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Topic: Carbonate rocks

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	Carbonates & Other Rocks
		Similarly carbonate rocks are composed of allochemical grains (grains produced by precipitation somewhere else and transported, usually short distances, to the depositional site), mud matrix, consisting of fine-grained carbonate minerals, and a crystalline cement of calcite (or dolomite) precipitated during diagenesis.
		Carbonate platforms are buildups of carbonate rocks in the deeper parts of the oceans on top of continental blocks left behind during continent - continent separation.
		Carbonate deposition can occur in non-marine lakes as a result of evaporation, in which case the carbonates are associated with other evaporite deposits, and as a result of organisms that remove CO from the water causing it to become oversaturated with respect to calcite.
	www.tulane.edu /~sanelson/geol212/carbonates.htm (3057 words)

	Our Dynamic Desert (Site not responding. Last check: 2007-09-18)
		Carbonate rocks originally form from limey sediments consisting of the calcareous skeletal remains of algae and invertebrate shell material or precipitates directly from agitated, warm seawater (as on a shallow continental shelf in a warm climate).
		The ancient carbonate rocks in the Mojave region are typically both dense and brittle and tends to be heavily fractured at the surface.
		Throughout the desert southwest, deep canyons carved into carbonate rock display collapse breccia, which are massive surficial deposits that consist of broken fragments of limestone and dolostone tightly cemented in a carbonate matrix.
	pubs.usgs.gov /of/2004/1007/carbonate.html (837 words)

	Colorado Rocks
		For example, igneous rocks formed at depth under high temperature (T) and pressure (P) in the absence of free oxygen and water are bound to change when brought to the surface to face chemical and mechanical weathering, erosion, transport, deposition and diagenesis.
		Rocks of the lower continental crust and the oceanic crust are almost always mafic.
		Clastic rocks can be categorized in any number of ways, but most classification schemes key on both grain size and composition, which together tell a lot about the source rock, the depositional environment, and all the steps in between.
	www.cliffshade.com /colorado/rocks.htm (9545 words)

	Occurrence & Mineralogy of Sedimentary Rocks
		Carbonate minerals, either precipitated directly or by organisms, make up most biochemical and chemical sedimentary rocks, but carbonates are also common in mudrocks and sandstones.
		In sediments or sedimentary rocks the porosity depends on grain size, the shapes of the grains, the degree of sorting, and the degree of cementation.
		An estimate of the porosity of the rock.
	www.tulane.edu /~sanelson/geol212/sedrxintro.htm (3373 words)

	[No title]
		Sodium carbonate dissolves quickly in rain water, so it is not surprising that there is virtually no record of ancient natrocarbonatites; the absence of sodium carbonate in intrusive carbonatites is explained by it’s removal by hydrothermal fluids during cooling and solidification.
		Cenomanian volcanic rocks, metamoprhic rocks (green schist, calc-silicate and amphibolite) and peridotites and gabbros of the Semail ophiolites.
		The silisification and carbonation of the serpentine in the Semail ophiolite seems to be of regional extents and extend for mor than 600 km from the southern to the northern parts of the nappe.
	www.angelfire.com /ms/snasir/CARB.htm (5550 words)

	Reservoir Rocks
		The physical composition of a rock and the textural properties (geometric properties such as the sizes and shapes of the constituent grains, the manner of their packing) are what is important when discussing reservoir rocks and not so much the age of the rock.
		Carbonates may also form as linear or continuous reef trends, as in the case of the Cretaceous reef structure in south Louisiana.
		Recent carbonate sediments have higher porosity values, but porosity is always reduced during burial and compaction which may reduce the thickness of a limestone bed by 25% under no more than a few hundred meters of overburden.
	www.leeric.lsu.edu /bgbb/4/rocks.html (2129 words)

	Carbonate rock - Wikipedia, the free encyclopedia
		Carbonate rocks are a class of sedimentary rocks composed primarily of carbonate minerals.
		Rare igneous carbonate rocks exist as intrusive carbonatites and even more rare volcanic carbonate lava.
		Karst topography and caves develop in carbonate rocks due to their solubility in dilute acidic groundwater.
	en.wikipedia.org /wiki/Carbonate_rocks (118 words)

	PSRD: Show Me the Carbonates on Mars
		Trace amounts of carbonates are widely distributed in the silicate-rich dust, but no evidence has been found in the TES data for widespread deposits of exposed carbonate rock.
		If the hypotheses for a ancient thick carbon dioxide atmosphere and water on Mars are true, including an ancient northern ocean, widespread smaller standing bodies of water, and outflow channels (as depicted in the graphic on the right), then one line of evidence would be the presence of carbonate rocks.
		It is possible that the small amounts of carbonate minerals in the dust are erosional remnants of ancient carbonate source rocks whose formation served as a buffer for atmospheric CO These carbonate rock layers may simply be hidden now beneath layers of the silicate-rich dust.
	www.psrd.hawaii.edu /Oct03/carbonatesMars.html (1772 words)

	Carbonate-rock aquifers (Site not responding. Last check: 2007-09-18)
		Solution openings in carbonate rocks range from small tubes and widened joints to caverns that may be tens of meters wide and hundreds to thousands of meters in length.
		Where they are saturated, carbonate rocks with well-connected networks of solution openings yield large amounts of water to wells that penetrate the openings, although the undissolved rock between the large openings may be almost impermeable.
		Some aquifers in carbonate rocks are overlain by confining units, and the aquifers extend into the subsurface beyond the areas shown on the map.
	capp.water.usgs.gov /aquiferBasics/carbrock.html (571 words)

	Astrobiology Magazine
		Carbonates are rocks and minerals which contain a molecule made of both carbon and oxygen known as CO Limestone is an example of a calcium carbonate, CaCO
		Carbonate rocks on Earth are formed in two ways: through a purely chemical process or via the action of living things.
		A rock from Mars, which was apparently ejected from the Red Planet by an asteroid impact millions of years ago, came to rest in Antarctica about 13,000 years ago, where it was found by scientists in 1984.
	www.astrobio.net /news/print.php?sid=124 (1212 words)

	The National Karst Map--Karst Maps
		The karstic carbonate rocks are Mississippian in age and include the Greenbrier limestone (West Virginia) and the Golconda, Ste.
		Cretaceous carbonate rocks of the Selma Group are extensive in central and western Alabama and northeastern Mississippi.
		The Silurian limestones and dolomites (Niagaran) of northwestern Ohio and adjacent Indiana are buried beneath glacial drift.
	www2.nature.nps.gov /nckri/map/maps/engineering_aspects/text.htm (5096 words)

	Women in Mining
		Carbonate: These cover about 10 to 15% and are made up chiefly of calcium carbonate and deposited by either inorganic or organic chemical processes.
		Approximately 90% of the carbonate rocks are from marine organisms.
		The oceanic plate is made of dense basaltic rock and the continental plate is made of lighter felsic igneous rock and sedimentary and metamorphic rocks.
	www.womeninmining.org /ROCKCYC.HTM (1274 words)

	Geology of NORM
		As with the igneous rocks, thorium and uranium tend to be minor or disseminated.
		Carbonate rocks are limestones or dolomites derived by chemical precipitation from water or by the buildup of shells, bones, and teeth of organisms.
		Therefore, potassium and thorium are usually of low concentrations in carbonate rocks, but uranium may be present because it may be fixed by reducing conditions in decaying organic matter where the rocks are deposited.
	www.tenorm.com /geo.htm (968 words)

	Carbonate Sedimentary Rock Classification
		Carbonate rock names (limestones and dolomites) consist of a conjunction of two names, one describing the ALLOCHEMS, the large pieces, the other describing the INTERSTITIAL MATERIAL.
		Allochems are equivalent to gravel, sand, lithics or feldspars in the siliciclastics.
		For example, a rock with fossil fragments embedded in micrite is called a "biomicrite".
	csmres.jmu.edu /geollab/Fichter/SedRx/Carbonate.html (811 words)

	Description of Carbonate Rocks
		Class I and II rocks are further subdivided by the relative percentage of the four different types of allochems and the size range of the allochems.
		In the pure sense of folk's classification all four rocks could exists however in practice since one is forced to attributes all microcrystalline to cryptocrystalline calcite grains under 2 mm in diameter to the pellets or pelloids the terms intrasparite and intramicrite are not used.
		Furthermore an oomicrite is itself a rare rock type as the process that cause the formation of ooids generally excludes the formation of a lime mud or microcrystalline to cryptocrystalline calcite matrix.
	people.uncw.edu /dockal/gly312/carbonate/carbonate.htm (2193 words)

	A Colour Atlas of Carbonate Sediments & Rocks Under the Microscope - Book Information (Site not responding. Last check: 2007-09-18)
		More than half of the world's petroleum is to be found in carbonate rocks, for example in the Middle East, the former USSR and in North America.
		These rocks show a bewildering diversity of grains and textures, due in part to the wealth of different fossil organisms which have contributed to carbonate sedimentation, and in part to a wide variety of diagenetic processes which can radically modify textures and obscure the depositional fabric.
		Careful petrographic study with a polarising microscope is a key element of any study of carbonate sediments, as a companion to field or core logging, and as a necessary precursor to geochemical analysis.
	www.blackwellpublishing.com /book.asp?ref=1874545847 (208 words)

	November 2002 AGGMAN Geology (Site not responding. Last check: 2007-09-18)
		These carbonate rocks and products derived from them are used as aggregates, cement, fluxes, glass raw material, refractories, fillers, abrasives, soil conditioners, environmental applications, ingredients in a host of consumer products, and much, much more.
		Carbonate rocks form about 15 percent of the earth’s sedimentary crust and occur in rock formations that range in age from the youngest (Holocene) to the most ancient (Precambrian).
		Because the oceans have remained for millions of years, the life forms in the oceans were able to remove the original huge mass of carbon dioxide gas from the atmosphere by incorporating it into limestone and other carbonate rocks.
	www.aggman.com /1102_pages/1102carved.html (916 words)

	Products: Calcium Carbonate - [Omya New Zealand]
		If igneous rocks are attacked during this process, the decomposition and transformation of minerals containing calcium, such as augite and hornblende, may yield juvenile i.e ‘new’ calcium carbonate which is brought into the cycle.
		The solubility of carbonates in water depends largely on the carbon dioxide content of the water, this being essential for the formation of the bicarbonate.
		Unstable carbonates, such as aragonite, magnesia-calcite and vaterite present in the sediment, are dissolved and redeposited in pore spaces as calcite or dolomite.
	www.omya.co.nz /products_cc_geology_cycle.html (1032 words)

	Oil Recovery In Carbonate Rocks
		Geologists have defined carbonate pore classes based on sedimentology, thin sections and porosity-permeability relationships, but the question remains as to whether these pore classes are valid when considering oil recovery by waterflooding.
		Results: In addition to separating carbonate core material into different pore classes based on thin sections and porosity-permeability relationships, we have used single-phase tracer dispersion tests as a means of evaluating whether there are systematic differences in the flow properties between different pore classes.
		In addition, we find that low permeable carbonate may still give high oil recovery efficiency if the fraction of inaccessible and dead-end pores, as evaluated from tracer dispersion characteristics, is low.
	www.uib.no /cipr/research/OilRecoveryInCarbonateRocks.htm (431 words)

	USC Sequence Stratigraphy - Carbonate Petrology (Site not responding. Last check: 2007-09-18)
		Here, as in the version that Dhakilallah Al-Adwani produced, the text of the outlined exercises was written by Christopher Kendall and is based on the text of the carbonate petrography exercises that were developed by Robert Folk of the University of Texas at Austin.
		Some photomicrographs are of chemical rocks of various compositions that are often found with carbonates.
		If this carbonate petrography section of the USC web site is being used by those who have no access to the carbonate thin sections of the University of South Carolina Department of Geology, they can still use the photomicrographs and the text that accompanies them to better understand how to describe carbonate thin sections.
	strata.geol.sc.edu /thinsections/carbonate_petrology.html (377 words)

	GEOL 8200: Carbonate Petrology (Site not responding. Last check: 2007-09-18)
		GEOL 8200 is a carbonate petrology course taught by Bruce Railsback at the University of Georgia.
		Course Objectives: To train students as competent carbonate petrographers (a true carbonate petrologist also needs analytical tools too), to familiarize students with the literature on carbonate rocks, to show students the principal problems of carbonate petrology, and to develop writing skills for the geosciences.
		The first three labs are intended to familiarize students with components of carbonate rocks, and the first one just explains the ideas needed to work on Labs 2 and 3.
	www.gly.uga.edu /railsback/8200main.html (881 words)

	Gregor Baechle
		Carbonates II Seminar, London Petrophysical Society, Dez 19th 2001, Burlington House, London, England.
		Baechle, G.T., Weger R.J., Eberli, G.P., and Massaferro, J.-L. The role of macroporosity and microporosity in constraining uncertainties and in relating velocity to permeability in carbonate rocks.
		Effects of pore structure on permeability and sonic velocity in carbonate reservoir rocks (2002).
	mgg.rsmas.miami.edu /students/greg (616 words)

	The Carbonate System (Site not responding. Last check: 2007-09-18)
		Carbonates play important role in neutralization of strong bases and acids.
		Carbon dioxide from the atmosphere is dissolved or volatilized from water.
		Bicarbonate donates the last proton to form carbonate, CO The dissolution/volatilization of carbonic acid is a very slow reaction as compared to the acid base reactions involved in proton transfer
	www.swbic.org /education/env-engr/carbonate/carbonate.html (481 words)

	Wiley::A Color Atlas of Carbonate Sediments and Rocks Under the Microscope (Site not responding. Last check: 2007-09-18)
		More than half of the world’s petroleum is found in carbonate rocks — for example, in the Middle East, the former USSR and in North America.
		These rocks show a bewildering diversity of grains and textures, due in part to the wealth of different fossil organisms that have contributed to carbonate sedimentation, and in part to a wide variety of diagenetic processes that can radically modify textures and obscure the depositional fabric.
		Careful petrographic study with a polarising microscope is a key element of any study of carbonate sediments — as a companion to field or core logging and as a necessary precursor to geochemical analysis.
	www.wiley.com /WileyCDA/WileyTitle/productCd-047023749X.html (335 words)

	Sedimentary Rocks
		Terrigenous sedimentary rocks are derived from the weathering of pre-existing rocks, whch have been transported to the depositional basin.
		These chemicals may be removed from seawater and made into rocks by chemical processes, or with the assistance of biological processes (such as shell growth).
		Carbonates - The carbonate sedimentary rocks are formed through both chemical and biochemical processes.
	gpc.edu /~pgore/geology/geo101/sedrx.htm (688 words)

	Compaction, dilatancy, and failure in porous carbonate rocks
		In this study we acquire new mechanical data on the Indiana and Tavel limestones, which show that the phenomenology of dilatant and compactant failure in these carbonate rocks is similar to that of the more compact Solnhofen limestone as well as sandstones.
		Previously, two micromechanical models were used to interpret mechanical behavior of Solnhofen limestone: viewing cataclasis and crystal plasticity as two end-members of inelastic deformation mechanisms, the wing crack and plastic pore collapse models were applied to brittle and ductile failure, respectively.
		Synthesizing published data for carbonate rocks with porosities between 3% and 45%, we investigate to what extent the same micromechanisms may be active at higher porosity.
	www.agu.org /pubs/crossref/2004/2003JB002508.shtml (365 words)

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