Coquina

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coquina

[kō′kē·nə]
(invertebrate zoology)
A small marine clam of the genus Donax.
(petrology)
A coarse-grained, porous, easily crumbled variety of limestone composed principally of mollusk shell and coral fragments cemented together as rock.

Coquina

 

limestone consisting primarily of the shells of marine animals or fragments of shells. Coquina usually forms in the littoral or sublittoral zones. Depending on the shells of which it is composed, coquina is subdivided into brachiopod, gastropod, ostracod, and other types. It corresponds to gravelpebble sediments in granulometric composition. Coquina has a very high porosity of 22–60 percent. Its specific gravity is 1,100-2,240 kg/m3, and its heat conductivity coefficient is 0.29-0.99 watt/(m-°K), or 0.25-0.85 kcal/(hr-m-°C). Its breaking point upon compression is 0.4-28 MN/m2 (4-280 kg/cm2).

Coquina is easily sawed, trimmed, and worked in various other ways. It is used extensively in construction as a wall and facing material; chipped rock and sand from coquina are used as a filler for light concrete. In addition, coquina is used in the production of lime and other binding materials. It is extracted in quarries.

Coquina is widespread in the Neogene beds of the southern USSR: in the Moldavian SSR, in the Crimean (the Mamai, Kutur-Kaia, Bagerovo, and Karalar deposits) and Odessa oblasts of the Ukrainian SSR, in the Azerbaijan SSR (the Apsheron Peninsula), and in the Turkmen SSR. Abroad, coquina is found in Poland and Rumania.

coquina

A soft limestone formed primarily of broken shells and coral; cut into blocks and used in construction.
References in periodicals archive ?
3), y consiste en coquinas y areniscas, tiene ~170 m de espesor (Figs.
Las coquinas se encuentran intercaladas principalmente con capas calcareas de color gris cremoso, en las que destacan cristales blanquecinos de calcita y fragmentos muy pequenos de conchas de color negro.
Por otro lado, la presencia de coquinas indica sepultamiento continuo, que impidio la destruccion subaerea de las comunidades de pelecipodos; solo el hundimiento relativamente rapido de la cuenca podria haber causado esto.
11); la parte media es una alternancia de coquinas de ostreidos de color negro con limolitas de color gris claro, que exhiben numerosas pistas de gusanos.
La Formacion Simon subyace concordantemente a la Formacion Otatera, de edad tardi-batoniana, consistente en ~170 m de coquinas de peleci-podos con intercalaciones de estratos calcareos de espatita; el ambiente deposicional inferido es neritico somero, con un componente subordinado de playa.
This unit concordantly underlies the Otatera Formation (Late Bathonian), consisting of ~170 m of pelecypod coquina with intercalations of spathitic limestone strata; it is regarded as shallow neritic deposit with a subordinate beach component.
1993), zonation (Turner & Belding 1957, Edgren 1959), and tidal migration in coquinas (Loesch 1957, Turner & Belding 1957, Edgren 1959, Mikkelsen 1981, Vega & Tunnel 1987).
When SL was compared between sites during a monthly sample collection, coquinas from BAS and RDB differed significantly (P < 0.
ABSTRACT Coquina clams (Donax variabilis) were sampled monthly at 2 sites in Pinellas County, Florida, to document recruitment and growth.
KEY WORDS: Donax variabilis, coquina, reproduction, life cycle, recruitment, biology
1992, The ecology of coquina clams Donax variabilis Say, 1822, and Donax parvula Philippi, 1849, on the east coast of Florida.
The section was sampled during fieldwork in 1987 as follows: pebbles from the basal conglomerate of the Ulgase Formation (N-62), lingulate brachiopod shells from the Ulgase Formation (N-63 and N-63A), and basal lingulate shell coquina of the Kallavere Formation (N-60).