ISSN:
1365-3091
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Geosciences
Notes:
Cemented layers in the shallow lagoonal, intertidal, and supratidal sediments surrounding the Qatar Peninsula, Persian Gulf, contain high-magnesian calcite and aragonite cements. The magnesian calcite appears to occur both as a primary precipitate and as a replacement of aragonite. These cements are believed to be forming today from sea-derived waters. Radiocarbon dating sets an upper age limit of about 4,500 years.Two major types of cemented layer can be distinguished: beachrocks form variably cemented units about 1 m thick at the surface of freely draining exposed beaches: cemented sheets a few cm thick form beneath the surface of broad intertidal sand flats by the growth, hardening, and coalescence of small friable lumps near low-tide level. Replacement of aragonite matrix, druse, and pellets by microcrystalline magnesian calcite is accomplished by dissolution and reprecipitation; detail is obliterated but the gross features of the original fabric are preserved. The process helps to explain the crystal fabrics of many older limestones.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1365-3091.1969.tb00165.x
Permalink