Reconstruction Of Mass Balance Research Articles

Mass-balance reconstruction of a modern Vertisol: implications for interpreting the geochemistry and burial alteration of paleo-Vertisols

Utilizing identical sampling and analytical techniques, the morphological and chemical characteristics of a modern Vertisol (Houston Black series, central Texas) can be directly compared with an Upper Mississippian paleo-Vertisol from the Appalachian basin (Pennington Formation, east-central Tennessee). Mass-balance reconstructions suggest retention of primary pedochemical patterns in the paleo-Vertisol, including patterns of soil volume change (strain) and transport functions (translocations) of many major and trace elements. Retention of primary pedochemical patterns suggests that Vertisols constitute nearly closed systems during burial diagenesis. Chemical and mineralogical changes associated with burial diagenesis of the paleo-Vertisol include oxidation of organic carbon (OC), illitization of smectites, dehydration and recrystallization of Fe–Mn oxyhydroxides, and dolomitization of pedogenic calcite. Significant differences in the chemical behavior of gilgai microhigh and microlow pedons in modern Vertisols have implications for interpretation of geochemical data obtained from paleo-Vertisols. Overall wetter soil conditions and variable redox potential under gilgai microlows promote greater depths of leaching and mobility of redox-sensitive trace elements, including Co, Cr, Cu, Mn, Ni, and V. Gilgai microhighs behave as evaporative “wicks” that draw moisture and soluble phases towards the soil surface, resulting in precipitation of metal hydrosylate complexes and sulfates (gypsum) at the capillary fringe and shallower depths of leaching and fixation of trace elements. Paleoprecipitation estimates from paleosols, based on the depth to the top of the pedogenic carbonate horizon, should therefore utilize field, petrographic and geochemical data for characterizing maximum depths of leaching, loss or gain of exchangeable bases, and calcification, rather than relying solely upon field data.

Photogrammetric reconstruction of glacier mass balance using a kinematic ice-flow model: a 20 year time series on Grubengletscher, Swiss Alps

AbstractThe kinematic boundary condition at the glacier surface can be used to provide glacier mass balance at individual points if changes in surface elevation, horizontal and vertical surface velocities and surface slope are known. Vertical ice velocity can in turn be estimated from basal slope, basal ice velocity and surface strain. This relation is applied to reconstruct a 20 year mass-balance curve of Grubengletscher, Swiss Alps, largely using repeated aerial photogrammetry, with only a minimum of fieldwork For individual years the mass-balance distribution on the glacier tongue was modelled with an accuracy of about ±0.9 m a"1. Ice-mechanical assumptions and errors in glacier bed geometry markedly affect discrete mass-balance patterns but are largely eliminated in the calculation of year-to-year mass-balance changes The resulting 1973–92 curve for the Grubengletscher tongue shows reasonable consistency with meteorological data and other glaciologically derived mass-balance series. Large changes in measured ice speed on the glacier tongue (±50%) significantly governed the long-term variability of ice thickness over the observational period.

Measurement and estimative models of glacier mass balance in china

Attributed to high altitude and inland location, the glaciers in China are characterized by very low temperature. The non‐negligible contribution of up to 25% of superimposed ice to the net balance has been taken into account in the mass budget calculation. So too has the internal the accumulation in the infiltration zone of the accumulation area.The prevailing monsoon climate delivers most of the annual precipitation over glaciated areas of China in the summer, making the major accumulation on those glaciers coincide with the ablation period. Therefore, the annual mass balance should be calculated neither by giving the place of annual accumulation to winter balance, nor annual ablation to summer balance. Rather, it is better done by net accumulation and net ablation during the year. In order to get the annual accumulation and the annual ablation on a glacier, the summer precipitation should be measured at the same time.Frequent snowfall in the summer season results in intensive fluctuation of surface albedo. This means that, for lack of data on the extremes of ablation, reconstruction of mass balance is unsatisfactory when based on the relationships of accumulation and ablation to precipitation and temperature. The establishment of models, either on the relationship of multi‐year mass balance to the equilibrium line and the mass balance gradient of a glacier in steady‐state, or on the maximum entropy principle and the hydrometeorological data, helps to estimate the multi‐year mass balance of the glacierized area in a mountain range or drainage basin.

Altitudinal gradient of mass-balance sensitivity to climatic change from 18 years of observations on glacier d’Argentière, France

AbstractAssessment of the contribution of small glaciers to sea-level rise or the reconstruction of past glacial mass balance requires knowledge of mass-balance sensitivity to climatic variations. The aim of this paper is to clarify this relation. The mass-balance fluctuations analyzed from measurements on glacier d’Argentière, Mont Blanc massif, France, between 1850 and 2700 m a.s.l. were compared with climatic variations at a nearby meteorological station. Statistical study of the data shows that: (1) the annual mass-balance fluctuations are dependent on elevation, and (2) the mass-balance sensitivity to temperature decreases with altitude and diverges from current model results. Consequences of a temperature variation of 1°C for global volume variations are significant. A simple calculation on glacier des Bossons, Mont Blanc massif, France, shows that the sensitivity from the model can lead to volume variations twice as high as results compatible with our observations.

Altitudinal gradient of mass-balance sensitivity to climatic change from 18 years of observations on glacier d’Argentière, France

AbstractAssessment of the contribution of small glaciers to sea-level rise or the reconstruction of past glacial mass balance requires knowledge of mass-balance sensitivity to climatic variations. The aim of this paper is to clarify this relation. The mass-balance fluctuations analyzed from measurements on glacier d’Argentière, Mont Blanc massif, France, between 1850 and 2700 m a.s.l. were compared with climatic variations at a nearby meteorological station. Statistical study of the data shows that: (1) the annual mass-balance fluctuations are dependent on elevation, and (2) the mass-balance sensitivity to temperature decreases with altitude and diverges from current model results. Consequences of a temperature variation of 1°C for global volume variations are significant. A simple calculation on glacier des Bossons, Mont Blanc massif, France, shows that the sensitivity from the model can lead to volume variations twice as high as results compatible with our observations.

Meteorological controls on glacier mass balance: empirical relations suggested by measurements on glacier de Sarennes, France

AbstractGlacial mass-balance reconstruction for a long-term time-scale requires knowledge of the relation between climate change and mass-balance fluctuations. A large number of mass-balance reconstructions since the beginning of the century are based on statistical relations between monthly meteorological data and mass balance. The question examined in this paper is: are these relationships reliable enough for long-term time-scale extrapolation? From the glacier de Sarennes long mass-balance observations series, we were surprised to discover large discrepancies between relations resulting from different time periods. The importance of the albedo in relation to ablation and mass balance is highlighted, and it is shown that it is impossible to ignore glacier-surface conditions in establishing the empirical relation between mass-balance fluctuations and climatic variation; to omit this parameter leads to incorrect results for mass-balance reconstruction in the past based on meteorological data.

Meteorological controls on glacier mass balance: empirical relations suggested by measurements on glacier de Sarennes, France

AbstractGlacial mass-balance reconstruction for a long-term time-scale requires knowledge of the relation between climate change and mass-balance fluctuations. A large number of mass-balance reconstructions since the beginning of the century are based on statistical relations between monthly meteorological data and mass balance. The question examined in this paper is: are these relationships reliable enough for long-term time-scale extrapolation? From the glacier de Sarennes long mass-balance observations series, we were surprised to discover large discrepancies between relations resulting from different time periods. The importance of the albedo in relation to ablation and mass balance is highlighted, and it is shown that it is impossible to ignore glacier-surface conditions in establishing the empirical relation between mass-balance fluctuations and climatic variation; to omit this parameter leads to incorrect results for mass-balance reconstruction in the past based on meteorological data.

Eastern Alpine glacier activity and climatic records since 1860

We have analyzed records of glacier-front variations, mass-balance reconstructions, temperature and precipitation data of Alpine stations, and found that the difference between summer and winter temperature in connection with winter precipitation is a useful indicator of glacier activity. Application of this parameter to the records of six stations since 1860 indicated the advance around 1920 had been preceded by a decade with frequent positive mass balances, while the period 1928–64 was characterized by increased climatic continentality and strong, uniform glacier retreats.

Eastern Alpine glacier activity and climatic records since 1860

We have analyzed records of glacier-front variations, mass-balance reconstructions, temperature and precipitation data of Alpine stations, and found that the difference between summer and winter temperature in connection with winter precipitation is a useful indicator of glacier activity. Application of this parameter to the records of six stations since 1860 indicated the advance around 1920 had been preceded by a decade with frequent positive mass balances, while the period 1928–64 was characterized by increased climatic continentality and strong, uniform glacier retreats.

Deep water nutrient and oxygen gradients in a modern coastal upwelling zone and their paleoceanographic implications

Dissolved phosphate and oxygen data from the waters at >300 m depth beneath the Peru upwelling system imitate observed onshore/offshore surface productivity data. Positive onshore phosphate gradients and negative onshore oxygen gradients are greater in deeper water (up to 1000 m), reflecting the decreasing degree of horizontal mixing at depth. Mass balance reconstructions of surface productivity, nutrient remineralization, and onshore‐offshore chemical gradients suggest that the lack of wide continental shelves during glacial climates would lead to more pronounced dissolved nutrient and oxygen gradients in the deep water adjacent to continental margins. Horizontal δ13C gradients in sediments beneath highly productive coastal upwelling zones may have been as high as 0.5–1.0‰ per 100 km, suggesting caution in the interpretation of benthic δ13C samples adjacent to continental margins during low sea level stands.

Mass-balanced paleogeographic reconstructions

Paleogeography, paleotopography, and paleobathymetry of a closed erosion-depositional system can be reconstructed by restoring sedimentary masses to elevated surfaces in a drainage basin based on the inverse of present erosion equations and adjusting for isostasy, sea level changes, sediment compaction, and thermal subsidence. The erosion-deposition history of the northwestern Gulf of Mexico margin and its western-central North American source area during the Cenozoic is used to explore the sensitivity of mass balance reconstructions, and changes in assumptions concerning erosion rate parameters and sea level. Analysis of the distributions of sedimentary material and mass-balanced paleogeographic reconstructions of the study area indicate the following specific results: