Pillow Lava


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pillow lava

[′pil·ō ‚läv·ə]
(geology)
Any lava characterized by pillow structure and presumed to have formed in a subaqueous environment. Also known as ellipsoidal lava.

Pillow Lava

 

lava that has been extruded into water. Flows appear as series of spheres 1-5 m in diameter, which are composed of glass along the margins and crystalline rock in the center.


Pillow Lava

 

basic (andesitic or basaltic) lava extruded into water and consisting of a series of spheres that fit closely upon one another. A glassy hardening zone is observed on the edges of each sphere; in the center of some large spheres, divergent part ing is observed. Pillow lava is found in volcanic oceanic beds in association with keratophyres and spilites. It also occurs as part of ophiolitic complexes.

References in periodicals archive ?
* Facies de pillow lavas: Niveles de lavas basalticas que se disponen en una sucesion estratocreciente de lavas groseramente cilindricas; presentan secciones transversales semicirculares que poseen una estructura interna concentrica y/o radial; entre las almohadillas se observa la ocurrencia de drusas (Figura No.
* Facies de brechas y pillow lavas: Secuencias transicionales entre las facies de pillow lavas y la facies de brechas; corresponden al autobrechamiento de las lavas hialoclastitas y/o a pillow aislado.
La relacion inversa de las facies de pillow lavas, con respecto a las brechas, indica un aumento progresivo de la actividad volcanica; al mismo tiempo, los sedimentos estratificados entre las pillow lavas indican que esta actividad no fue constante.
With rare exception, dredge hauls recovered young glassy pillow lavas with no ferromanganese crust or sediment cover (Cousens 1982).
A 1994 cruise (PGC94-04) recovered glassy pillow lavas from a flow just south of the 1970 dredge on the northwestern knoll.
The young rocks are pillow lavas, created when molten rock comes in contact with cold water.
The pillow lavas have often Basaltic composition and have gone under spilitisation phenomenon process, and minerals like Albite, chlorite, Calcite, Zeolite, Serpentine, etc.
Alison Lea-Wilson, Angleseybased chairman of Tourism Partnership North Wales, said the island's geology was accessible to non-experts through features such as the cliffs of South Stack and the Precambrian pillow lavas of Llanddwyn Island.
While most of these drill holes produced "normal" sections of extrusive basalts occurring as pillow lavas and flows, a few holes crossed peridotites or gabbros, either just beneath the sediment cover or within the lava sequence.
On three previous legs, researchers had drilled through sediments and pillow lavas and into the sheeted-dikes layer, to a total depth of 1,350 meters below the seafloor.
In Archean rocks, scientists had previously found only sediments and pillow lavas, leading some to suggest that these rocks were created not by seafloor spreading in deep oceans but in the shallow seas that formed over continents as they were rifted apart.