Calcite dolomite thermometry pdf

Comparative thermometry was undertaken with widely used calibrations for the systems garnetbiotite, calcitedolomite, and calcitegraphite. Reaction mechanism for the replacement of calcite by. Pdf comparison of garnetbiotite, calcitegraphite, and. Forward modeling of the effects of mixed volatile reaction, volume diffusion, and formation of submicroscopic exsolution lamellae on calcitedolomite thermometry thomas muller,1, lukas p. Drscussron the rray method has the advatage of giving results proportional to the total amount of material present having the calcite and dolomite structure types. The temperature dependence of carbon isotopic fractionations between calcite and graphite, and between dolomite and graphite are calibrated by the.

Peak metamorphic temperatures can also be estimated using the distribution of mg between calcite and dolomite rathmell et al. Dolomite is ananhydrous carbonate mineralcomposed of magnesiumcarbonate, calcium ideally camgco 3 2. Calcite caco3 c 20012005 mineral data publishing, version 1 crystal data. Application of clumped isotope thermometry to archean. Ferroan calcite cements contain microsized dolomite inclusions mdis. Calcitegraphite thermometry of the franklin marble, new. Dolomite camgco32 c 20012005 mineral data publishing, version 1 crystal data. Dolomite formed at 4272 911 c 2 standard deviations, sd from fluid with. Small quantities of the carbonates were allowed to equilibrate with large volumes of aqueous solutions, permitting the approach of phase boundaries from two directions. Application of infrared thermometry and ultrasonic. Dolomite has r3 symmetry, lower than the caco3 r3c symmetry of calcite primarily due to camg ordering. The exact proportion of each carbonate phase was determined in each sample using the yields of calcite and dolomite from offline extractions, assuming that only 90% of all calcite present is reacted in the first step and 70% of all dolomite in the second see section 4. Along with calcite and aragonite, dolomite makes up approximately 2 percent of the earths crust. Because nearly all samples in this study have less than 5% dolomite, any potential contribution of dolomite to the co2 evolved from calcite during the first two hours is negligible.

Calcite and magnesite decompose at different temperatures, a stepwise decomposition permits the selective calcination in which magnesite is completely decomposed without decomposing calcite. Dec 01, 2005 this study presents calcitegraphite carbon isotope fractionations for 32 samples from marble in the northern elzevir terrane of the central metasedimentary belt, grenville province, southern ontario, canada. Calcite dolomite geothermometry has been used to determine the equilibrium temperature of the bayan obo carbonatite. Calcite and horn blende are intermediate between quartz and the micas. Ontario, canada article pdf available in contributions to mineralogy and petrology 42.

Porosity logging the porosity of a zone can be estimated either from a single porosity log sonic, density, neutron, or magnetic resonance log or a combination of porosity logs, in order to correct for variable lithology effects in complex reservoirs. Dolomite, a related mineral, is made of magnesium carbonate mgco3. I observe reasonable agreement between these predictions and available experimental determinations e. The results show that there are large variations within single samples, and, insofar as any thermal gradient can be detected, it. Coexisting calcitedolomite and graphite gave carbon isotope fractionation between 1. The marble has undergone two metamorphic episodes, early contact metamorphism and. Application of calcitegraphite carbon isotope thermometry. Cathodoluminescence petrography shows that this group of calcite grains formed later as it occurs pre. Oxygen isotope composition of the phanerozoic ocean and a possible solution to the dolomite problem uri ryba,1 and john m. Application of calcitegraphite and garnetbiotite systems may yield temperatures up to 70 c higher than calcitedolomite in amphibolite facies rocks. Crystals typically combinations of 1011 and 1120, tabular on 0001, many minor forms, may exhibit curved faces, to 20 cm.

In the carbonates, mineral mixtures are primarily drawn from calcite, dolomite, and. Xray diffraction technique indicated the calcites mgco3 content up to 7. Highmagnesium calcite also has r3c symmetry and differs from dolomite. The dolomite at east ore body and the calcite dolomite dyke at. Calibration of the dolomite clumped isotope thermometer from. Almost all dolomites are believed to be produced by recrystallization of preexisting limestones, although the exact details of this dolomitization process. Two distinct carbonate platforms exist on the plateau. Sedimentary rock limestones and dolomites britannica. Constraints on the conditions of metamorphism of the llano uplift, central texas, u. Pdf mineralogy, nucleation and growth of dolomite in the. Abstract dolomite or calcite, quartz and kaolinite in various proportions were reacted at 250300 temperatures and pressures up to 90 bars in a hydrous environment.

The results show that there are large variations within single samples, and. Recommended method for semiquantitative measurement of. The best way to tell one from the other is the acid test. Carbon isotopic thermometry calibrated by dolomite calcite. Clumped isotope thermometry of calcite and dolomite in a. Clumped isotope thermometry of calcite and dolomite in a contact. Calcitedolomite geothermometry of bayan obo carbonatites. In addition to a paucity of data for dolomite, the published calibration results for calcite diverge. View enhanced pdf access article on wiley online library html view download pdf for offline viewing. Reactions 31 34 have been written as oneway processes 7 resulting. Negative evidence from the marmorilik formation, west greenland. Application of calcitegraphite carbon isotope thermometry in. Dolomite calcite stable isotope exchange reactions.

Experimental data indicate that the stability field of calcite narrows toward. The carbonate peak in the raman spectrum of calcite at. Calcitedolomitemagnesite stability relations in solutions. These results are compared with temperatures calculated by calcitedolomite thermometry 15 samples, garnetbiotite thermometry four samples and garnethornblende thermometry. Comparison of clumped isotope signatures of dolomite cements.

Pdf comparison of garnetbiotite, calcitegraphite, and calcite. Forward modeling of the effects of mixed volatile reaction. Petrographic and scanning electron microscope analysis of dolomite samples indicated different grain sizes. At low temperatures the bonds between rare, heavy c and 18 o isotopes are thermodynamically favored, and thus at equilibrium they are present in higher than random abundances. The term is also used for a sedimentary carbonate rock composed mostly of the mineral dolomite. Coexisting calcite dolomite and graphite gave carbon isotope fractionation between 1.

Calcite grains from 19 composite dolomitecalcite marble samples from the marmorilik formation, west greenland, have been analysed for ca, mg, and fe with the results show that there are large variations within single samples, and, insofar as any thermal gradient can be detected, it is the opposite of that indicated by mineral parageneses. Comparative thermometry was undertaken with widely used calibrations for the systems garnetbiotite, calcite dolomite, and calcite graphite. Much debate exists on the extent to which early dolomites recrystallize and preserve the signature of their primary diagenetic setting. Comparison of clumped isotope signatures of dolomite. Many of the early applications of the d 47 paleothermometer. Abstract clumped isotope thermometry of carbonates in the carbonaceous chondrites cm, ci, cr and tagish lake demonstrates that aqueous alteration of their parent bodies occurred from 31 to 71c and involved reaction with fluids having. Metamorphic temperature investigation of coexisting. Calcite grains from 19 composite dolomite calcite marble samples from the marmorilik formation, west greenland, have been analysed for ca, mg, and fe with the microprobe in order to estimate metamorphic temperatures using the calcite dolomite solvus geothermometer. Comparison of clumped isotope signatures of dolomite cements to. Calcite dolomite thermometry peak metamorphic temperatures can also be estimated using the distribution of mg between calcite and dolomite rathmell et al. Calibration of the dolomite clumped isotope thermometer from 25 to 350c, and implications for a universal calibration for all ca, mg, feco 3 carbonates magali bonifacie 1, 2, 3, damien calmels 1, john m.

Multiplephase clumped isotope measurements are complemented by bulk. Magnesium partitioning between calcite and dolomite is a function of temperature along the calcite dolomite miscibility gap letargo et al. Both have the same hardness h 3, the same rhombohedral cleavage, and are found in identical geologic settings. Reaction mechanism for the replacement of calcite by dolomite. Preparation of high purity magnesium oxide from dolomite. This makes the dolomite a reservoir rock and a target of oil and gas drilling.

The northern marion platform nmp is a lowangle ramp attached to the australian mainland whereas the southern marion platform smp is an isolated and asymmetric rimmed. The difference between extreme values of fi in the rock, normalized with. Calcite compositions were measured by emp in six samples of the periclase skarn. Elemental and isotopic compositions of mdis are virtually. This is a pdf file of an unedited manuscript that has been accepted for. The bulk of the dolomite constitutes dolostone formations that occur as thick units of great areal extent in. An alternative name sometimes used for the dolomitic rock type is dolostone. Dolomite camgco 3 2 can be distinguished from calcite caco 3 using raman spectroscopy. Limestones and dolomites are collectively referred to as carbonates because they consist predominantly of the carbonate minerals calcite caco3 and dolomite camgco32. Wellformed crystals are common, 1011, 21, thin to thick tabular 0001, with combinations of over forms noted, to 7 m. This specimen features a group of marcasiteincluded, yellow calcite crystals that have formed over a bit of dolostone matrix.

During the conversion of calcite to dolomite, a volume reduction occurs. Thermobarometry is the quantitative determination of the temperature and pressure at which a metamorphic or igneous rock reached chemical equilibrium. Carbonate clumped isotope thermometry is based on the temperaturedependent formation of c 18 o 16 o 2 2. Calcite the main mineral in limestone is made of calcium carbonate caco3. The temperature of formation of replacement dolomite and. Clumped isotope compositions of slowlycooled calcite and dolomite. Magnesium partitioning between calcite and dolomite is a function of temperature along the calcitedolomite miscibility gap letargo et al. The carbonate peak in calcite at 1086 cm1 is shifted to 1099 cm1 in dolomite. Exsolution of dolomite and application of calcitedolomite solvus.

This can produce pore spaces in the rock that can be filled with oil or natural gas that migrate in as they are released from other rock units. Calcite and dolomite from marble have an average d c of pdb and a more limited range than other mesoproterozoic0. Calcite in met 01070 falls into two isotopic groups, one group has. Eilera adivision of geological and planetary sciences, california institute of technology, pasadena, ca 91125 edited by donald e. Application of infrared thermometry and ultrasonic velocity for the investigation of the building materials of historic monuments of dion, greece papanikolaou e. However, calcite graphite thermometry occasionally yields low temperatures due to lack of equilibration of anomalously light graphite. Ccdol thermometry indicates temperatures between 544c and 591c. The elzevir terrane of the grenville orogen in southern ontario contains metapelites and abundant graphitic marbles that were regionally metamorphosed from the upper greenschist to upper amphibolite facies. Calibration of the dolomite clumped isotope thermometer. Metamorphic temperature investigation of coexisting calcite. Two types of marbles, that is, calcite dolomite marble and quartzbearing calcite dolomite marble were selected.

There is no correlation between calculated temperatures and the distance from the igneous contact. Camg interdiffusion in synthetic polycrystalline dolomitecalcite. Carbonates 63 any process that increases the amount of c02 available to the solution makes more cac0 3 dissolve. For example, many of the early paleozoic carbonate buildups of the wabash platform in the american midwest are now entirely dolomitized, but the pipe creek junior quarry in central indiana exposes a unique bioherm with only minor dolomite. Sedimentary rock sedimentary rock limestones and dolomites. Less than 1% of dolomite reacts in the first two hours, 30% over the first 24 hours at 25 c, and 70% in the following 24 hours at 50 c. These values, if in equilibrium, correspond to metamorphic temperatures between 1100 and 640. The stability relations of calcite, dolomite, and magnesite in aqueous cacl2mgcl2co2 solutions have been determined between 275 and 420c. Of all published articles, the following were the most read within the past 12 months. Comparison of garnetbiotite, calcitegraphite, and calcite. At low temperatures the bonds between rare, heavy c and 18o isotopes are thermodynamically favored, and thus at equilibrium they are present in higher than random abundances.

The interface between these domains is the location of the 330. Formation of dolomite at 4080 c in the latemar carbonate. Diagenetic and mineralogical effects in clumped isotope. Estimated carbonate formation temperatures decrease in. Calcite the main mineral in limestone is made of calcium. It is even possible to differentiate different crystalline forms of calcium carbonate such as calcite and aragonite. Previous empirical calibration of the calcitegraphite thermometer agrees very well with calcitedolomite, garnetbiotite and garnethornblende thermometry, whereas, theoretical calibrations compare less well with the independent thermometry. These studies concluded that the calcite dolomite thermometer recorded peak metamorphic conditions. Dolomite, type of limestone, the carbonate fraction of which is dominated by the mineral dolomite, calcium magnesium carbonate camgco 3 2 general considerations. These isotopic exchange thermometers are largely consistent with peak temperatures in all samples within 4 km of the contact, indicating that metamorphic recrystallization can occur even in samples too lowgrade to produce.

Crystal size distribution of periclase in contact metamorphic. Because clumped isotope compositions are sensitive to the details of tt path within these intervals, measurements of the. Comparison of garnetbiotite, calcitegraphite, and calcitedolomite thermometry in the grenville orogen. Dolomite also serves as an oil and gas reservoir rock. Previous empirical calibration of the calcite graphite thermometer agrees very well with calcite dolomite, garnetbiotite and garnethornblende thermometry, whereas, theoretical calibrations compare less well with the independent thermometry. Magnesium oxide is then separated physically from the calcined dolomite by sieving or air separation. Dolomite crystals also line or fill pores in carbonate limestone and dolostone rocks or in hydrothermal veins. Reactions which approached completion produced talc, calcite, montmorillonite, anorthite both metastable hexagonal and stable. The term classical thermobarometry refers to methods for calculating the pt conditions of a specific chemical. The temperature dependence of carbon isotopic fractionations between calcite and graphite, and between dolomite and graphite are calibrated by the calcite dolomite solvus geothermometry using marbles collected from the contact metamorphic aureole in the kasuga area, central japan.

Oxygen isotope composition of the phanerozoic ocean and a. As calcite dissolves more easily than dolomite, such calcite fossils can later be dissolved to leave fossil molds in the dolostone rock. Abatraetthe temperature dependence of carbon isotopic fractionations between calcite and graphite, and between dolomite and graphite are calibrated by the. The marion plateau is a 77,000km 2 wide basement block lying on the passive continental margin of northeastern australia davies et al. An exceptional view of geological materials with raman.

Here, we combine clumped isotopes thermometry with xray diffraction and thin section petrography to study dolomite recrystallization under shallow burial dolomite samples from two miocene carbonate platforms. Calcitedolomite cycles in the neoproterozoic cap carbonate. In this study, it is shown that calcitedolomite solvus thermometry can be applied to calcite inclusions in forsterite and spinel for the estimation. These results are compared with temperatures calculated by calcite dolomite thermometry 15 samples, garnetbiotite thermometry four samples and garnethornblende thermometry three samples. Calcitegraphite isotope thermometry in amphibolite facies. Carbon isotopic thermometry calibrated by dolomitecalcite solvus. What happens if a geologist drips a small amount of vinegar acetic acid onto a sample of dolomite. A sweet calcite with marcasite inclusions on matrix from a herkimer diamond quartz pocket at the benchmark quarry, in st.