Geochemistry

The felsic lavas of the Bamenda Mountains, in the main part of the Cameroon Volcanic Line, are mainly represented by trachytes, with subordinated benmoreites and alkaline to peralkaline rhyolites. New K–Ar geochronological data define two main volcanic episodes, the first one between 18 and 22Ma, and the second one from 12.5 to 13.5Ma. Geochemical data indicate that these felsic rocks

Melt impregnated plagioclase lherzolites from the Nain mélange, central Iran, contain pyroxenes enriched and chemically zoned with Sr. Pyroxenes from the lherzolite and the clinopyroxenite seams, which have been precipitated from the impregnating melt, show similar trace element geochemical characteristics, including a similar Sr anomaly. The associated plagioclase, precipitated from the impregnating melt, has been selectively altered to isotropic saussurite. Strontium concentration increases in the pyroxenes from the core to the rim and toward crosscutting saussurite trails in orthopyroxene porphyroclast cores. The highest Sr content (up to 10.8 ppm in clinopyroxene and 3.8 ppm in orthopyroxene) is found in the finer pyroxenes surrounded by thicker saussurite layers. The Sr enrichment within pyroxenes is neither caused by metasomatism nor modified by fluids involved in hydrothermal alteration because pyroxenes are extremely depleted in fluid-mobile and light rare earth elements. Also, Sr enrichment cannot be related to the melt impregnation, since the Sr supply from the impregnating melt was consumed by plagioclase crystallization. The Sr enrichment in the pyroxene postdates the melt impregnation and is due to the relatively high-temperature (375°C-850°C) of saussuritization, that is, the breakdown of plagioclase. Plagioclase decomposition has released appreciable amounts of Sr to enrich adjacent pyroxenes. Saussurite shows significantly lower Sr contents than the plagioclase. Sr enrichment in peridotite pyroxenes, which is ascribed primarily to the metasomatism of slab-derived fluids, should be treated carefully, particularly when altered plagioclase is present.

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Multiple tracers of groundwater input (salinity, Si, 223 Ra, 224 Ra, and 226 Ra) were used together to determine the magnitude, character (meteoric versus seawater), and nutrient contribution associated with submarine groundwater discharge across the leeward shores of the Hawai'ian Islands Maui, Moloka'i, and Hawai'i. Tracer abundances were elevated in the unconfined coastal aquifer and the nearshore zone, decreasing to low levels offshore, indicative of groundwater discharge (near-fresh, brackish, or saline) at all locations. At several sites, we detected evidence of fresh and saline SGD occurring simultaneously. Conservative estimates of SGD fluxes ranged widely, from 0.02-0.65 m 3 m − 2 d − 1 at the various sites. Groundwater nutrient fluxes of 0.04-40 mmol N m − 2 d − 1 and 0.01-1.6 mmol P m − 2 d − 1 represent a major source of new nutrients to coastal ecosystems along these coasts. Nutrient additions were typically greatest at locations with a substantial meteoric component in groundwater, but the recirculation of seawater through the aquifer may provide a means of transferring terrestrially-derived nutrients to the coastal zone at several sites.

Volcano monitoring aims at the recognition of changes in instrumentally observable parameters before hazardous activity in order to alert governmental authorities. Among these parameters seismic data in general and volcanic tremor in particular play a key role. Recent major explosive eruptions such as Okmok (Aleutians) and Chaitén (Chile) in 2008 and numerous smaller events at Mt Etna (Italy), have shown that the period of premonitory seismic activity can be short (only a few hours), which entails the necessity of effective automatic data processing near on-line. Here we present a synoptic pattern classification analysis based on Self Organizing Maps and Fuzzy Cluster Analysis which is applied to volcanic tremor data recorded during a series of paroxysmal eruptive episodes and a flank eruption at Etna in 2007-2008. In total, eight episodes were analyzed; in six of these significant changes in the dynamic regime of the volcano were detected up to 9 h prior to the onset of eruptive activity, and long before changes in volcanic tremor amplitude and spectral content became evident in classical analysis. In two cases, the state transition was b 1 h before the onset of eruptive activity, which we interpret as evidence for very rapid magma ascent through an open conduit. We further detected twenty failed paroxysms, that is episodes of volcanic unrest that did not culminate in eruptive activity, between March and April 2007. As the application of the software for this synoptic pattern classification is straightforward and requires only moderate computational resources, it was possible to exploit it in an on-line application, which was tested and now is in use at the Istituto Nazionale di Geofisica e Vulcanologia in Catania for the monitoring of Etna. We believe that the pattern classification presented here may become a powerful addition to the repertoire of volcano monitoring tools and early warning techniques worldwide.

The seismicity depth distribution in the central and southern East African Rift System (EARS) is investigated using available catalogs from local, regional and global networks. We select well-determined events and make a re-assessment of these catalogs, including a relocation of 40 events and, where necessary, a declustering. About 560 events are finally used for determining foci depth distribution within 6 areas of the EARS. Assuming that short-term deformation expressed by seismicity reflects the long-term mechanical properties of the lithosphere, we build yield strength envelopes from seismicity depth distribution. Using brittle and ductile laws, we predict the strength percentage spaced every 5 km (or sometimes 2 km) in the crust, for a given composition and a specific geotherm, and constrain it with the relative abundance of seismicity. Results of this modeling indicate significant local and regional variations of the thermomechanical properties of the lithosphere which are broadly consistent with previous studies based on independent modelings. In order to explain relatively deep earthquakes, a highly resistant, mafic lower crust is generally required. We also find evidence for changes in the strength magnitude and in the depth of the brittle-ductile transitions which are clearly correlated to tectonic provinces, characterized by contrasted thermal gradients and basement types. A clear N-S increase and deepening of the peak strength level is evidenced along the eastern branch of the EARS, following a consistent southward migration of rifting sincẽ 8 Ma. We also detect the presence of a decoupling layer in the Kenya rift, which suggests persisting influences of the deep crustal structures (Archaean and Proterozoic) on the behavior of the extending crust. More generally, our results suggest that seismicity peaks and cut-off depths may provide good proxies for bracketing the brittle-ductile transitions within the continental crust.

The Timor-Tanimbar region constitutes part of the non-volcanic outer Banda Arc of Eastern Indonesia. Here, the world's youngest 'A'-type high-pressure metamorphic belt crops out with different stages of evolution. Whereas an advanced domal uplift stage is seen in Timor island, the high-pressure (HP) metamorphic belt is still in the first stage of tectonic extrusion on the eastern small islands of Kisar, Leti, Moa, Sermata and Laibobar. The metamorphic rocks on Leti are among the best exposed in the islands. They are tectonically juxtaposed against overlying ultramafic rocks and underlying unmetamorphosed continental shelf sediments, bound by normal and reverse faults, respectively. The Leti metapelites display four progressive metamorphic zones: chlorite-biotite, garnet, chloritoid-staurolite and kyanite zones, with increasing grade. Zonation in Leti metabasite unit is comparable, and progressively changes from blueschist-greenschist transition (BS/GS), through epidote-amphibolite (EA), to amphibolite (AM) facies, with increasing grade. The highest-grade metapelites and metabasites occupy structurally intermediate levels.

Within the eastern Himalayan syntaxis, carbonatite-like dykes occur in granulite facies gneisses of the Greater Himalayan Crystallines. Most dykes are dolomitic and are associated with scapolite-bearing hornblendite and glimmerite, which are separated from the country rocks by a selvage of altered rocks containing minerals such as diopside, tremolite, K-feldspar, albite, and calcite. Only a few dykes are calcitic with alteration halos containing wollastonite, calcite, anorthite, diopside, and scapolite. Dolomitic dykes as wide as several tens of metres contain irregular xenoliths of granulitic gneiss.

The Mesozoic southern branch of the Neo-Tethys Ocean was located between the Arabian shield and the Sanandaj-Sirjan continental block of Iran. The Kermanshah ophiolitic complex crops out in the Main Zagros Thrust Zone in Iran and consists of several rock associations, which record the geodynamic evolution of this ocean. In particular, the ophiolitic rocks that record the early stage of this oceanic evolution are represented by mantle metalherzolites, metagabbros and crosscutting metabasaltic dykes, as well as by basaltic pillow lavas and dykes. Mineral chemistry and whole-rock geochemistry of the metalherzolites show that they represent portions of exhumed sub-continental mantle. Four groups of rock can be recognized within the metagabbro and volcanic/subvolcanic sequences, based on many geochemical indicators and Sr-Nd isotopic data. They are: (1) metagabbros and metadykes with a N-MORB signature; (2) alkaline basalts and trachybasalts with ocean-island basalt (OIB) affinity; (3) rocks showing plume-type MORB (P-MORB) affinity; and (4) rocks showing enriched-type MORB (E-MORB) affinity. Metagabbros and metadykes show either low or high Sm/Yb ratios, which point to a genesis from partial melting of a pure depleted MORB mantle (DMM) source or a DMM source bearing garnet-pyroxenite relics, respectively. All volcanic and subvolcanic rock-types have variable, but generally high La/Yb, Sm/Yb, Th/Yb, Ta/Yb and Zr/Y ratios, and low Zr/Nb ratios. These features coupled with relatively low 143 Nd/ 144 Nd ratios and high 87 Sr/ 86 Sr indicate that the alkaline rocks were generated from an enriched, OIB-type (plume-type?) mantle source, whereas P-and E-MORB rocks can be interpreted as the product of variable interaction between depleted MORB-type asthenosphere and OIB-type material. We propose a tectono-magmatic model that can explain the different rock associations cropping out in the Kermanshah ophiolites involving a type of rifted margin that is intermediate between the amagmatic Iberia/Ligurian Tethys type and the magmatic, plume-influenced East Greenland type. This model presupposes that the Sanandaj-Sirjan block was rifted from the northern margin of Arabia through passive extension, which led to the exhumation of the sub-continental mantle now represented by the metalherzolites. Meanwhile, the asthenosphere upwelling associated with the partial melting of a heterogeneous mantle source locally bearing garnet-pyroxenite relics allowed the formation of both low and high Sm/Yb N-MORB-type metagabbros and metadykes at the continent-ocean transition zone. This model is similar to the model proposed for the Ligurian Tethys. But, in contrast with the Ligurian Tethys model, extension was also associated with volcanism characterized by a marked influence of OIB-type components linked to the uprising of MORB-type, depleted asthenospheric mantle. If so, the Kermanshah ophiolites represent a particular type of continental margin ophiolite, comprising a combination of continental margin-and plume-type ophiolites.

Hutian Kiln, located in Jingdezhen City of Jiangxi Province of China, is well-known for the productions of bluish white glazed porcelain (Qingbai) from Song Dynasties (AD 960 e AD 1279) and egg-white glazed porcelain (Luanbai) of Yuan Dynasty (AD 1271 e AD 1368). Luanbai with an opaque glaze is thought to have evolved from Qingbai, which has a transparent glaze; however, the precise technological details for this process have not been adequately studied. This paper presents the analyses of samples of Luanbai and Qingbai porcelains from Hutian Kiln using various microscopic studies, including visible light spectrometry and Energy-dispersive X-ray fluorescence. Some distinct technical changes have been identified that help to explain the evolution from transparent Qingbai to opaque Luanbai glaze. First, there is an increase in the proportion of potassium-rich ingredients in sherds dating to Late Song Dynasty, which suggests a change in the glaze recipe. Second, during Yuan Dynasty, both types of porcelain share the same chemical composition, but Luanbai products display distinct micro-structures and opacity in contrast to the Qingbai ware. Third, the overall firing temperature of Luanbai is around 1270 C which is generally around 100 C higher than that of Qingbai. The opacity of Luanbai ware may be the result of different firing techniques, including the higher firing temperature and a correspondingly longer time to heat and to cool the glazed porcelain. The results reveal new insights on the coloring mechanism of the two kinds of glaze and the transition from Qingbai of Song Dynasty to Luanbai of Yuan Dynasty.

The aim of this paper is to demonstrate that atomistic simulations can be used to evaluate the structure of mineral surfaces and to provide reliable data for forsterite surfaces up to a plane index of 2 using the code METADISE. The methods used to calculate the surface structure and energy which have more commonly been used to study ceramics are briefly explained as is a comparison with experimental data, most notable the crystal morphology. The predicted morphologies show that all the methods (Donnay-Harker, Attachment energies and equilibrium) show most of the surfaces that are expressed in observed crystals. The equilibrium morphology calculated from the relaxed surface energies is the only method which expresses the {201} surfaces and the {101} surfaces, which appear only upon relaxation. The more stable surfaces are shown to be those which have the highest surface density and more closely resemble close packed structures with highly coordinated surface ions and silicon as far from the surface as possible. The most stable surfaces the {100} which has alternating layers of MgO and SiO 2 terminating with an MgO layer. The structure is similar to the MgO {100} surfaces and has a similar energy (1.28 Jm Ϫ2 compared to 1.20). The second most stable are the {201} which have a stepped surface topology, but is also compact with a relaxed surface energy of 1.56 Jm Ϫ2. The results indicate that atomistic simulation is well suited to the prediction of surface structure and morphology although care must be taken in choosing potentials which model the structure and elastic properties accurately. Surface methodology The basic approach, used within the METADISE program (Watson et al. 1996), is to consider the crystal as a

The absence of dunite (>90 vol% olivine) in the howardite, eucrite, and diogenite (HED) meteorite suite, when viewed with respect to spectroscopic and petrologic evidence for olivine on Vesta, is problematic. Herein, we present petrologic, geochemical, and isotopic evidence confirming that Miller Range (MIL) 03443, containing 91 vol% olivine, should be classified with the HED clan rather than with mesosiderites. Similarities in olivine and pyroxene FeO ⁄ MnO ratios, mineral compositions, and unusual mineral inclusions between MIL 03443 and the diogenites support their formation on a common parent body. This hypothesis is bolstered by oxygen isotopic and bulk geochemical data. Beyond evidence for its reclassification, we present observations and interpretations that MIL 03443 is probably a crustal cumulate rock like the diogenites, rather than a sample of the Vestan mantle.

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Deposits from the Minoan Santorini (Thera) eruption in the eastern Mediterranean region constitute the most important regional stratigraphic marker in the chronological perplexity of the 2nd millennium BCE. Extensive tsunami depos- its were discovered in Crete at the Minoan archaeological site of Palaikastro, containing reworked volcanic Santorini ash. Hence, airborne deposition of volcanic ash, probably during the 1st (Plinian) eruption phase, preceded the tsunami, which was apparently generated during the 3rd or 4th phase of the eruption, based on evidence from Thera. Average radiocarbon dates (uncalibrated) of animal bones in the Palaikastro tsunami deposits along the coast (3350 ± 25 BP) and at the inland archaeo- logical site (3352 ± 23 BP) are astoundingly similar to the average 14C date for the Minoan Santorini eruption at Akrotiri on Thera (3350 ± 10 BP). The wiggle-matched 14C date of the eruption in calendar years is 1627-1600 cal BCE. Late Minoan IA pottery is the younges...

In 1962, what was then a landmark novel ‘Silent Spring’ was published, the author was Rachel Carson. The novel highlighted the effects of man made chemicals on the environment and ecosystems. Carson describes in this novel, the powerful and detrimental effects that humans have on the natural world
This report will describe the harmful effects of environmental chemicals on man and ecosystems and attempts to assess whether these effects have lessened since the publication of Rachel Carson’s ‘Silent Spring’. Scientific evidence will be presented of the changing effects of environmental chemicals through time and on a global scale. Their methods of toxicity will be described

ABSTRACT We investigated the casting cores of twelve large bronze masterpieces of the Florentine Renaissance and Mannerism (artworks by Ghiberti, Donatello, Verrocchio, Rustici, and Danti). Materials were characterized in their mineralogical-petrographic features, chemical composition, organic content and fossil traces. The results achieved provide information on the main recipes employed for manufacturing the casting cores, which largely agree with written sources of the time, and shed light on the art foundry processes between the 15th–16th centuries. The data collected point out a pronounced affinity of natural raw materials used in all the casting cores investigated, consisting in silty-sandy clays with a suitable natural fine-grained temper component. A large use of organic fibres and matters of both animal and vegetal origin and a minor use of gypsum in selected workshops (Rustici, Verrocchio) were highlighted. Textural analyses allowed gaining information on direct vs indirect methods of casting, while firing temperatures up to about 1000 °C were estimated from mineralogical and microstructural observations. Despite the strong similarities, significant differences among the various samples analysed were pointed out, providing some initial analytical clues that suggest different practices in separate workshops. Finally, the whole petrographic, geochemical and paleontological data gave information on the provenance of the clayey raw materials. This work represents the first step of a systematic approach to the classification of the core materials used in Florentine foundries along the centuries and shows the significant contribution the petrographic analyses can provide to the interpretation of the execution processes of large bronzes.

Twenty years of continuous Earth observation by satellite SAR have resulted in numerous new insights into active volcanism, including a better understanding of subsurface magma storage and transport, deposition of volcanic materials on the surface, and the structure and development of volcanic edifices. This massive archive of data has resulted in fundamental leaps in our understanding of how volcanoes work - for example, identifying magma accumulation at supposedly quiescent volcanoes, even in remote areas or in the absence of ground-based data. In addition, global compilations of volcanic activity facilitate comparison of deformation behavior between different volcanic arcs and statistical evaluation of the strong link between deformation and eruption. SAR data are also increasingly used in timely hazard evaluation thanks to decreases in data latency and growth in processing and analysis techniques. The existing archive of SAR imagery is on the cusp of being enhanced by a new gene...

Egyptlan mummies have captured the imagination of mankind for very many years. Modern analysis of mummies, using Gas Chromatography-Mass Spectrometry and High Performance Liquid Chromatography, provides information on the type of orgamc matter used in the embalming processes. A long standing controversy between modern archaeologists and ancient historians is the question of whether Dead Sea asphalt was exported to Egypt for this purpose. Analysis of biomarkers, and in particular of the steranes and pentacyclic triterpanes, allowed the unequivocal identification of Dead Sea asphalts in mummies younger than the 2nd century BC while it was absent from an older mummy. A possible interpretation for this is that export of asphalt to Egypt for embalming purposes in the last 2500 years began only after the reign of Alexander the Great when the economy of Palestme became incorporated into the Egyptian geopolitical sphere. The presence of beeswax, n-alkanes in the C,,-C,, range with odd over even preference and of aromatic compounds related to the higher plants in mummies provides an insight into the technology of embalming as utilized by the ancient Egyptians.

A 727 m thick sequence of the Lower and Mid Palaeozoic in Satun province, south peninsular Thailand is represented by a continuous succession of deeper water carbonates and clastic rocks ranging from the Caradoc to the Silurian, conformably overlain by the shallower water carbonates and clastic rocks of the

A Lower Devonian (Emsian) tentaculite fauna including Nowakia acuaria [Richer, R., 1854. Thüringische Tentaculiten. Zeitschr. Deutsch. Geol. Gesellsch. 6, 275-290] occurs in black shale in the basal part of a siliciclastic sequence exposed north of Satun, southern peninsular Thailand. Similar tentaculite beds with Nowakia have been reported from several areas in the Fang, Sri Sawat, and Trang areas of Thailand, the Langkawi Islands and the Mahang-Baling areas of Malaysia. The depositional environments in which the tentaculite-bearing black shale accumulated extended from modern northern Thailand to northwestern Malaysia during the Early Devonian (Emsian). q

Classic oxidized porphyry copper deposits (OPCD) are characterized by high tonnage and elevated f O 2 and contain highly oxidized minerals including primary anhydrite and hematite. In contrast, the Baogutu deposit contains abundant hypogene pyrrhotite and methane-rich fluid inclusions, characteristic of lower tonnage, reduced porphyry copper deposits (RPCD). Mineral paragenesis and mineral chemistry studies reveal two mineralization periods (magmatic and hydrothermal) with the hydrothermal period further subdivided into three paragenetic stages including Ca-Na alteration, potassic alteration and propylitization, locally overlapped by phyllic alteration. Several independent geothermometers indicate that the temperatures of the magma, potassic and propylitization alteration are estimated to be 600-900°C, 200-400°C and 200-300°C, respectively. Multiple indicators including mineral assemblages, apatite SO 3 content, whole rock Fe 2 O 3 /FeO ratios and fluid compositions indicate the f O 2 of the magma and hydrothermal fluid to be NNO and NNO-NNO-2, respectively. Hydrothermal fluids associated with primary biotite yield log(f H 2 O /f HCl ) fluids values of 4.8-6.2 for diorite and 4.1-4.5 for granodiorite porphyry. The logf S2 of the magmatic and potassic alteration are estimated to be 0.7 to 3.0 and 5.5 to 11.0, respectively, based on pyrrhotite and sulfide assemblages. Mineral assemblage and hessite composition suggest the logf Te2 of the potassic alteration is 8.5 to 14.5. The low tonnage Baogutu deposit displays significantly lower f O 2 than OPCDs (N NNO + 2), and, on this basis, could be classified as a RPCD. Other physicochemical conditions including T, f S2 , log(f H2O /f HCl ) fluid do not show obvious differences to those of OPCDs. We deduce that the low f O 2 of Baogutu metallogenic granitoids and aqueous fluids likely produced the unusual pyrrhotite-arsenopyrite mineral assemblage, and the NaCl-H 2 O-CH 4 -CO 2 ore-forming fluids and small tonnage typical of RPCDs. Previous obtained fluid inclusion H-O isotope data and sulfide S-Pb isotope data suggest the methane-rich oreforming fluids were derived from deep mantle source with little contamination from sedimentary components. However, detailed studies are needed to clarify the origin of the CH 4 .

Rescue excavations in Prohear, southeast Cambodia, recently saved the last untouched graves of one of the richest prehistoric sites in Southeast Asia. Many Iron Age burials dating from the 2nd century BC to the 1st century AD contained gold and silver ornaments so far unknown from archaeological contexts together with indications for the presence of an immigrated elite. A first selection of 59 objects were analysed by LA-ICP-MS to obtain detailed information about the composition, as well as minor and trace elements. The majority of the ornaments consist of electrum and auriferous silver with low copper concentrations, and two main groups indicating different alluvial gold sources can be distinguished by different concentrations of Pt, Ir, Bi and different Pd/Pt ratios, one group being related to rich burials with non-local features. The SEM and EDX analyses of four objects revealed two different gilding techniques observed for the first time in Southeast Asian artefacts: foil-fusion gilding, related to special AgeAue(Cu) eSn alloys containing up to 4% tin, and depletion gilding.

The concentration and transport of metals in hydrothermal solutions depend on how metals ions combine with ligands to form complexes, and experimental methods are necessary to identify the important complexes. UV-Vis-NIR spectrophotometry was used to study the formation of Cu(II)-chloride complexes in LiCl brines up to very high chlorinities (18 m LiCl), at temperatures between 25°C and 90°C. The number of Cu(II)-chloride complexes necessary to account for the variation in spectra with varying chloride molality at each temperature was estimated using principal component analysis. The molar absorptivity coefficients and concentrations of each complex were then determined using a "model-free" analysis, which does not require any assumption about the chemistry of the system, other than the number of absorbing species present. Subsequently, the results from the "model-free" analysis were integrated with independent experimental evidence to develop a thermodynamic speciation model, where the logarithms of the equilibrium constants for Cu(II)-chloride formation reactions were fitted to the data using a non-linear least-squares approach. Maps of the residual function were used to estimate uncertainties in the fitted equilibrium constants.

Four sets of thin-section scale, Mode I (open mode), cemented microfractures are present in sandstone from the Eocene Misoa Formation, Maracaibo basin, Venezuela. The first set of microfractures is intragranular (F1), formed early during compaction and are filled with quartz cement precipitated at temperatures equal to or higher than 100 8C. The second set of microfractures (F2) is cemented by bituminite-pyrite, formed at temperatures between 60 and 100 8C, and are associated with kerogen maturation and hydrocarbon migration from underlying overpressured source rocks. The third set of microfractures (F3) is fully cemented by either quartz cement or calcite cement. The former has fluid inclusion homogenization temperatures between 149 and 175 8C. These temperatures are mostly higher than maximum burial temperatures (~160 8C), suggesting that upward flow, caused by a pressure gradient, transported silica vertically which crystallized into the fractures. Upward decompression may have also caused a P CO 2 drop, which, at constant temperature, allowed simultaneous carbonate precipitation into the third microfracture set. The fourth set of thin-section scale microfractures (F4) is open or partially cemented by sideritehematite and other iron oxides. The presence of hematite and iron oxides in microfractures is evidence for oxidizing conditions that may be associated with the uplift of the Misoa formation. In order to time and place constraints on the depth of formation of the fourth set of microfractures, we have coupled published quartz cementation kinetic algorithms with uniaxial strain equations and determined if, in fact, they could be associated with the uplift of the formation. Our results suggest that thermoelastic contraction, caused by the formation's uplift, erosion, and consequent cooling is a feasible mechanism for the origin of the last fracture set. Hence, we infer that meteoric water invasion into the fractures, at the end of the uplift, cause the precipitation of oxides and the transformation of siderite to hematite. D

A study has been done in Luvuvhu Catchment to develop a framework for effective community participation in water quality monitoring and management. Community participation and involvement in development has since the 1970s gathered momentum among the non-governmental organisations (NGOs) fraternity but has never gained clear status with Governments world over. In South Africa the policy and legal frameworks for community consultation, involvement and participation are clearly spelt out on paper starting with the country's constitution. The division of the country into Water Management Areas (WMA) and the formation of Catchment Management Agencies (CMA), Water User Associations (WUAs) for example, was meant to increase participation of stakeholders including communities in the management of water resources. These efforts have not translated into effective participation by local communities in the management of water resources because there is no link between the national water quality management frameworks and community based development structures.

1] Lower crustal earthquakes are commonly observed in continental rifts at depths where temperatures should be too high for brittle failure to occur. Here we present accurately located earthquakes in central Ethiopia, covering an incipient oceanic plate boundary in the Main Ethiopian Rift. Seismicity is evaluated using the combination of exceptionally well resolved seismic structure of the crust and upper mantle, electromagnetic properties of the crust, rock geochemistry, and geological data. The combined data sets provide evidence that lower crustal earthquakes are focused in mafic lower crust containing pockets of the largest fraction of partial melt. The pattern of seismicity and distribution of crustal melt also correlates closely with presence of partial melt in the upper mantle, suggesting lower crustal earthquakes are induced by ongoing crustal modification through magma emplacement that is driven by partial melting of the mantle. Our results show that magmatic processes control not only the distribution of shallow seismicity and volcanic activity along the axis of the rift valley but also anomalous earthquakes in the lower crust away from these zones of localized strain.

NORMAT is a new technique for quantifying hydrothermal alteration in greenschist facies rocks using normative mineral ratios without precursor or mineralogical determination. Using five petrologic rules, the NORMAT calculations first compute normative alteration (paragonite, sericite, chlorite, pyrophyllite) and precursor minerals (albite, orthoclase, anorthite), as well as normative loss on ignition (LOI) and CO 2 contents. The results are then computed as alteration indices that quantify the overall alkali element depletion in terms of the paragonitization, sericitization, chloritization and pyrophillitization components. Equations for the alteration indices are ratios between the normative alteration and precursor minerals, thus providing a relative numerical measure of alteration intensity that is independent of protolith. Alteration by carbonatization is quantified by the IPAF index, which represents the position of the sample's analytical LOI value within a range bounded by CO 2-free normative LOI and maximum possible normative LOI-CO 2 content. This procedure also allows the CO 2 content to be estimated from LOI, which can then be used to calculate normative carbonate minerals. Alteration index (AI) values and normative minerals for 28 selected samples from the Val d'Or Formation illustrate the main properties of normative mineral ratio alteration indices.

The use of mineral deposit density regression models to estimate the number of undiscovered deposits is gaining acceptance in mineral resources assessments. The deposit density regression models currently in use are based on well-established power law relationships between deposit density (deposits/km 2 ) and the areal extent of the host rocks in well explored regions (control areas) worldwide. Although these generalized or global deposit density models can generate guideline estimates that are useful at the terrane scale, locallyderived terrane-based deposit density regression models may potentially yield more relevant estimates at the terrane scale. Using 12 selected komatiite-defined control areas in the Kalgoorlie Terrane, Western Australia, we found that the size (km 2 ) of the control areas had power law relationships with (i) nickel sulphide deposit density, and (ii) nickel endowment density (nickel metal/km 2 ). Regression analyses showed that both power law relationships are statistically significant at the 5% level. This suggests that nickel sulphide deposit and endowment density models could be used to estimate the number of undiscovered nickel sulphide deposits and amount of nickel metal endowment in less explored komatiites in the Kalgoorlie Terrane. This study shows that global geological relationships can be viably downscaled onto local geological terranes thereby supporting the hypothesis that the processes of mineral deposit formation and preservation are scale-independent and self-similar.

A revised kinematic model is proposed for the Neogene tectono-magmatic development of the North Tanzanian Divergence where the axial valley in S Kenya splits southwards into a wide diverging pattern of block faulting in association with the disappearance of volcanism. Propagation of rifting along the S Kenya proto-rift during the last 8 Ma is first assumed to have operated by linkage of discrete magmatic cells as far S as the Ngorongoro-Kilimanjaro transverse volcanic belt that follows the margin of cratonic blocks in N Tanzania. Strain is believed to have nucleated throughout the thermally-weakened lithosphere in the transverse volcanic belt that might have later linked the S Kenya and N Tanzania rift segments with marked structural changes along-strike. The North Tanzanian Divergence is now regarded as a two-armed rift pattern involving:

Four blue-glazed faience jars, on exhibition in the Louvre Museum, are referred to as the canopic jars of Rameses II. Their recent typological re-examination rendered this original assignment questionable. In order to clearly determine their use, a study of two successive organic residues from the canopic jars, using molecular biomarkers analysed by GC-MS and LC-MS and absolute dating by 14 C, was initiated. The results revealed that these two materials were not contemporary to the reign of Rameses II. The first one, scraped from the interior face of one jar, was identified as an unguent made of coniferous oil and animal fat and dated from the Third Intermediate Period. The second one, originally stored with glued linen inside one jar, is likely an embalming substance, made of pure vegetable resin (Pistacia) and dated from the Ptolemaic Period. These results clarify a controversy which has been lasting over a century. The famous blue-glazed faience jars are not the canopic jars of Rameses II but are confirmed as situlae which were reused at least two times: first to store unguents during the Intermediate Period and later to store embalming packages of an unknown person during the Ptolemaic period.

Mineral exploration in areas of little bedrock exposure must increasingly rely on the predictive quality of geological, geochemical and geophysical data. In this contribution analysis of fluid inclusions is used to characterize fluid systems associated with alteration and mineralization in two locations in South Australia. In the Curnamona Province, fluids related to albitization and calc-silicate alteration with associated brecciation evolve from a saline sodic composition to a metalliferous, saline fluid also found associated with sulphide mineralization. The microthermometric distinction of inclusion types is evidence for pressure fluctuation as a cause for breccia formation. In the Central Gawler Craton gold province fluid inclusion studies have characterized the compositional and constrained the physical conditions of mineralizing fluids. Regionally identified low salinity CO 2 -bearing fluids at temperatures b 350°C and pressures b 1.5kbar indicate a shallow-level orogenic [Groves, D.I., Goldfarb, R.J., Gebre-Mariam, M., Hagemann, S.G., Robert, F., 1998. Orogenic gold Deposits: A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Ore Geology Reviews, 13, 7-27.] or intrusion-related [Lang, J.R., Baker, T., 2001. Intrusion related gold systems: the present level of understanding. Mineralium Deposita, 36, 477-489.] setting for the mineralization.