Melt stagnation in peridotites from the Godzilla Megamullion Oceanic Core Complex, Parece Vela Basin, Philippine Sea

Loocke, M. P.; Snow, J. E.; Ohara, Yasuhiko

doi:10.1016/j.lithos.2013.09.005

Cited by 25 publications

(29 citation statements)

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“…) Tomoda et al, 1975;Watts and Weissel, 1975;Kobayashi and Nakada, 1978;Shih, 1980;Chamot-Rooke et al, 1987 , 2010, 2011aLoocke et al, 2013;Sanfilippo et al, 2013;Michibayashi et al, 2014;Spencer and Ohara, 2014;Tani et al, 2011) …”

mentioning

confidence: 99%

Geoscientific Characteristics of the Seafloor of the Southern Ocean of Japan Revealed by Japan's Continental Shelf Survey

Ohara

Kato

Yoshida

et al. 2015

Journal of Geography(Chigaku Zasshi)

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confidence: 99%

Geoscientific Characteristics of the Seafloor of the Southern Ocean of Japan Revealed by Japan's Continental Shelf Survey

Ohara

Kato

Yoshida

et al. 2015

Journal of Geography(Chigaku Zasshi)

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“…Therefore, the investigated, non-equilibrated peridotites demonstrate a cooling evolution that is apparently unrelated to their assumed inherited geotherm. It is supposed that quick exhumation can prevent re-equilibration of refertilized peridotites (e.g., Loocke et al 2013). The studied harzburgite varieties display no remarkable signs of recovery or grain growth after deformation, implying that they followed a 'cold exhumation path' (e.g., Müntener and Piccardo 2003).…”

Section: Melt Stagnation and Its Implications For Mantle Exhumationmentioning

confidence: 97%

“…Therefore, olivine-rich harzburgite served as a sort of lithospheric 'sponge' (e.g., Müntener et al 2010) that was substantially affected by melt stagnation. Melt stagnation requires pervasive wetting of grain boundaries (Seyler et al 2007) and melt accretion at crystal triple junctions (Loocke et al 2013). The recrystallized nature of olivine in the most refractory harzburgite probably facilitated local melt storage in the southern Vourinos mantle suite.…”

Section: Melt Stagnation and Its Implications For Mantle Exhumationmentioning

confidence: 99%

Physiognomy and timing of metasomatism in the southern Vourinos ultramafic suite, NW Greece: a chronicle of consecutive episodes of melt extraction and stagnation in the Neotethyan lithospheric mantle

Kapsiotis

2015

Int J Earth Sci (Geol Rundsch)

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their multifarious origin in a progressively changing, in space and time, geotectonic setting. Chromian spinel chemistry (Cr# vs. TiO 2 ) provides evidence for two consecutive melt-peridotite interaction events pertaining to patent metasomatism. The first incident is related to the release of IAT melts from the deep parts of the southern Vourinos mantle segment, which reacted with harzburgites transforming them into olivine-rich harzburgites and replacive dunites, whereas mixing of different pulses of IAT melts with distinct SiO 2 activities generated heterogeneously deformed, cumulitic dunites. The second event is linked to the genesis of MORB/IAT magmas that originally invaded harzburgites. The MORB/IAT melts, although intensely reactive at the stage of harzburgite impregnation, lost their ability to react and stagnated in the peridotite groundmass as they approached the conceivable boundary with olivine-rich harzburgite. Microtextural observations and compositional data support that the interstitial, unstrained clinopyroxene ± olivine aggregates recognized in the harzburgite varieties represent intergranular melt blebs that 'chilled' in the mantle during an episode of rapid lithosphere exhumation. This is further corroborated by the absence of lavas with MORB/ IAT geochemical affinities from the Vourinos extrusive sequence. Microstructural features of websterite veins suggest that their genesis cannot be ascribed to the melts that penetrated the peridotites that cross cut. In contrast, they retain marks of olivine assimilation from the wall rocks that was facilitated by interaction with olivineundersaturated, arc-derived tholeiitic melts released at a late phase from the ultradepleted southern Vourinos mantle suite. AbstractThe southern Vourinos massif, located in the Hellenides orogenic belt, forms part of the mantle section of the homonymous Neotethyan ophiolite complex in the NW Greek mainland. The southern domain of the massif is comprised voluminous and strained peridotite outcrops with variable pyroxene and olivine modal abundances, ranging from harzburgite (sensu stricto) to olivine-rich harzburgite and fine-to coarse-grained dunite. These peridotites are intruded by a complex network of undeformed websterite to olivine-rich websterite dykes. The peridotite lithologies are characterized by high Cr# [=Cr/(Cr + Al)] values in Cr-spinel (0.54-0.80), elevated Mg# [=Mg/(Mg + Fe 2+ )] ratios in olivine (0.91-0.94), poor Al 2 O 3 content in clinopyroxene (up to 1.85 wt%) and very low bulk-rock abundances of Al 2 O 3 (up to 0.66 wt%), CaO (up to 0.84 wt%), V (up to 45 ppm), Sc (up to 11 ppm) and REE, which are suggestive of their strongly depleted nature. They also display a wide range of fO 2 values that vary between the fayalite-magnetite-quartz (FMQ-2) and FMQ+1 buffers, signifying their genesis under anoxic to oxidizing conditions. Simple batch and fractional melting models cannot satisfactorily explain their ultradepleted composition, whereas whole-rock Ni/Yb versus Yb systematics can be simulated by up to...

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“…b, a and b) at dredge site CSS33‐D1 (at 16°23′N, 139°36′E; 2659 m depth) by S/V Takuyo in 1995. They noted the presence of pseudomorphed plagioclase in the peridotites, later recognized as one of the important characteristics of the Godzilla peridotites (Ohara et al ; Ohara ; Loocke et al ).…”

Section: Japan's Extended Continental Shelf Survey Program In 1990s Amentioning

confidence: 99%

“…After the discovery of the Godzilla Megamullion (Ohara et al ), more than 20 cruises explored the OCC and the Parece Vela Basin (Table ). Important results from these cruises were published in Ohara et al (, ), Harigane et al (, , ), Tani et al (), Loocke et al (), Sanfilippo et al (), Michibayashi et al (), and Spencer and Ohara (). The aim of this article is to provide a sound background for studying the Godzilla Megamullion, summarizing the necessary information that will help accelerate ongoing studies by the ocean lithosphere community.…”

Section: Introductionmentioning

confidence: 96%

The Godzilla Megamullion, the largest oceanic core complex on the earth: a historical review

Ohara

2015

Island Arc

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The Godzilla Megamullion is the largest known oceanic core complex (OCC) on the Earth, located in the Parece Vela Basin in the Philippine Sea. In this article, the history of Godzilla Megamullion study is reviewed for the first time, dividing it into three major phases: (i) the early studies done before Japan's extended continental shelf survey program; (ii) the studies during Japan's extended continental shelf survey program that discovered the OCC; and (iii) the studies by the post-discovery cruises. The early studies included an interpretation of US nautical chart of the southwestern Pacific and the site surveys for Deep Sea Drilling Project cruises (DSDP Legs 6, 31 and 59). The early studies recognized the presence of the Parece Vela Rift, the extinct spreading axis of the Parece Vela Basin, and established the currently accepted model that the Philippine Sea evolved with eastward progression of backarc spreading and arc migration. The modern understanding of the Parece Vela Basin comes from Japan's extended continental shelf survey program. The program revealed the ultramafic petrology as well as a two-stage evolution model of the basin. Following these results, the discovery of the Godzilla Megamullion was made in 2001. The studies by the post-discovery cruises further revealed important characteristics of the OCC, such as the presence of abundant plagioclase-bearing peridotite and the systematic temporal changes in both deformation microstructures and composition of plagioclase and amphibole in gabbroic mylonites and ultramylonites. Zircon U-Pb ages of gabboric and leucocratic rocks indicate that the terminal phase of Parece Vela Basin spreading was with a significant decline in spreading rate and asymmetry accompanying formation of the Godzilla Megamullion. The estimated denudation rate of the OCC was approximately 2.5 cm/yr; significantly slower than the previous estimate based on poorly constrained magnetic data.

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Melt stagnation in peridotites from the Godzilla Megamullion Oceanic Core Complex, Parece Vela Basin, Philippine Sea

Cited by 25 publications

References 69 publications

Geoscientific Characteristics of the Seafloor of the Southern Ocean of Japan Revealed by Japan's Continental Shelf Survey

Geoscientific Characteristics of the Seafloor of the Southern Ocean of Japan Revealed by Japan's Continental Shelf Survey

Physiognomy and timing of metasomatism in the southern Vourinos ultramafic suite, NW Greece: a chronicle of consecutive episodes of melt extraction and stagnation in the Neotethyan lithospheric mantle

The Godzilla Megamullion, the largest oceanic core complex on the earth: a historical review

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