Distribution Of Calcium Carbonate Research Articles

Comment and Reply on "Distribution of calcium carbonate in desert soils: A model"

Comment and Reply on "Distribution of calcium carbonate in desert soils: A model"

Distribution of calcium carbonate in desert soils: A model

A model that describes the distribution of calcium carbonate in desert soils as a function of dust flux, time, climate, and other soil-forming factors shows which factors most strongly influence the accumulation of carbonate and can be used to evaluate carbonate-based soil age estimates or paleoclimatic reconstructions. Models for late Holocene soils have produced carbonate distributions that are very similar to those of well-dated soils in New Mexico and southern California. These results suggest that (1) present climate is a fair representation of late Holocene climate, (2) carbonate dust flux can be approximated by its Holocene rate, and (3) changes in climate and/or dust flux at the end of the Pleistocene effected profound and complex changes in soil carbonate distributions. Both higher carbonate dust flux and greater effective precipitation are required during the latest Pleistocene-early Holocene to explain carbonate distributions in latest Pleistocene soils. 21 refs., 4 figs., 1 tab.

Particle size distribution of agglomerated crystal product from a continuous crystallizer

Relationships have been derived for the particle size distribution in a continuous crystallizer operating in a steady-state regime, where agglomeration of the primarily generated crystalline particles takes place. The derivation was made for a constant kinetic coefficient of agglomeration (independent of the particle size) and for a negligible particle growth rate. The relatioships are used to interpret the particle size distribution of calcium carbonate precipitated from 0.2 mol dm-3 solutions of calcium chloride and sodium carbonate in a laboratory continuous crystallizer. Anomalous shapes of the size distributions of small particles frequently observed in continuous crystallizers are discussed in terms of the agglomeration phenomenon.

Quantitative ichnology of modern pelagic deposits in the abyssal Atlantic

Quantitative sedimentologic aspects of bioturbation were investigated in a series of deep-sea box cores, which were collected over a broad latitudinal range (35°N to 30°S) and bathymetric range (1.4 to 5.7 km) in the central Atlantic Ocean. All cores were thoroughly bioturbated, and numerous generations of burrowing could be discerned in many instances. Preservation of individually distinct burrows ranged from poor to excellent, and eight ichnogenera plus several unnamed biogenic structures were recognized. The distribution of calcium carbonate, organic carbon, selected species of planktic foraminifera and sediment grain size were examined in several cores. These measurements indicated that the surficial Mixed Layer, which ranged from 3 to 10 cm thick, was statistically more homogeneous than the underlying Transition Layer. This relationship is seen most clearly with respect to lateral and vertical variations in the calcium carbonate content of the cores. Bioturbation of abyssal pelagic deposits appears to be a two-phase process consisting of (a) homogenization of the upper few centimeters (i.e., the Mixed Layer) by shallow-burrowing meiofauna, and (b) heterogeneous mixing of the underlying strata (i.e., the Transition Layer) by relatively deep burrowers. The heterogeneously mixed Transition Layer becomes the preserved trace fossil record; under normal circumstances the homogenized Mixed Layer is not preserved.

Correction [to “‘Distribution of calcium carbonate in surface sediments of the Atlantic Ocean’”

Correction [to “‘Distribution of calcium carbonate in surface sediments of the Atlantic Ocean’”

Distribution of calcium carbonate in surface sediments of the Atlantic Ocean

The areal distribution of calcium carbonate in the surface sediments of the Atlantic Ocean and adjacent seas and oceans is mapped on the basis of over 1700 data points. The first-order relation of carbonate distribution to water depth is evident in both the areal distribution and the plots of carbonate versus depth for 11 areas of the Atlantic. Superimposed on this relation are significant variations in both the 100% and the 0% CaCO/sub 3/ depth intercepts, analogous to the (calcite) lysocline and the (calcite) carbonate compensation depth, respectively. Variations in these critical parameters between the 11 areas are related to the three rate processes which control carbonate distributions: surface productivity, dissolution, and dilution by noncarbonate biogenic and nonbiogenic sediment. The areal distribution of carbonate in surface sediments is compared with that in sediments deposited at the end of the last glacial epoch, 18,000 yr B.P., carbonate abundance was markedly lower.

Calcium carbonate distribution in the surface sediments of the Indian Ocean

A comprehensive calcium carbonate map for the Indian Ocean surface sediments has been prepared from the analysis of about 1200 samples. The percent carbonate distribution shows the well-known first-order correlation with depth and hence reflects the physiographic peculiarities of the Indian Ocean. Thus on topographic highs such as most of the mid-Indian ridge, Ninety East ridge, etc. the carbonate is high (>75%), whereas in deep areas such as the Wharton, Central Indian, Madagascar, and Somali basins the carbonate is low (<10%). Dilutions by terrigenous debris are marked in the Bay of Bengal and Arabian Sea adjacent to the Indian subcontinent and in the Mozambique Basin off southeast Africa. When the regions with significant terrigenous dilutions are excluded, certain systematic latitudinal variations in the carbonate critical depth (CCrD, depth below which less than 10% CaCO3 is present) and carbonate lysocline (depth at which a significant decrease in carbonate percent occurs) superimposed on the general first-order depth changes are evident. The CCrD is deepest in the equatorial region (10°N–10°S). Southward it gradually becomes shallow and reaches 4800–4600 m in the 20°S–30°S region and 4800 m in the 30°S–40°S region. It tends to deepen (∼4900 m) slightly in the 40°S–50°S region. The CCrD attains the shallowest level (3900 m) in the southernmost region (50°S–60°S) studied. The carbonate lysoclinal variation is in general opposite to that of the critical depths in the ocean north of 50°S and is the same as the critical depth in the 50°S–60°S region. These differences reflect the patterns of oceanic productivity and the dissolution effects of Antarctic Bottom Water. Low carbonate contents along with the presence of Antarctic diatoms and siliceous clay reported by Burckle et al. (1974) at 26°S–29°S and 60°E–64°E suggest a passage in the mid-Indian ridge in that area for the Antarctic Bottom Water flowing from the Crozet Basin to the Madagascar Basin.

CASPIAN SEDIMENTS-GEOLOGY OF THE SOUTHERN AND CENTRAL PARTS OF THE CASPIAN SEA

First discussed are the structural outline of the Caspian coasts and the several raised terraces. Submarine topography is very broadly oUtlined, as is the direction of currents (mostly counterclockwise in the central and southern CaSpian). Next, the authors consider the material contributed by rivers; the Volga brings in ¾ of the water, but the bulk of the sediment is contributed by the Terek and Kura which drain the Caucasus. There is a little quantitative data on the contribution of wind-blown material. The Caspian bottom sediments are mapped on the classification set up by Klenova (1931) which is based on the amount of material finer than 0.01 mm. Using this system, mud occupies the bulk of the Caspian floor grading to sand around the shoreline, with some carbonate mud along the shallow eastern part of the Caspian. In size analysis, each sample is divided into five fractions (over 1 mm, 1 to 0.1, 0.1 to 0.05, 0.05 to 0.01, and finer than 0.01 mm) and the results are plotted as histograms. Each main sediment type (e. g., muddy clay) is then divided into two or three subtypes based on intuitive examination of the histograms. The bulk of the paper is a description of the occurrences of the several sediment types. The authors next discuss briefly the regional distribution of calcium carbonate in the sediments. The Caspian muds contain pyrite, but the uppermost layer is oxidized and brownish, due to oxygenladen bottom currents. Several chemical analyses of the muds are presented. —R. L. Folk.

Soil Development in Relation to Loessial Deposition in Southeastern Minnesota

AbstractThe soils of southeastern Minnesota and adjacent areas are found to be developed mainly on loessial parent material of Wisconsin age. The origin, distribution, and some properties of the loess were studied. Loess deposition in southeastern Minnesota was found to have a general relationship to distribution of the major river valleys of the area. Measurements of loess thickness, determination of particle size analysis, and of calcium carbonate distribution provided evidence for this conclusion.The characteristics of two loess‐derived profiles developed under forest cover were studied. The profiles were selected to represent a range in degree of horizon development. The differences in profile development appear to be largely the result of weathering time.

Ecology of Some Arctic Foraminifera

An investigation of the Foraminifera in cores of the bottom sediments of the central Arctic Ocean indicates significant quantitative trends in this relatively uniform environment. Foraminiferal occurrence are compared with sediments, sea-floor topography, water depth, calcium carbonate distribution, organic C content of the sediments, temperature and salinity of the water, and associated organisms. A total of 105 species of Foraminifera, of which 20 were useful in establishing depth zones, were collected at depths between 433 and 2760 m. Five species and 1 variety are new. Faunal changes correspond generally to changes in slope. Application of the data suggests displacement of the sediments in parts of some cores.

Distribution of Calcium Carbonate in the Shelf Sediments Off East Coast of India

ABSTRACT Distribution of calcium carbonate in the sediments of the continental shelf off east coast of India from Ganges to Madras has been studied with reference to the distance from the coast, configuration of the shelf, and the silt-clay component of the sediments. The shelf is covered to a very large extent by terrigenous muds. Only on the outer shelf off Madras and Kakinada-Santapilli coast, do the sediments contain more than 50 percent calcium carbonate, and these are classified as carbonate sediments. The carbonate sediments are coarse in nature and exhibit their maximum spread off Visakhapatnam where the calcium carbonate increases from 5 percent near shore to 75-80 percent at 60 fathoms depth. Beyond the continental shelf it decreases to about 10 percent. On the basis of carbonate and silt-clay contents of the sediments in relation to the shelf topography and hydrodynamical conditions, the shelf, particularly off Visakhapatnam, is divided into three zones: (1) zone of active deposition of terrigenous material extending from coast to 33 fathoms, (2) zone of moderate deposition of terrigenous material existing between 33 and 52 fathoms, and (3) zone of slow or non-deposition outward of 52 fathoms depth. The sediments in the zone of slow deposition which is also the calcareous sediments zone, are believed to have been laid down when the sea level was relatively lower than now an to have not yet been covered by the present day deposition of terrigenous material.

Areal Variations of Calcium Carbonate and Heavy Minerals in Barataria Bay Sediments, Louisiana

ABSTRACT This paper is a report on a continuation study of the sediments of Barataria Bay. Former studies made of these Mississippi delta sediments included sediment size and organic carbon content. The present paper includes the calcium carbonate content and heavy mineral content. The analytical data are used to prepare maps of areal distribution of acid solubles and heavy minerals. The data are compared to show parallels existing between the areal distribution of calcium carbonate and heavy minerals. The heavy minerals, when separated from the sand fractions of the samples, show a distribution pattern in which high heavy mineral content parallels low calcium carbonate content. A comparison with earlier published data shows that high calcium carbonate is associated with fine sediments and high organic carbon, whereas high heavy mineral values are associated with coarser sediments and low organic carbon. The outstanding feature of the study is that the environmental patterns disclosed by heavy minerals and acid solubles agree well with the pattern, shown by size, sorting, and organic carbon.

Calcium-carbonate content of some California Mesozoic and Tertiary sediments

The calcium-carbonate content of approximately 8500 outcrop and well samples of Mesozoic and Tertiary sediments in California was determined in order to ascertain the extent to which the quantity of calcium carbonate in the sediments might be related to the conditions under which the sediments were deposited. In general, the different formations have an average carbonate content of approximately 5 per cent. The Miocene sediments, with an average of about 6 per cent, are the richest; the Eocene sediments, with an average of about 2 per cent, are the poorest. At least 25 per cent of the samples analyzed contain less than 1 per cent calcium carbonate, and nearly 50 per cent contain 3 per cent or less. Only 10 per cent of the sequences of sediments that were examined have an average carbonate content of more than 10 per cent, and very few have more than 20 per cent. The quantity of calcium carbonate in outcrop samples commonly is less than in well samples of corresponding age, owing to the effect of leaching. Much of the carbonate content of some of the Tertiary sediments apparently is due to the presence of Foraminifera. The areal distribution of calcium carbonate among sediments of similar stratigraphic age seems to show little relationship to the environmental conditions of deposition. The carbonate content of the Pliocene sediments in the Los Angeles basin, however, in general tends to increase away from probable position of the shore line at the time the sediments were deposited. Dolomite apparently is fairly common in the Jurassic and the Cretaceous sediments, not so common in the Eocene, Oligocene, and Miocene sediments, and rare in the Pliocene sediments.