A crustal section across the Eastern Alps based on gravity and seismic refraction data

Summary Existing gravity and seismic refraction data are used to deduce a crustal cross section across the Eastern Alps along the meridian 11°.4 East. The results suggest that a high density body of the Ivrea type is present under the southern margin of the Alps, that the Apennines do not have a crustal root extending to a depth of 50 km and that a profound discontinuity extending to the base of the crust exists between the Apennines and the Po Valley.Lamont-Doherty Contribution No. 1590.     

The effect of earth orientation errors in baseline determination

The determination of baseline lengths from certain space techniques is based on the derived coordinates of the terminal stations. As such, the estimated baselines are susceptible to systematic errors that affect the relative coordinates. One source of error is in the set of parameters which describes the continuously changing relative orientation of the Conventional Terrestrial (CTS) and Inertial (CIS) Reference frames. Due to these errors, the coordinates of each terminal station may in fact refer to a slightly different coordinate svstem, and, therefore, when used for computing the length between the stations, errors will result. The expected magnitudes of such errors and their possible presence in current solutions are investigated. In conclusion, we find that the present level of accuracy and stability of the available parameters connecting the CTS and CIS (e.g., the ERP series) is unsatisfactory for centimeter level baseline length determinations. The available options are either the use of strictly simultaneous SLR data sets (similar to the VLBI data sets) or the improvement of the parameters connecting the CTS and the CIS. The first long-range step in the latter direction is the support of the IAG/IAU Joint Working Group COTES proposal [CSTG Bulletin, 1982], endorsed by both the IAG and IAU in various resolutions [IAU, 1983; IAG, 1982]. Presented at the Annual Fall Meeting of the American Geophysical Union, San Francisco, December 7–15, 1982, and at the Fifth Annual NASA Geodynamics Program Conference and Crustal Dynamics Project Review, Washington, D.C., January 24–28, 1983.     

An unusual fluvial to tidal transition in the mesoarchean Moodies Group, South Africa: A response to high tidal range and active tectonics

The Moodies Group in the Dycedale Syncline, Barberton Greenstone Belt consists of a 100–130 m-thick upward-fining succession that exhibits a transition from fluvial to tide-modified sedimentation. A basal, 10–30 m-thick conglomerate–sandstone interval of alluvial origin is overlain by stacked upward-fining, decimeter- to meter-scale cycles within which three facies are recognized: 1) conglomerate lag; 2) cross-bedded sandstone; and 3) interlaminated sandstone–siltstone and mudstone. Within the cycles, the abundance of mudstone drapes increases upwards. Structureless conglomerates and cross-beds lacking mudstone drapes record braided-alluvial processes. In contrast, cross-beds with mudstone drapes and interlaminated sandstone–siltstone and mudstone are products of flows modified by various tidal beats. Sand and/or silt transport took place during the ebb and flood stages and mudstone accumulated during slack water phases. Alternating thick–thin laminations reflect dominant and subordinate, twice-daily tides. Thicker groupings of foresets and thicker intervals of vertically stacked sandstone–siltstone and mudstone laminations are interpreted as spring tide deposits whereas thinner groupings of foresets and thinner laminations record neap tides. Desiccated mudstone drapes on foresets indicate that bedforms rarely were locally exposed during some portion of the tidal cycle. Abundant exposure structures in the interlaminated sandstone–siltstone and mudstone facies indicate that the cycles are upward shoaling. The stacked upward-fining cycles are attributed to alternating subaerial exposure and fluvial influx followed by marine inundation, probably related to absolute sea level fluctuations. Lack of high-order vegetation on the Archean landscape promoted rapid lateral migration or avulsion of tidally influenced fluvial channels.

The association of facies within the 100–130 m-thick upward-fining succession is comparable to Holocene and ancient paleovalley fills characterized by basal alluvial gradational upwards into estuarine facies. However, in the absence of vegetation, the land–ocean interface in the Archean probably consisted of laterally extensive fan or braid deltas rather than point sources of sediment characteristic of most modern rivers. The abrupt up-section change from syntectonic, high-energy, alluvial–fluvial flash flood deposits to tide-influenced sedimentation implies a proximal source that provided sediment to a shoreline influenced by strong tidal action. Possible Holocene analogues are orogenic settings such as the Canterbury Plains of New Zealand, the Indo-Gangetic Plains of India and strike-slip settings such as the Gulf of Aqaba but all three examples lack a direct transition to tidally influenced sedimentation.     

REMARKS ON THE TENTH ANNIVERSARY OF ACTA METEOROLOGICA SINICA

It is hard to believe that Acta Meteorologica Sinica is celebrating its tenth brithday.Itseems like just a few months ago that AMS was formed and I was asked to serve as a foreignmember of the AMS Editorial Committee.But,indeed it has been ten years and it has been a     

Untersuchungen zum Stickstoff-, Phosphor- und Kaliumeintrag in das Grundwasser nach Gülledüngung

About 53 million tons of liquid manure from the animal husbandry plants of the GDR are used for purposes of organic fertilization per year. Fertilization by liquid manure must be reasonably done, since there should be avoided fertilization and yield losses of agriculture and damages to the ground-water as a drinking-water resource. In dependence on the cultivation of crops, the kinds of graining of soils, the month of application and of the quantity used–referred to the application of nitrogen of liquid manure in kg/ha–the enrichment effect of nitrogen, potassium and phosphorus in infiltration water is determined with the aid of lysimeter investigations. Components of nitrogen which are not used by plants get into ground-water as undesired nitrate, partly through nitrification processes. Unused potassium, too, migrates into ground-water, whereas phosphorus is bound by soil. By proposals for new limit values of load with liquid manure, summarized in tabular form, the valid specifications of the GDR standards “TGL” are criticized.     

Bacterial Production Stimulated Across the Zone of Influence of a Ground Water Circulation Well in a BTEX-Contaminated Aquifer

Benzene, toluene, ethylbenzene, and xylene (BTEX) hydrocarbons are typically the most abundant carbon source for bacteria in gasoline-contaminated ground water. In situ bioremediation strategies often involve stimulating bacterial heterotrophic production in an attempt to increase carbon demand of the assemblage. This may, in turn, stimulate biodegradation of contaminant hydrocarbons. In this study, ground water circulation wells (GCWs) were used as an in situ treatment for a fuel-contaminated aquifer to stimulate bacterial production, purportedly by increasing oxygen transfer to the subsurface, circulating limiting nutrients, enhancing bioavailability of hydrocarbons, or by removing metabolically inhibitory volatile organics. Bacterial production, as measured by rates of bacterial protein synthesis, was stimulated across the zone of influence (ZOI) of a series of GCWs. Productivity increased from ∼10² to >10⁵ ng C/L hour across the ZOI, suggesting that treatment stimulated overall biodegradation of carbon sources present in the ground water. However, even if BTEX carbon met all bacterial carbon demand, biodegradation would account for <4.3% of the total estimated BTEX removed from the ground water. Although bacterial productivity measurements alone cannot prove the effectiveness of in situ bioremediation, they can estimate the maximum amount of contaminant that may be biodegraded by a treatment system.     

Stream response to repeated coseismic folding, Tiptonville dome, New Madrid seismic zone

Fluvial response to tectonic deformation is dependent on the amount and style of surface deformation and the relative size of the stream. Active folding in the New Madrid seismic zone (NMSZ) forms the Tiptonville dome, a 15-km long and 5-km wide surface fold with up to 11 m of late Holocene structural relief. The fold is crossed by streams of varying size, from the Mississippi River to small flood-plain streams. Fluvial response of these streams to repeated coseismic folding has only been preserved for the past 2.3 ka, since the Tiptonville meander of the Mississippi River migrated across the area forming the present flood plain. This surface comprises a sandy point-bar deposit locally overlain by clayey overbank and silty sand crevasse-splay deposits, an abandoned chute channel infilled with laminated sandy silt and silty clay, and an abandoned neck cutoff filled with a sandy cutoff bar and silty clay oxbow lake deposits.Dating various stream responses to coseismic folding has more tightly constrained the timing of earthquake events in the central NMSZ and provides a means of partitioning the deformation amount into individual seismic events. Three earthquakes have been dated in the Reelfoot Lake area, ca. A.D. 900, 1470, and 1812. The latter two earthquakes had large local coseismic deformation. Both of these events were responsible for numerous stream responses such as shifting depocenters, modification of Mississippi River channel geometry, and derangement of small streams. Overbank sedimentation ceased on the dome as it was uplifted above the normal flood stage, and sedimentation of crevasse-splay deposits from the Mississippi River, colluvium from the scarp, and lacustrine sediment accumulated in the adjacent Reelfoot basin. The much larger Mississippi River channel responded to uplift by increasing its sinuosity across the uplift relative to both upstream and downstream, increasing its width/depth ratio across and downstream of the uplift, and decreasing the width/depth ratio upstream of the uplift. Despite the size of the Mississippi River, it has not yet attained equilibrium since the latest uplift 190 years ago. Small channels that could not downcut through the uplift were filled, locally reversed flow direction, or formed a lake where they were dammed.Uplift and stream response to folding along the Tiptonville dome is less dramatic between 2.3 and 0.53 ka. During this interval, abandoned channel fill and overbank deposition across the dome suggests that it was not a high-relief feature. One earthquake event occurred during this interval (ca. A.D. 900), but coseismic stream response was probably limited to a slight aggradation of a small flood-plain stream.