Sedimentation and volcanism in the Panamanian Cretaceous intra-oceanic arc and fore-arc: New insights from the Azuero peninsula (SW Panama)

2013 ◽  
Vol 184 (1-2) ◽  
pp. 35-45 ◽  
Author(s):  
Isaac Corral ◽  
David Gómez-Gras ◽  
Albert Griera ◽  
Mercè Corbella ◽  
Esteve Cardellach
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Water Environment ◽  
Sediment Supply ◽  
Lava Flows ◽  
Turbidity Currents ◽  
Volcanic Arc ◽  
Basement Rocks ◽  
Volcanic Source ◽  
Azuero Peninsula

Abstract The Azuero Peninsula, located in SW Panama, is a region characterized by a long-lived intra-oceanic subduction zone. Volcanism began in Late Cretaceous time, as the result of subduction of the Farallon plate beneath the Caribbean plate. Usually, ancient volcanic arcs related to intra-oceanic subduction zones are not preserved, because they are in areas with difficult access or covered by modern volcanic arc material. However, on the Azuero peninsula, a complete section of the volcanic arc together with arc basement rocks provides the opportunity to study the sedimentation and volcanism in the initial stages of volcanic arc development. The lithostratigraphic unit which records fore-arc evolution is the “Río Quema” Formation (RQF), a volcanic apron composed of volcanic and volcaniclastic sedimentary rocks interbedded with hemipelagic limestones, submarine dacite lava domes, and intruded by basaltic-andesitic dikes. The “Río Quema” Formation, interpreted as a fore-arc basin infilling sequence, lies discordantly on top of arc basement rocks. The exceptionally well exposed arc basement, fore-arc basin, volcanic arc rocks and arc-related intrusive rocks provide an unusual opportunity to study the relationship between volcanism, sedimentation and magmatism during the arc development, with the objective to reconstruct its evolution. The “Río Quema” Formation can be divided into three groups: 1) proximal apron, a sequence dominated by lava flows, interbedded with breccias, mass flows and channel fill, all intruded by basaltic dikes. The rocks represent the nearest materials to the volcanic source, reflecting a coarse sediment supply. This depositional environment is similar to gravel-rich fan deltas and submarine ramps; 2) medial apron, characterized by a volcanosedimentary succession dominated by andesitic lava flows, polymictic volcanic conglomerates and crystal-rich sandstones with minor pelagic sediments and turbidites. These rocks were deposited from high-density turbidity currents and debris flows, directly derived from erupted material and gravitational collapse of an unstable volcanic edifice or volcaniclastic apron; 3) distal apron, a thick succession of sandy to muddy volcaniclastic rocks, interbedded with pelagic limestones and minor andesitic lavas, intruded by dacite domes and by basaltic to andesitic dikes. Bedforms and fossils suggest a quiet, relatively deep-water environment characterized by settling of clay and silt (claystone, siltstone) and by dilute turbidity currents of reworked volcaniclastic detritus. The timing of the initial stages of the volcanic arc has been constrained through a biostratigraphic study, using planktonic foraminifera and radiolarian species. The fossil assemblage indicates that the age of the “Río Quema” Formation ranges from Late Campanian to Maastrichtian, providing a good constraint for the development of the volcanic arc and volcaniclastic apron, during the initial stages of an intra-oceanic subduction zone.

scholarly journals Controls on the origin and evolution of deep-ocean trench-axial channels

Geology ◽  
2021 ◽  
Author(s):  
Adam D. McArthur ◽  
Daniel E. Tek
Keyword(s):  
Subduction Zones ◽  
Three Dimensional ◽  
Plate Boundary ◽  
Deep Ocean ◽  
Sediment Supply ◽  
Turbidity Currents ◽  
Primary Control ◽  
Sediment Distribution ◽  
Origin And Evolution ◽  
Axial Channel

The type and volume of sediment entering subduction zones affects the style of plate-boundary deformation and thus sedimentary and tectonic cycles. Because submarine channels significantly increase the transport efficiency of turbidity currents, their presence or absence in subduction trenches is a primary control on trench fill. To date, comprehensive architectural characterization of trench-axial channels has not been possible, undermining efforts to identify the factors controlling their initiation and evolution. Here, we describe the evolution of the Hikurangi Channel, which traverses the Hikurangi Trench, offshore New Zealand. Analysis of two- and three-dimensional seismic data reveals that the channel was present only during the last ~3.5 m.y. of the ~27 m.y. of the trench’s existence; its inception and propagation resulted from increased sediment supply to the trench following amplified hinterland exhumation. To test if the controls on the evolution of the Hikurangi Channel are universal, multivariate statistical analysis of the geomorphology of subduction trenches globally is used to investigate the formative conditions of axial channels in modern trenches. Terrigenous sediment supply and thickness of sediment cover in a trench are the dominant controls; subsidiary factors such as trench length and rugosity also contribute to the conditions necessary for trench-axial channel development. Axial channels regulate sediment distribution in trenches, and this varies temporally and spatially as a channel propagates along a trench. The presence of a trench-axial channel affects plate-boundary mechanics and has implications for the style of subduction-margin deformation.

Ciletuh Subduction, West Java - New Findings, New Problems: Regional Implications to Cretaceous-Paleogene Convergence of Sundaland Margin and Its Petroleum Geology

2021 ◽  
Author(s):  
A. H. Satyana
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Field Studies ◽  
Point Of View ◽  
Island Arc ◽  
West Java ◽  
Central Java ◽  
Basement Rocks ◽  
New Findings ◽  
Cretaceous Subduction

Ciletuh, southwest Java has been well known as one of the places in Java where pre-Tertiary basement rocks are exposed (Verbeek and Fennema, 1896; Duyfjes, 1940; van Bemmelen, 1949; Sukamto, 1975). In plate tectonic point of view, Ciletuh has been known as place outcropping melange complex related to pre-Tertiary oceanic plate subduction (Thayyib et al., 1977). Ciletuh subduction regionally has been linked to the Cretaceous subduction zones of Luk Ulo/Karang Sambung (Central Java) and Meratus Mountains (South Kalimantan) (Hutchison, 1973; Asikin 1974; Hamilton, 1979). Ciletuh subduction however, has not been dated using metamorphic rocks formed in its subduction zone. Its link to Luk Ulo and Meratus subduction zone only based on the presence of melange, which also lacks of data Meanwhile, subduction zones of Luk Ulo and Meratus have been dated and analysed. We herewith present the results of new field studies and various analyses carried out in the last five years of the Ciletuh subduction complex. The indication of Cretaceous subduction has not found from the date measurement, Ciletuh shows Eocene related subduction. Most of the ophiolites were island-arc tholeiitic or island-arc basalt formed in supra-subduction zone. The overlying olistostrome deposits were younger than previously considered and lasted until early/middle Miocene. Some of the basaltic pillowed lava is considered as part of the ophiolite, while the ones at Gunung Badak is more likely a part of the early Miocene Jampang volcanism. Link of Ciletuh to Early Cretaceous subduction of Luk Ulo is not supported by geochronological data. The new knowledge of Ciletuh subduction implies the pre-Tertiary and Paleogene geology of Java, and petroleum prospectivities of the Paleogene objectives of southern West Java. New problems arise and need more field data and analyses to find out the answers.

scholarly journals Up the down escalator: the exhumation of (ultra)-high pressure terranes during on-going subduction

2012 ◽  
Vol 4 (1) ◽  
pp. 745-781 ◽  
Author(s):  
C. J. Warren
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Continental Crust ◽  
Subduction Zones ◽  
Crustal Material ◽  
Time And Space ◽  
Ultra High Pressure ◽  
Tectonic Environment ◽  
Tectonic Style ◽  
Weak Material

Abstract. The exhumation of high and ultra-high pressure rocks is ubiquitous in Phanerozoic orogens created during continental collisions, and is common in many ocean-ocean and ocean-continent subduction zone environments. Three different tectonic environments have previously been reported, which exhume deeply buried material by different mechanisms and at different rates. However it is becoming increasingly clear that no single mechanism dominates in any particular tectonic environment, and the mechanism may change in time and space within the same subduction zone. In order for buoyant continental crust to subduct, it must remain attached to a stronger and denser substrate, but in order to exhume, it must detach (and therefore at least locally weaken) and be initially buoyant. Denser oceanic crust subducts more readily than more buoyant continental crust but exhumation must be assisted by entrainment within more buoyant and weak material such as serpentinite or driven by the exhumation of structurally lower continental crustal material. Weakening mechanisms responsible for the detachment of crust at depth include strain, hydration, melting, grain size reduction and the development of foliation. These may act locally or may act on the bulk of the subducted material. Metamorphic reactions, metastability and the composition of the subducted crust all affect buoyancy and overall strength. Subduction zones change in style both in time and space, and exhumation mechanisms change to reflect the tectonic style and overall force regime within the subduction zone. Exhumation events may be transient and occur only once in a particular subduction zone or orogen, or may be more continuous or occur multiple times.

scholarly journals Analysis of Stress Drop Variations in Fault and Subduction Zones of Maluku and Halmahera Earthquakes in 2019

2019 ◽  
Vol 9 (2) ◽  
pp. 152
Author(s):  
Rahmat Setyo Yuliatmoko ◽  
Telly Kurniawan
Keyword(s):  
Subduction Zone ◽  
Stress Drop ◽  
Subduction Zones ◽  
Slip Rate ◽  
Disaster Mitigation ◽  
Mitigation Measures ◽  
Reverse Fault ◽  
Nonlinear Inversion ◽  
Rock Structure ◽  
Geological Conditions

The amount of stress released by an earthquake can be calculated with a stress drop, the stress ratio before and after an earthquake where the stress accumulated in a fault or a subduction zone is immediately released during an earthquake. The purpose of this research is to calculate the amount of stress drop in faults and subduction in Maluku and Halmahera and their variations and relate them to the geological conditions in the area so that the tectonic characteristics in the area can be identified. This research employed mathematical analysis and the Nelder Mead Simplex nonlinear inversion methods. The results show that Maluku and Halmahera are the area with complex tectonic conditions and large earthquake impacts. The Maluku sea earthquake generated a stress drop of 0.81 MPa with a reverse fault mechanism in the zone of subduction, while for the Halmahera earthquake the stress drop value was 52.72 MPa, a typical strike-slip mechanism in the fault zone. It can be concluded that there is a difference in the stress drop between the subduction and fault zones; the stress drop in the fault was greater than that in the subduction zone due to different rock structure and faulting mechanisms as well as differences in the move slip rate that plays a role in the process of holding out the stress on a rock. This information is very important to know the amount of pressure released from the earthquake which has a very large impact as part of disaster mitigation measures.

Subduction zone heterogeneity observed across the magnitude spectrum for megathrust earthquakes

2021 ◽  
Author(s):  
Susan Bilek ◽  
Emily Morton
Keyword(s):  
Spatial Heterogeneity ◽  
Subduction Zone ◽  
Stress Drop ◽  
Subduction Zones ◽  
Cascadia Subduction Zone ◽  
Ocean Bottom ◽  
Small Earthquake ◽  
Megathrust Earthquakes ◽  
Seismic Slip ◽  
Subduction Zone Earthquakes

<p>Observations from recent great subduction zone earthquakes highlight the influence of spatial geologic heterogeneity on overall rupture characteristics, such as areas of high co-seismic slip, and resulting tsunami generation.  Defining the relevant spatial heterogeneity is thus important to understanding potential hazards associated with the megathrust. The more frequent, smaller magnitude earthquakes that commonly occur in subduction zones are often used to help delineate the spatial heterogeneity.  Here we provide an overview of several subduction zones, including Costa Rica, Mexico, and Cascadia, highlighting connections between the small earthquake source characteristics and rupture behavior of larger earthquakes.  Estimates of small earthquake locations and stress drop are presented in each location, utilizing data from coastal and/or ocean bottom seismic stations.  These seismicity characteristics are then compared with other geologic and geophysical parameters, such as upper and lower plate characteristics, geodetic locking, and asperity locations from past large earthquakes.  For example, in the Cascadia subduction zone, we find clusters of small earthquakes located in regions of previous seamount subduction, with variations in earthquake stress drop reflecting potentially disrupted upper plate material deformed as a seamount passed.  Other variations in earthquake location and stress drop can be correlated with observed geodetic locking variations. </p>

scholarly journals Illuminating subduction zone rheological properties in the wake of a giant earthquake

2019 ◽  
Vol 5 (12) ◽  
pp. eaax6720 ◽  
Author(s):  
Jonathan R. Weiss ◽  
Qiang Qiu ◽  
Sylvain Barbot ◽  
Tim J. Wright ◽  
James H. Foster ◽  
...  
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Three Dimensional ◽  
Surface Strain ◽  
Postseismic Deformation ◽  
Crust And Upper Mantle ◽  
Plate Convergence ◽  
Maule Earthquake ◽  
History Of ◽  
Dependent Viscosity

Deformation associated with plate convergence at subduction zones is accommodated by a complex system involving fault slip and viscoelastic flow. These processes have proven difficult to disentangle. The 2010 Mw 8.8 Maule earthquake occurred close to the Chilean coast within a dense network of continuously recording Global Positioning System stations, which provide a comprehensive history of surface strain. We use these data to assemble a detailed picture of a structurally controlled megathrust fault frictional patchwork and the three-dimensional rheological and time-dependent viscosity structure of the lower crust and upper mantle, all of which control the relative importance of afterslip and viscoelastic relaxation during postseismic deformation. These results enhance our understanding of subduction dynamics including the interplay of localized and distributed deformation during the subduction zone earthquake cycle.

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.

Geology, petrology and tectonomagmatic evolution of the plutonic crustal rocks of the Sabzevar ophiolite, NE Iran

2013 ◽  
Vol 150 (5) ◽  
pp. 862-884 ◽  
Author(s):  
MORTEZA KHALATBARI JAFARI ◽  
HASSAN A. BABAIE ◽  
MOJTABA MIRZAIE
Keyword(s):  
Subduction Zone ◽  
Subduction Zones ◽  
Island Arc ◽  
Magma Chambers ◽  
Northern Margin ◽  
Crustal Rocks ◽  
Microscopic Studies ◽  
Element Enrichment ◽  
Spider Diagrams ◽  
Ocean Ridge

AbstractThe plutonic crustal sequence exposed northeast of Sabzevar is part of the ophiolitic belt of Sabzevar that occurs along the northern margin of the Central Iran micro-continent. The sequence includes olivine and pyroxene gabbro with cumulate characteristics, isotropic gabbro, foliated gabbro and a diabase sheeted dyke complex cut by wehrlite and olivine websterite intrusions, and pegmatite gabbro and plagiogranite as small intrusions and dykes. The sequence is comparable to gabbros in known ophiolite complexes. Microscopic studies show an abundance of the mesocumulate and heteradcumulate textures that represent open system magma chambers, which are common in supra-subduction zones. The olivine → plagioclase → clinopyroxene → ± orthopyroxene → amphibole trend of mineralization in the gabbros, similar to mid-ocean ridge basalt (MORB), and olivine → clinopyroxene → ± orthopyroxene → plagioclase → amphibole, similar to arc rocks, indicate the diversity in the formation of these rocks, and represent petrographic evidence of their formation in a supra-subduction zone. The rocks have calc-alkaline to tholeiitic affinities, and niobium depletion in the spider diagrams of diabase that matches the patterns of island arc magma. These patterns, and the light rare earth element enrichment of the diabase and plagiogranite, suggest the effect and introduction of the fluids, originating from the subducting slab, beneath the mantle wedge. The low titanium compositions, matching those of arc diabase and plagiogranite, plot in the island arc to MORB tectonomagmatic fields, and suggest formation of the Sabzevar ophiolitic plutonic crustal sequence in a supra-subduction zone during Late Cretaceous time.

Mesozoic – early Cenozoic volcanism, plutonism, and mineralization in southern British Columbia: A plate tectonic synthesis

1977 ◽  
Vol 14 (7) ◽  
pp. 1611-1624 ◽  
Author(s):  
John R. Griffiths
Keyword(s):  
British Columbia ◽  
Subduction Zone ◽  
Subduction Zones ◽  
Tectonic Setting ◽  
Spatial Relationship ◽  
Plate Tectonic ◽  
Time Space ◽  
Cenozoic Volcanism ◽  
Volcanic Belts ◽  
Early Cenozoic

Three time–space profiles have been constructed using geologic data from British Columbia between 49° N and 56° N. They illustrate variations across the Cordillera, (1) in the stratigraphic and tectonic setting of volcanism, (2) in the age and modal type of granitoids, and (3) in the distribution and types of copper and lead deposits related to volcanic and plutonic rocks. These profiles provide the basis for a plate tectonic synthesis of the Mesozoic–Cenozoic geology, illustrated by six true-scale cross sections.The preferred model has, in the Triassic, two eastward-dipping subduction zones, giving rise to the copper-rich Karmutsen and Nicola–Takla volcanics respectively. After collision of the two volcanic belts by the Early Jurassic, a single eastward-dipping subduction zone remained active until the Eocene. Magmas produced by partial melting and fractionation of subducted lithosphere occurred across the western 300 km of the Cordillera, leading to thickening of the crust, and eventually to anatectic melting to generate large batholiths now containing pendants of volcanics. Jurassic and later geologic and metallogenic events across the eastern 500 km of the Cordillera are the results of an increased heat flux through inhomogeneous crust of varying thickness, comprised of relict ocean floor, continental margin sediments, older volcanics, and ancient cratonic basement. This results in patterns of metamorphism, volcanism, and plutonism which have no simple spatial relationship to the subduction zone.

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