Unusual calcite cementing of quartz grains on Chandeleur Island Beach, offshore Louisiana
A very unusual calcite cement was found in some beachchips from an unconsolidated beach surface of Chandeleur Island offshore approximately 35 nmi (65 km) south of Mississippi in the Gulf of Mexico. The beachchips are irregularly shaped and are well cemented by this unusual calcite. This calcite crystal structure has not been reported previously as existing in a marine environment. A similar cement has been found in freshwater lake beachrock and in some travertine samples. The calcite crystals are elongate parallel to the c-optic axis, and are composed of bunches of crystallite blades. The crystallite blades of each crystal bunch are pointed and are more bladed than freshwater cement crystals. The intercrystallite pore space contains no fine calcite silt as was observed in the lake samples. Fresh water provided by rainfall may be held in the pore spaces and bounded to the quartz-grain surfaces by ionic attraction. Marine spray above and saline water concentrated underneath from a sandwich effect at the micropore level, allowing rapid growth and precipitation of these very unusual calcite crystals in a single-phase low-salinity fluid.
- Research Organization:
- Sun Exploration Co., Dallas, TX
- OSTI ID:
- 6797744
- Report Number(s):
- CONF-8310301-
- Journal Information:
- Am. Assoc. Pet. Geol., Bull.; (United States), Vol. 67:9; Conference: American Association of Petroleum Geologists eastern section meeting, Carbondale, IL, USA, 3 Oct 1983
- Country of Publication:
- United States
- Language:
- English
Similar Records
Seawater fluid inclusions preserved within Cambrian-Ordovician marine cements indicate Cambrian-Ordovician seawater precipitated low-magnesium calcite
Marine low-magnesian calcite cement from periphery of Mururoa atoll
Related Subjects
CALCITE
CRYSTAL STRUCTURE
SEDIMENTS
CEMENTS
GULF OF MEXICO
ISLANDS
LOUISIANA
QUARTZ
SHORES
ALKALINE EARTH METAL COMPOUNDS
ATLANTIC OCEAN
BUILDING MATERIALS
CALCIUM CARBONATES
CALCIUM COMPOUNDS
CARBON COMPOUNDS
CARBONATE MINERALS
CARBONATES
CARIBBEAN SEA
CHALCOGENIDES
FEDERAL REGION VI
MATERIALS
MINERALS
NORTH AMERICA
OXIDE MINERALS
OXIDES
OXYGEN COMPOUNDS
SEAS
SILICON COMPOUNDS
SILICON OXIDES
SURFACE WATERS
USA
580100* - Geology & Hydrology- (-1989)