Eurasian Plate ◽  
Lithospheric Thickness ◽  
Anatolian Plateau

Abstract A co-investigation of mantle melting conditions and seismic structure revealed an evolutionary record of mantle dynamics accompanying the transition from subduction to collision along the Africa-Eurasia margin and the >1 km uplift of the Anatolian Plateau. New 40Ar/39Ar dates of volcanic rocks from the Eastern Taurides (southeast Turkey) considerably expand the known spatial extent of Miocene-aged mafic volcanism following a magmatic lull over much of Anatolia that ended at ca. 20 Ma. Mantle equilibration depths for these chemically diverse basalts are interpreted to indicate that early to middle Miocene lithospheric thickness in the region varied from ∼50 km or less near the Bitlis suture zone to ∼80 km near the Inner Tauride suture zone. This southward-tapering lithospheric base could be a vestige of the former interface between the subducted (and now detached) portion of the Arabian plate and the overriding Eurasian plate, and/or a reflection of mantle weakening associated with greater mantle hydration trenchward prior to collision. Asthenospheric upwelling driven by slab tearing and foundering along this former interface, possibly accompanied by convective removal of the lithosphere, could have led to renewed volcanic activity after 20 Ma. Melt equilibration depths for late Miocene and Pliocene basalts together with seismic imaging of the present lithosphere indicate that relatively invariant lithospheric thicknesses of 60–70 km have persisted since the middle Miocene. Thus, no evidence is found for large-scale (tens of kilometers) Miocene delamination of the lower lithosphere from the overriding plate, which has been proposed elsewhere to account for late Miocene and younger uplift of Anatolia.

Syllidae (Annelida) from East Timor and the Philippines (Pacific Ocean), with the description of three new species of Syllis Savigny in Lamarck, 1818

Zootaxa ◽  
2020 ◽  
Vol 4834 (2) ◽  
pp. 231-263
Author(s):  
MARÍA JOSÉ MARTÍNEZ ◽  
GUILLERMO SAN MARTÍN
Keyword(s):  
First Record ◽  
The Philippines ◽  
East Timor ◽  
Marine Biodiversity ◽  
Tropical Asia ◽  
The North ◽  
Indonesian Archipelago ◽  
Small Collection ◽  
Three New Species ◽  
Anterior Segments

East Timor is an island located to the south of the Indonesian Archipelago and to the north of Australia, between the Indian and Pacific Oceans. It is included in the Coral Triangle and houses an amazing quantity of marine biodiversity. However, only two species of Syllidae (Annelida) have been reported up to now: Trypanosyllis migueli and T. devae. Based on a small collection from the Australian Museum, we have identified nine genera and 17 species: Brevicirrosyllis mariae, Opisthodonta morena, Sphaerosyllis densopapillata, Branchiosyllis australis, B. exilis, B. maculata, B. verruculosa, Haplosyllis djiboutiensis, Opisthosyllis brunnea, Syllis alternata, S. broomensis, S. corallicola, S. erikae, S. gerlachi, S. hyalina, S. setoensis and Trypanosyllis luzonensis. This is the first record of S. gerlachi outside the Indian Ocean, and B. mariae, O. morena, S. densopapillata, H. djiboutiensis, S. corallicola and S. erikae have not been previously reported in tropical Asia. A specimen of Parahaplosyllis sp. could not be identified due to its poor condition. Three species belonging to Syllis are herein described as new: S. cambuk n. sp. has a large size body, with anterior segments much wider and shorter than posterior ones, long whip-shaped dorsal cirri and bidentate midbody and posterior chaetae, with both teeth equal in size and shape; Syllis hampirmenyatu n. sp. has three chaetae per posterior parapodium, with short and wide blades appearing to be fused with shafts, but still clearly distinguishable from each other, bidentate, with proximal tooth clearly smaller and thinner than distal one; and S. maganda n. sp. is easily recognizable because of its spectacular orange and blue colouration, only observable in living specimens, with broad transverse red stripes on the dorsum forming a distinctive pattern and red spots on the cirri and prostomium observable in both living and fixed specimens. Additionally, Philippine samples from the Museo Nacional de Ciencias Naturales of Madrid have been examined corresponding to S. maganda n. sp. A Philippine specimen of S. maganda n. sp. had a small unidentified specimen of Haplosyllis attached to a posterior dorsal cirrus, which is the first documented case of such an interaction between two species of Syllidae. This provisionally called Haplosyllis sp. is characterized by its simple chaetae with short spur and two very long, distinct curved teeth, very close to each other. A regenerated prostomium and a stolon were also found in other Philippine specimens of S. maganda n. sp. 

The Chile subduction zone : Nature of the lithosphere between alternating regions of slow earthquakes versus non slow earthquakes

2020 ◽  
Author(s):  
Pousali Mukherjee ◽  
Yoshihiro Ito ◽  
Emmanuel S. Garcia ◽  
Raymundo Plata-Martinez ◽  
Takuo Shibutani
Keyword(s):  
Subduction Zones ◽  
Receiver Function ◽  
Function Analysis ◽  
Fluid Distribution ◽  
Inversion Method ◽  
Megathrust Earthquakes ◽  
Slow Earthquake ◽  
Slow Earthquakes ◽  
Receiver Function Analysis ◽  
Earthquake Area

<p>Subduction zones host some of the greatest megathrust earthquakes in the world. Slow earthquakes have been discovered around the subduction zones of the Pacific rim very close to megathrust earthquakes. Investigating the lithosphere of the slow earthquake area versus non slow-earthquake area in subduction zones is crucial in understanding the role of the internal structure to control slow earthquakes. In this study, we investigate the lithospheric structure of stations in the slow earthquake area and non slow-earthquake areas in Chile using receiver function analysis and inversion method using teleseismic earthquakes. Here we focus on, especially the Vp/Vs ratios from both slow and non-slow earthquake areas, because the Vp/Vs ratio is sensitive to the fluid distribution in the lithosphere; the fluid distribution possibly controls the potential occurrence of slow earthquakes. Additionally, the nature of the slab can also play a crucial factor. The Vp/Vs ratio results across depth shows significantly higher value in the deeper oceanic slab region beneath the stations in the slow earthquake areas with higher contrast at the boundary.</p>

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