Lithospheric delamination is the foundering of dense lithosphere into less asthenosphere. The causes for this density inversion are thermal, compositional, and due to phase changes. For occur in specific, probably common, case where lithospheric mantle intrinsically than underlying asthenosphere compositional differences, a critical amount shortening required densifying effect cooler temperature counterbalance composition. Crustal thickening that results from may result crustal root that,...

Research Article| May 01, 1995 Magnesian andesite in the western Aleutian Komandorsky region: Implications for slab melting and processes mantle wedge G. M. Yogodzinski; Yogodzinski 1Institute Study of Continents Department Geological Sciences, Cornell University, Ithaca, New York 14850 Search other works by this author on: GSW Google Scholar R. W. Kay; Kay O. N. Volynets; Volynets 2Institute Volcanic Geology Geochemistry, Petropavlovsk, Kamchatka 683006, Russia A. V. Koloskov; Koloskov S....

The rare earth content of alkali-rich, silica-undersaturated basalts erupted onto oceanic and continental plates is consistent with their derivation by slight amounts partial melting hydrous garnet peridotite at the top asthenosphere, within low-velocity, low-Q zone mantle. earths are fractionated during retention heavy relative to light in clinopyroxene mantle residue. We conclude from a model that amount asthenosphere its clinopyroxene-garnet ratio increase decreasing thickness overlying...

A multicomponent melting-mixing model for the origin of volcanic arc basalt magmas implies signifi cant recycling K, Rb, Ba, and other elements in crust-upper mantel system. The accounts chemical differences alkali, alkaline earth, rare earth content between basalts a wide range oceanic intraplate types. In essence, are due to modification mantle peridotite by recycled continental components (derived from sediment sea water) at convergent plate margins. specific tested mass balance...

This work demonstrates superhydrophobic behavior on nanosecond laser patterned copper and brass surfaces. Compared with ultrafast systems previously used for such texturing, infrared fiber lasers offer a lower cost more robust system combined potentially much higher processing rates. The wettability of the textured surfaces develops from hydrophilicity to superhydrophobicity over time when exposed ambient conditions. change in wetting property is attributed partial deoxidation oxides surface...

This work reports the laser surface modification of 304S15 stainless steel to develop superhydrophobic properties and subsequent application for homogeneous spot deposition. Superhydrophobic surfaces, with steady contact angle ∼154° hysteresis ∼4°, are fabricated by direct texturing. In comparison common pico-/femto-second lasers employed this patterning, nanosecond fiber used in is more cost-effective, compact allows higher processing rates. The effect power scan line separation on...

Summary 1. AusRivAS (Australian River Assessment Scheme) models were developed, using macroinvertebrates as indicators, to assess the ecological condition of rivers in Western Australia part an Australia‐wide program. The based on data from 188 minimally disturbed reference sites and are similar RIVPACS used Britain. major habitats (macrophyte, channel) sampled separately collected identified family level. 2. Laboratory sorting preserved macroinvertebrate samples recovered about 90% families...

Xenolithic inclusions in calc-alkaline andesite from Mt. Moffett volcano, Adak Island, Aleutian arc, reveal a nearly continuous record of crystallization basaltic magmas the crust, and possibly upper mantle, arc. The is more detailed than that obtained study volcanic rocks Cumulate xenoliths form progressive series modal mineralogy ultramafic, hornblende-bearing olivine clinopyroxenite to both hornblende-free gabbros. cumulate hornblende gabbro are typical those found island arc andesites...

The tectonic position of Aleutian arc volcanic centers and their magmatic differentiation trends (calc‐alkaline or tholeiitic) appear to correlate. From 160°W 175°E, the volcanoes form four major segments that coincide with earthquake aftershock zones geographic features on both upper lower plates. tholeiitic are large, primarily basaltic occur between at end where magmas can more easily reach surface undergo shallow, closed system differentiation. calc‐alkaline smaller, andesitic in middle...

The crust in the central oceanic Aleutian arc has been formed by intrusion and extrusion of subduction-related magmas into onto pre-existing over at least past 50 m.y. Upper crustal rocks that have differentiated from a parental magma olivine tholeiite composition, residual crystals complementary to them, along with some early extrusive lavas, form lower crust. volumes upper calculated crystal fractionation models are consistent structure, velocity, density. Xenoliths ultramafic intermediate...

New chemical analyses of rocks from the Troodos ophiolite complex offer no clear evidence that it is a piece oceanic crust. Ratios selected nonlabile elements (REE, Zr, Ti) in lavas clearly distinguish them calc-alkaline evolved island arcs and basalts Hawaiian Icelandic type. However, these ratios are equivocal assigning to either ridge, small ocean basin, or young arc magma series. Gabbros quartz diorites plutonic appear be derived by low-pressure crystal settling magmas with same REE...

Deformed ultramafic xenoliths with basaltic salvages occur in a postglacial ejecta deposit from Adagdak volcano on Adak Island the central Aleutian Arc. These dunites, wehrlites, clinopyroxenites, and amphibolites are interpreted to be cumulates primitive arc magmas that formed magma chambers beneath crust-mantle boundary. The similar composition xenolith's host basalt (11.8% MgO). Trace element Nd Sr isotopic data consistent derivation of these same parent as other calc-alkaline volcanic...

Recent investigations of the lower continental crust have progressed along three relatively independent fronts: geophysics, field mapping, and study xenoliths brought to earth’s surface in volcanic kimberlitic eruptions. The general results these studies increased our appreciation scale crustal structural compositional complexity, but not point where we can construct an accurate cross section for even one locality. first part this review summarizes geophysical geological mapping studies,...

Research Article| January 01, 1976 Metalliferous deposits from the Apennine ophiolites: Mesozoic equivalents of modern oceanic spreading centers ENRICO BONATTI; BONATTI 1Lamont-Doherty Geological Observatory Columbia University, Palisades, New York 10964 Search for other works by this author on: GSW Google Scholar MARCO ZERBI; ZERBI 2Istituto di Petrografia, Università Parma, Italy ROBERT KAY; KAY HAROLD RYDELL 3Rosenstiel School Marine and Atmospheric Sciences, University Miami, Florida...

This work demonstrates a novel technique for fabricating surfaces with roughness and wettability gradients their subsequent applications chemical sensors. Surface on brass sheets are obtained directly by nanosecond laser texturing. When these structured exposed to air, decreases time (up 20 days) achieving both spatial temporal gradients. The responsive organic solvents. Contact angles of series dilute isopropanol solutions decay exponentially concentration. In particular, fall 132° in...

The evolution of the continents and continental crust is strongly dependent on trajectory sedimentary cover descending oceanic lithosphere at arc systems. Although direct calculations accretion are not reliable, indirect evidence suggests that most sediment either accreted or underplated (subcreted) to upper plate. This includes increased thickening accretionary prism beneath parts inner trench slope cannot be explained by deformation within protolith composition both in subophiolitic...