The concentrations of the heavy metals in the four new Antarctic meteorites Yamato (a), (b), (c) and (d) and in Orgueil, Murray, Allende, Abee, Allegan, Mocs and Johnstown

All active midocean ridges show a uniform relationship between depth and age of the oceanic crust. Recently, it has been shown by numerical methods that convective flow in a Newtonian fluid will have a positive gravity anomaly and an upward surface deformation associated with an ascending limb. If there is thermal convection in the upper mantle, these calculations predict that there may be a correlation between free air gravity anomalies and differences from the uniform relationship between oceanic depth and age. To investigate such a correlation, we considered the crestal elevation and free air gravity anomaly over the crest of the midocean ridges. It has been suggested that the differences from the depth versus age relationship are related to spreading rate. Thus, we also considered a correlation between crestal elevation and changes in rate along the ridge axis.We found a positive correlation between free air gravity and differences in crestal depth of the midocean ridge system. We found no correlation between spreading rate and gravity and no uniform relationship which holds in all the oceans between spreading rate and observed crestal depths.The long wavelength gravity anomalies which are correlated with the differences in crestal depth cannot be supported by an 80 km thick lithosphere. Thus, they are considered evidence of flow within the aesthenosphere. Further, the correlation between gravity anomaly and differences in crestal depth has the same sign and gradient as predicted by the investigations of convection in a Newtonian fluid.     

Maar-diatreme phreatomagmatism at Hopi Buttes,Navajo Nation (Arizona), USA

Remnants of an extensive maar-diatreme volcanic field are magnificently exposed at various depths of erosion in the Hopi Buttes volcanic field of northeastern Arizona. Field and petrographic studies of both the maar and diatreme elements of a selection of volcanoes within the field show that: (1) lower sections of the maar rim sequences are typically rich in sandy mudrock derived from the pre-eruptive Mio-Pliocene Bidahochi Formation, and the muddy Bidahochi sediment was soft and wet at the time of maar eruptions; (2) beds higher within the rims contain generally increased proportions of sandstone clasts from the Triassic Wingate Formation. In the diatremes, late-emplaced breccia has deeper-seated lithics than more marginal breccia emplaced earlier; and (3) many vents are topped by megacryst-enriched scoria and spatter, and deep-seated xenoliths are known only from upper diatreme and craterfilling tephra. These observations show that: (1) eruptions at Hopi Buttes involved interaction of magma with unconsolidated mudrock at shallow levels, and the phreatomagmatic processes that provided the bulk of the energy involved in the violent eruptions were driven by the interaction of magma and wet sediment; (2) the locus of explosive activity migrated downward as eruptions progressed; and (3) the closing stage of many eruptions was characterized by rapid magma rise and relative depletion of water.     

Impaired Functions in Nile Tilapia,Oreochromis niloticus (Linnaeus, 1757), from Polluted Waters

Oreochromis niloticus is an endemic species in the River Nile and represents the main object of fishery in the Nile Delta Lakes of which Lake Maryût is the smallest and most polluted. Due to current pollution problems, fish production in the lake greatly declined. Besides fish biology, this study considered a wide array of water databases in selected sites along the lake. Hydrologic and biologic data were compared to that of a reference fish hatchery. Water concentrations of ammonia, manganese, nickel, cadmium, lead and mercury proved hazardous to fish, whereas chromium, copper, iron, zinc, pH, alkalinity, hardness, phosphate, nitrate, and nitrite always fell within acceptable levels. Physiologic evaluation of O. niloticus pointed out improper growth, protein inadequacy, and functional impairment in fish inhabiting polluted sites, in particular the lake main basin. These were reflected by data of specific formulae as RNA/DNA and the relative RNA content (r) in cells of the liver and gill arches as well as by the relative mobilization of serum protein fractions. It seems, however, that growth competence is additionally affected by the stress impact exerted upon fish by massive population numbers in some cramped commercial ponds.     

Seismic Hazard of the Circum-Pannonian Region,Reprint from Pure and Applied Geophysics (PAGEOPH), Vol.l57(2000), No.1/2, 284 pages

Studia Geophysica et Geodaetica -     

Adsorption of Chromium(III), Nickel(II), and Copper(II) from Aqueous Solution by Activated Alumina

The possible use of activated alumina powder (AAP) as adsorbent for Cr(III), Ni(II), and Cu(II) from synthetic solutions was investigated. The effect of various parameters on batch adsorption process such as pH, contact time, adsorbent dosage, particle size, temperature, and initial metal ions concentration were studied to optimize the conditions for maximum metal ion removal. Both higher (molar) and lower (ppm) initial metal ion concentration sets were subjected to adsorption on AAP. Adsorption process revealed that equilibrium was established in 50 min for Cr(III) at pH 4.70, 80 min for Ni(II) at pH 7.00, and 40 min for Cu(II) at pH 3.02. Percentage removal was found to be highest at 55°C for Cr(III) and Ni(II) with 420 µm and 45°C for Cu(II) with 250‐µm particle size AAP. A dosage of 2 g for Cr(III), 8 g for Ni(II), and 10 g Cu(II) gave promising data in the metal ion removal. The adsorption process followed Langmuir as well as Freundlich models. The thermodynamics of adsorption of these metal ions on activated aluminum indicated that the adsorption was spontaneous and endothermic in nature. Present study indicates that AAP can act as a promising adsorbent for industrial wastewater treatment.     

Plastic ingestion in Franciscana dolphins, Pontoporia blainvillei (Gervais and d'Orbigny, 1844), from Argentina

Plastic debris (PD) ingestion was examined in 106 Franciscana dolphins (Pontoporia blainvillei) incidentally captured in artisanal fisheries of the northern coast of Argentina. Twenty-eight percent of the dolphins presented PD in their stomach, but no ulcerations or obstructions were recorded in the digestive tracts. PD ingestion was more frequent in estuarine (34.6%) than in marine (19.2%) environments, but the type of debris was similar. Packaging debris (cellophane, bags, and bands) was found in 64.3% of the dolphins, with a lesser proportion (35.7%) ingesting fishery gear fragments (monofilament lines, ropes, and nets) or of unknown sources (25.0%). PD ingestion correlated with ontogenetic changes in feeding regimes, reaching maximum values in recently weaned dolphins. Because a simultaneous increase in gillnet entanglement and the bioaccumulation of heavy metals take place at this stage, the first months after trophic independence should be considered as a key phase for the conservation of Franciscana dolphin stocks in northern Argentina.     

Ultramafic intrusion triggers hydrothermal explosions at Colle Fabbri (Spoleto, Umbria), Italy

The eroded Colle Fabbri volcano comprises intrusive and extrusive rocks which cover an area of about 10,000 m² in the Umbria region, Central Italy. The outcrop is located at the SW boundary of the Umbria Valley Graben (Umbria Region) on an N140 normal fault inside the Intramountain Ultra-Alkaline Province of carbonatite and melilitite rocks of central–southern Italy. A field survey of the outcrop allowed a reconstruction of igneous activity events of this unusual small-scale volcano. It is younger than 0.7 m.y. and rests on Lower Pleistocene conglomerates with intercalated clay beds. A palaeosoil marks the base of the volcanic sequence. It follows several metres of extrusive breccias composed of fragments of thermometamorphosed clay and travertine. Key features of these breccias are mud shells on blocks, plastic mud lumps, slumps, and mechanical injection from one layer into another, as well as plastic and vesiculated, micro-brecciated matrix. The breccias are cemented by a variety of silicate, sulphate, and sulphate–carbonate minerals deposited by intense hydrothermal circulation. The breccias are related to phreatic explosions triggered by the eruption of a superficial hydrothermal system. Up to 1 m thick sill and a dykelet swarm intrude the breccias. In the southern part of the outcrop there is a plug of melilitolitic composition which intrudes the breccias and deforms them upward. A variety of contact breccias is also scattered around the sill and the plug. In some places, hyaloclastite formed when melt invaded water pockets contained in the encasing rocks under hydrostatic pressure conditions. A thermal aureole, which moves up to 10 m away from the contact, is characterised by cordierite–trydimite association, thus indicating high-temperature (>>1000 °C) contact phenomena.     

Studies on Limnobiotic Conditions in a Thermal Spring at Tajura, (Tripoli), Libya

Summary: Studies on a hot spring at Tajura (Libya) indicated narrow fluctuations in water temperature (43 … 44.5 °C) near the source site. A wide thermal gradient of 10 K between two sampling sites (near the source and in the marsh) recorded in December narrowed to 3 … 4.5 K in March. Similar pH values (6.7) near the source increased along the runoff channel and touched 6.9 in the marsh. Bicarbonate alkalinity always exceeded 400 mg/l; likewise conductivity was remarkably high (>4700 μS/cm). Scarce algal growth was observed near the source site, though mats of variable thickness prevailed along the runoff channel and in the marsh.     

Magnetostratigraphy across the Berriasian-Valanginian stage boundary (Early Cretaceous), at Cehegin (Murcia Province, southern Spain)

The Berriasian-Valanginian stage boundary near the town of Cehegin in the eastern Subbetic Cordillera of Spain is documented by a detailed ammonite zonation in pelagic limestones. Two magnetostratigraphic sections spanning the uppermost ammonite subzone of the Berriasian and the lower two zones of the Valanginian yielded identical magnetic polarity patterns. Remanent magnetization is predominantly carried by magnetite, and characteristic directions were obtained by thermal demagnetization. The mean characteristic directions from both sites have an inclination of 48°; however, the site declinations are divergent (030° and 074°) due to the tectonic disturbance of the region. The Cehegin polarity pattern can be correlated by means of ammonite and calpionellid zonation to the magnetostratigraphies of the Berriasian stratotype and several Italian sections, thereby enabling a unique correlation to the M-sequence magnetic polarity time scale. The Berriasian-Valanginian stage boundary is in the middle of normal-polarity chron M15n.     

Volcanic hazards at Mount Semeru,East Java (Indonesia), with emphasis on lahars

Mt. Semeru, the highest mountain in Java (3,676 m), is one of the few persistently active composite volcanoes on Earth, with a plain supporting about 1 million people. We present the geology of the edifice, review its historical eruptive activity, and assess hazards posed by the current activity, highlighting the lahar threat. The composite andesite cone of Semeru results from the growth of two edifices: the Mahameru ‘old’ Semeru and the Seloko ‘young’ Semeru. On the SE flank of the summit cone, a N130-trending scar, branched on the active Jonggring-Seloko vent, is the current pathway for rockslides and pyroclastic flows produced by dome growth. The eruptive activity, recorded since 1818, shows three styles: (1) The persistent vulcanian and phreatomagmatic regime consists of short-lived eruption columns several times a day; (2) increase in activity every 5 to 7 years produces several kilometer-high eruption columns, ballistic bombs and thick tephra fall around the vent, and ash fall 40 km downwind. Dome extrusion in the vent and subsequent collapses produce block-and-ash flows that travel toward the SE as far as 11 km from the summit; and (3) flank lava flows erupted on the lower SE and E flanks in 1895 and in 1941–1942. Pyroclastic flows recur every 5 years on average while large-scale lahars exceeding 5 million m³ each have occurred at least five times since 1884. Lumajang, a city home to 85,000 people located 35 km E of the summit, was devastated by lahars in 1909. In 2000, the catchment of the Curah Lengkong River on the ESE flank shows an annual sediment yield of 2.7 × 10⁵ m³ km⁻² and a denudation rate of 4 10⁵ t km⁻² yr⁻¹, comparable with values reported at other active composite cones in wet environment. Unlike catchments affected by high magnitude eruptions, sediment yield at Mt. Semeru, however, does not decline drastically within the first post-eruption years. This is due to the daily supply of pyroclastic debris shed over the summit cone, which is remobilised by runoff during the rainy season. Three hazard-prone areas are delineated at Mt. Semeru: (1) a triangle-shaped area open toward the SE has been frequently swept by dome-collapse avalanches and pyroclastic flows; (2) the S and SE valleys convey tens of rain-triggered lahars each year within a distance of 20 km toward the ring plain; (3) valleys 25 km S, SE, and the ring plain 35 km E toward Lumajang can be affected by debris avalanches and debris flows if the steep-sided summit cone fails.     

1981年的广东海丰地震群

1981年,1—5月,海丰梅陇地区连续发生一些小地震,截至5月底止,总计达1764次,其中M_L≥1.0的为477次,M_L≥2.0的为15次,最大震级为M_s=3.9。 据三分向梅陇地震台及三个单分向流动地震台测定,震中分布在海丰梅陇东南3.5—6公里的联安公社坡平一带。震中密集区长轴平行于海丰-梅陇断裂,沿北东向展布,长约5公里,短轴呈北西向,宽约3公里(图1)。震源深度为3—7.5公里,而90％的震源集中在深4.5—6.5公里处(图2)。震源体小,深度浅,不易积累大的应变能,这是小震群的一个明显特征。东京大学地震研究所过浦贤认为震群是发生在地应力     

1988年11月22日甘肃肃南5.7级地震

1.地震的基本参数及序列根据甘肃区域地震台网和全国地震台网测定,这次地震的基本参数是: 发震时刻:1988年11月22日01时46分1.7秒; 震中位置:北纬38°35′,东经99°32′,即肃南县城以南的祁连山中;     

Long-period of the 1999 ground motion characteristic Jiji （Chi-Chi）, Taiwan, mainshock and aftershocks

This paper investigates long-period ground motion characteristic of the 1999 Jiji （Chi-Chi）, Taiwan, mainshock and aftershocks on the basis of lots of high quality digital strong motion records. The study attaches the importance to the variation of strength of the long-period ground motion with the magnitude, distance, and site condition. In the meantime, the near-fault long-period ground motion characteristic is analyzed. The result shows that the shape of the long-period response spectrum is mainly controlled by site condition and magnitude （the spectrum of class D＋E is wider than that of class B＋C, and the spectrum of larger magnitude is wider than that of smaller magni- tude）, and the effect of fault distance on the shape is not evident. And near-fault long-period ground motion characteristic depends on fault activity apparently, that is to say, the long-term ground motion in the hanger is stronger than that in the footwall, and the long-term ground motion in the north is stronger than that in the south.     

Field measurements of volcanic gases. Vulcano Island (Italy), Kilauea (Hawaii,U.S.A.), Merapi (Java,Indonesia)

A field gas chromatograph, built in 1978, was used in the field to directly analyse volcanic gases before water vapor condensation. Tested in Vulcano (Italy), Kilauea (Hawaii) and Merapi (Indonesia), this field measurement technique provides the actual composition of the volcanic gas mixture. The technique avoids the depletion of sulfur gases and the dissolution of the acid gases in the condensed water during the cooling. Thus the mixture of H₂S and SO₂ in fumarolic and high temperature gases (up to 819°C) in equilibrium at the emission temperature was examined.