The NE Lau Basin: Widespread and Abundant Hydrothermal Venting in the Back-Arc Region Behind a Superfast Subduction Zone

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.

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

Geological Journal ◽

10.1002/gj.3345 ◽

2018 ◽

Vol 54 (6) ◽

pp. 3489-3508 ◽

Cited By ~ 1

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

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

BSGF - Earth Sciences Bulletin ◽

10.2113/175.5.443 ◽

2004 ◽

Vol 175 (5) ◽

pp. 443-460 ◽

Cited By ~ 53

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.

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Ophiolitic Pyroxenites Record Boninite Percolation in Subduction Zone Mantle

Minerals ◽

10.3390/min9090565 ◽

2019 ◽

Vol 9 (9) ◽

pp. 565 ◽

Cited By ~ 2

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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Effects of plate boundary geometry and kinematics on mantle melting beneath the back-arc spreading centers along the Lau Basin

Earth and Planetary Science Letters ◽

10.1016/j.epsl.2010.08.004 ◽

2010 ◽

Vol 298 (3-4) ◽

pp. 334-346 ◽

Cited By ~ 16

Author(s):

Nicholas Harmon ◽

Donna K. Blackman

Keyword(s):

Plate Boundary ◽

Mantle Melting ◽

Lau Basin ◽

Spreading Centers ◽

Boundary Geometry ◽

Back Arc ◽

Geometry And Kinematics

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Late Cenozoic calc-alkaline volcanism over the Payenia shallow subduction zone, South-Central Andean back-arc (34°30′–37°S), Argentina

Journal of South American Earth Sciences ◽

10.1016/j.jsames.2015.09.010 ◽

2015 ◽

Vol 64 ◽

pp. 365-380 ◽

Cited By ~ 28

Author(s):

Vanesa D. Litvak ◽

Mauro G. Spagnuolo ◽

Andrés Folguera ◽

Stella Poma ◽

Rosemary E. Jones ◽

...

Keyword(s):

Subduction Zone ◽

Late Cenozoic ◽

Calc Alkaline ◽

South Central ◽

Alkaline Volcanism ◽

Shallow Subduction ◽

Back Arc

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The ophiolites of the Tibetan Geotraverses, Lhasa to Golmud (1985) and Lhasa to Kathmandu (1986)

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1988.0127 ◽

1988 ◽

Vol 327 (1594) ◽

pp. 215-238 ◽

Cited By ~ 107

Keyword(s):

Subduction Zone ◽

Oceanic Lithosphere ◽

Island Arc ◽

Passive Margin ◽

Jinsha River ◽

Geochemical Composition ◽

The North ◽

Kunlun Mountains ◽

Slow Spreading ◽

Back Arc

Ophiolite belts are found in Tibet along the Zangbo, Banggong and Jinsha River Sutures and in the Anyemaqen mountains, the eastern extension of the Kunlun mountains. Where studied, the Zangbo Suture ophiolites are characterized by: apparently thin crustal sequences (3-3.5 k m ); an abundance of sills and dykes throughout the crustal and uppermost mantle sequences; common intraoceanic melanges and unconformities; and an N-MORB petrological and geochemical composition. The ophiolites probably formed within the main neo-Tethyan ocean and the unusual features may be due to proximity to ridge-transform intersections, rather than to genesis at very slow -spreading ridges as the current consensus suggests. The Banggong Suture ophiolites have a supra-subduction zone petrological and geochemical composition — although at least one locality in the Ado Massif shows MORB characteristics. However, it is also apparent that the dykes and lavas show a regional chemical zonation, from boninites and primitive island arc tholeiites in the south of the ophiolite belt, through normal island arc tholeiites in the central belt to island arc tholeiites transitional to N-MORB in the north. The ophiolites could represent fragments of a fore-arc, island arc, back-arc complex developed above a Jurassic, northward-dipping subduction zone and emplaced in several stages during convergence of the Lhasa and Qiangtang terranes. The ophiolites of the Jinsha River Suture have a N-MORB composition where analysed, but more information is needed for a proper characterization. The Anyemaqen ophiolites, where studied, have a within-plate tholeiite composition and may have originated at a passive margin: it is not, however, certain whether true oceanic lithosphere, as opposed to strongly attenuated continental lithosphere, existed in this region.

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Submarine back-arc lava with arc signature: Fonualei Spreading Center, northeast Lau Basin, Tonga

Journal of Geophysical Research Atmospheres ◽

10.1029/2007jb005451 ◽

2008 ◽

Vol 113 (B8) ◽

Cited By ~ 43

Author(s):

Nicole S. Keller ◽

Richard J. Arculus ◽

Jörg Hermann ◽

Simon Richards

Keyword(s):

Spreading Center ◽

Lau Basin ◽

Back Arc

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The Oman ophiolite as a Cretaceous arc-basin complex: evidence and implications

Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences ◽

10.1098/rsta.1981.0066 ◽

1981 ◽

Vol 300 (1454) ◽

pp. 299-317 ◽

Cited By ~ 308

Keyword(s):

Subduction Zone ◽

Oceanic Crust ◽

Significant Proportion ◽

Dyke Swarm ◽

Geochemical Analysis ◽

Oman Ophiolite ◽

Geochemical Evidence ◽

Tectonic Development ◽

High Level ◽

Back Arc

Geological and geochemical evidence suggest that the Oman ophiolite is a fragment of a submarine arc-basin complex formed above a short-lived subduction zone in the mid-Cretaceous. Detailed studies of the lava stratigraphy and the intrusive relationships of dykes, sills and high-level plutons provide further evidence for the magmatic and tectonic development of the complex in question. Four consecutive events can be recognized to have taken place before emplacement: (1) eruption of basalts of island arc affinity onto pre-existing (Triassic) oceanic crust; (2) creation of new oceanic crust by backarc spreading; (3) intrusion of magma into this back-arc oceanic crust accompanied by eruption of basalts and andesites from discrete volcanic centres; (4) further intrusion of magma accompanied by uplift and eruption of basalts and rhyolites in submarine graben. A combined structural and geochemical analysis of the dyke swarm indicates that extension took place in approximately a N-S (ridge) and an ESE-WNW (leaky transform) direction relative to an inferred direction of subduction to the NE, and that a small but significant proportion of the sheeted dykes were injected during the ‘arc’ rather than the earlier ‘back-arc spreading’ episode. These various observations can be explained in terms of the progressive response of a non-isotropic lithosphere to the stresses induced during subduction.

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