Macrobioerosion and Microbioerosion in Marine Molluscan Shells from Holocene and Modern Beaches (39°−40°S, South of Buenos Aires Province, Argentina)

The marine sediments of the area of Verde Peninsula-Jabali Island(39°28′S/62°19′W-40°28′S/62°11′W) Holocene in age(3-2 ky),and modern beaches contain a significant amount of bioeroded mollusc shells.Fifteen sites were analyzed,in which 20.11%of the mollusc shells(2168 valves) presented bioerosion traces,in 54 species(30 bivalves and 24 gastropods).Fourteen ichnogenera were reported:Entobia,Maeandropoiydora,Iramena,Caulostrepsis,Pennatichnus,Pinaceocladichnus,Trypanites,and Gastrochaenolites(Domichnia),Gnathichnus and Radulichnus(Pascichnia),Finichnus and Centrichnus(Fixichnia),Oichnus(Praedicnia)(macrobioerosion),y Semidendrina(microbioerosion),the latter is first reported in mollusc shells in Argentina.Eleven ichnospecies were identified Finichnus peristroma,Maeandropoiydora sulcans,Gnathichnus pentax,Pinaceocladichnus onubensis,Caulostrepsis taeniola,Centrichnus eccentricus,Radulichnus inopinatus,Oichnus simplex,Oichnus paraboloides,Oichnus gradatus,and Gastrochaenolites torpedo(lithic remains).The dominant ichnogenera in the Holocene deposits are Iramena,Entobia and Oichnus.The same ichnogenera are constant with different abundance in the modern beaches,and increasing representation of Pinaceocladichnus and Pennatichnus.The dominant ichnofacies in the Holocene deposits is Trypanites,revealing a benthonic marine community composed of cheilostome bryzoans,clionaid sponges,predator gastropods,regular echinoids,polychaete annelids,bivalves,thallophytas and fungi.Generally,the area was described as a sublittoral,low-energy,stable environment with high rate of oxygenation,and sandy bottoms,with rocky bottoms at Villalonga locality.     

Cultural heritage and geological hazards: the case of the Calomini hermitage in Tuscany (Italy)

The Calomini hermitage is located on a steep slope, below an 80- to 130-m-high hanging rock wall. The hermitage, a significant example of religious architecture, has been a pilgrimage place since the Middle Ages. The monastery, completed by the tenth century, is built into the rock mass for more than half of its length. The stability and safety of the complex are threatened by stability problems in the rock slope. Structural and geotechnical investigations were carried out, showing the potential for rock blocks slides, particularly under dynamic conditions, with the fall of middle size blocks. Recently, some remedial works have been carried out, and wire meshes have been hung on the rock wall. Nevertheless, a significant portion of the Calomini hermitage area may be still dangerous and exposed to severe landslide hazard. Therefore, further research and countermeasures are necessary to protect a very important item of Italian cultural and architectural heritage.     

A new project to monitor land subsidence in the northern Venice coastland (Italy)

The paper deals with the implementation of a levelling and Global Positioning System (GPS) network to control land subsidence in the coastal area north of the Venice Lagoon. About 480 km of levelling lines with 527 benchmarks, 45 of which suited for Differential GPS measurements, were established in 2004. A complete survey of the net was carried out in 2004 soon after its establishment. The 2004 records have been compared with previous scattered data obtained by the use of levelling surveys, DGPS and SAR interferometry. The results show a trend in land settlement that increases from the lagoon margin to the north and jeopardize the Venice coastland. Groundwater withdrawals for domestic, agricultural, and health spas uses, peat oxidation of reclaimed marshlands for farming, natural consolidation of the Holocene deposits, and tectonics of the pre-Quaternary basement are the causes of land subsidence in the study area. Since most of the area lies below the mean sea level and on account of the expected sea level rise due to global change, a detailed monitoring of land displacements in the near future will be of paramount importance to plan necessary works for coastland protection.     

Provenance of the Lower Paleozoic Balcarce Formation (Tandilia System, Buenos Aires Province, Argentina): Implications for paleogeographic reconstructions of SW Gondwana

Lower Paleozoic moderately sorted quartz–arenites from the Balcarce Formation deposited in eastern Argentina (Tandilia System) comprise mainly detrital material derived from old upper crustal material. The sources were magmatic, sedimentary, and subordinated felsic metamorphic terranes. High concentrations of tourmaline and Ti-rich heavy minerals, including zircon and nearly euhedral chromite, are common. Trace element concentrations (Nb, Cr) on rutile indicate pelitic and metabasaltic sources, respectively. Major element analyses on chromites indicate a basic volcanic protolith of mid-oceanic ridge origin, which was exposed close to the depositional basin. The delivery of chromite may be associated with convergent tectonics causing the consumption and obduction of oceanic crust during pre-Upper Ordovician times. The oblique/orthogonal collision of the Precordillera Terrane with the western border of the Rio de la Plata Craton, west of the Balcarce Basin or source further to the east from a Lower Palaeozoic extensional basin are possibilities.Geochemical and petrographic data exclude the underlying Precambrian and Cambrian sedimentary rocks as dominant sources, and favour the basement of the Río de La Plata Craton, including Cambrian rift-related granites of South Africa and the Sierras Australes (eastern Argentina), as main suppliers of detritus. Trace element geochemistry of recycled pyroclastic material, associated with the quartz–arenites, also suggests volcanic arc sources. The provenance of the pyroclastic material may either be the Puna–Famatina arc, located in north and central Argentina, or a hypothetical active margin further to the south. These ash layers are equivalent in age to volcanic zircons found in the Devonian Bokkeveld Group in western South Africa.The deposition of a glacial diamictite of Hirnantian age (Sierra del Volcán Diamictite) is interpreted as a member of the Balcarce Formation. Based on the stratigraphic re-location of the glacial diamictite and trace fossils, the Balcarce Formation is considered here to be Ordovician to Silurian in age. The Balcarce Formation can be correlated with similar rocks in South Africa, the Peninsula Formation, and the upper Table Mountain Group (Windhoek and Nardouw subgroups), including the Hirnantian glacial deposit of the Pakhuis Formation.     

Zircon megacrysts from basalts of the Venetian Volcanic Province (NE Italy): U–Pb ages, oxygen isotopes and REE data

Mafic alkaline lavas from the Venetian Volcanic Province (NE Italy) contain orange–brown zircon megacrysts up to 15 mm long, subhedral to subrounded and showing equant morphology, with width-to-length ratios of 1:2–1:2.5. U–Pb ages of zircon (51.1 ± 1.5 to 30.5 ± 0.51 Ma) fit the stratigraphic age of the host lava (Middle Eocene and Oligocene) and their oxygen isotope composition (δ¹⁸O = 5.31–5.51‰) is similar to that of zircon formed in the upper mantle. Cathodoluminescence images and crystal chemical features, e.g. depletion of incompatible elements such as REE, Y, U and Th at constant Hf content, indicate that centre-to-edge zircon zoning is not consistent with evolution of the melt by fractional crystallization. All the above features, together with the fact that zircon and host basalts are coeval, indicate that the studied Zr megacrysts crystallised from a primitive alkaline mafic magma, which later evolved to the less alkaline host magma.     

An objective method to rank the importance of the factors predisposing to landslides with the GIS methodology: application to an area of the Apennines (Valnerina; Perugia, Italy)

The present work aims at contributing to further our knowledge on the predisposing factors to landslides as well as proposing a method that allows us to weigh up, as objectively as possible, the influence that the various factors have on landslides in order to construct a realistic map of potential landslide hazards. In order to assess the differential incidence of very predisposing factor to landslides, maps of the various factors considered were drawn up with the aid of IDRISI software (1997). The factors were as follows: the distance from faults, parallelism between the fractures and the landslide scarps, land use, lithology, distance from the streams, orientation and steepness of slopes, orientation of layers compared to the slope. The global analysis of the different incidence of the factors analyzed on the landslides present in the study area was carried out by comparing the respective maps with that of the scarps; in this way the number of pixels forming the scarps which fell into the various classes of the maps was calculated. The result thus obtained can form the basis of an objective assignation of the different ratings to be attributed to the various factors under consideration. In fact, the analysis carried out in this study has shown that the factors act differently and, for every factor, only some of the classes considered have marked importance.     

The Role of Data Processing and Uncertainty Management in Seismic Hazard Evaluations: Insights from Estimates in the Garfagnana–Lunigiana Area (Northern Italy)

Significantly different estimates of seismic hazard may result for the same site as aneffect of different methodological choices underlying the adopted procedures. In orderto explore this aspect, two approaches devoted to probabilistic seismic hazard assessment are considered for the evaluation of hazard in a seismic area in Northern Italy. In particular, results of a standard procedure are compared with those obtained by an innovative approach. Fundamental features of this last methodology are the extensive use of intensity data relative to seismic effects observed at the site of interest during past earthquakes and the basic role attributed to the parameterisation of uncertainty which affects the considered pieces ofinformation. The analysis indicates that the new approach supplies results significantlydifferent from those obtained from standard methodology and that these differences strongly depend on strategies adopted for data processing and for the management of uncertainties which affect input parameters.     

Magnetic and ground probing radar measurements for soil pollution mapping in the industrial area of Val Basento (Basilicata Region, Southern Italy): a case study

The joint application of electromagnetic techniques for near-surface exploration is a useful tool for soil pollution monitoring and can also contribute towards describing the spatial distribution of pollutants. The results of a geophysical field survey that was carried out for characterizing the heavy metal and waste disposal soil pollution phenomena in the industrial area of Val Basento (Basilicata region, Southern Italy) are presented here. First, topsoil magnetic susceptibility measurements have been carried out for defining the spatial distribution of superficial pollution phenomena in the investigated area. Second, detailed and integrated measurements based on a high-resolution magnetic mapping and ground probing radar (GPR) profiling have been applied to investigate the subsurface in two industrial areas located in more polluted sites that were identified during the first phase. Our monitoring strategy discloses the way to rapidly define the zone characterized by high pollution levels deriving from chemical industries and traffic emissions and to obtain the way information about the presence of local buried sources of contamination.     

Evaluating Bayesian Radiocarbon-dated Event Count (REC) models for the study of long-term human and environmental processes

Chronological uncertainty complicates attempts to use radiocarbon dates as proxies for processes such as human population growth/decline, forest fires and marine ingression. Established approaches involve turning databases of radiocarbon-date densities into single summary proxies that cannot fully account for chronological uncertainty. Here, I use simulated data to explore an alternative Bayesian approach that instead models the data as what they are, namely radiocarbon-dated event counts. The approach involves assessing possible event-count sequences by sampling radiocarbon date densities and then applying a Markov Chain Monte Carlo method to estimate the parameters of an appropriate count-based regression model. The regressions based on individual sampled sequences were placed in a multilevel framework, which allowed for the estimation of hyperparameters that account for chronological uncertainty in individual event times. Two processes were used to produce simulated data. One represented a simple monotonic change in event-counts and the other was based on a real palaeoclimate proxy record. In both cases, the method produced estimates that had the correct sign and were consistently biased towards zero. These results indicate that the approach is widely applicable and could form the basis of a new class of quantitative models for use in exploring long-term human and environmental processes.     

Fissumella motolae n. gen. n. sp., a new soritoidean (Foraminifera) from the lowermost Albian carbonate platform facies of central and southern Italy

The Soritoidea (Foraminifera) represent an important component of Cenomanian microfossil assemblages of the central and southern Tethyan carbonate platforms and are widely used as biostratigraphic markers. In this paper a new taxon, Fissumella motolae n. gen. n. sp., is described from the Cretaceous carbonate platform facies of central and southern Italy. It is characterized by its small size, planispiral-involute arrangement of chambers, fissure-shaped single aperture and few and short radial septula subdividing the marginal lumen of the chambers. Fissumella motolae n. gen. n. sp. represents the first soritoidean in the fossil record showing internal subdivisions of the chamber lumen. Carbon isotope stratigraphy supports an earliest Albian age for this significant step in the evolution of the superfamily Soritoidea. The new subfamily Fissumellinae is established for soritoidean foraminifera with planispiral-involute lens-shaped shells, single aperture and chamber lumen subdivided by few and short septula.     

Perched lobe formation in the Gulf of Cadiz: Interactions between gravity processes and contour currents (Algarve Margin, Southern Portugal)

The Gulf of Cadiz is swept by the strong saline Mediterranean Outflow Water (MOW). On the Algarve Margin (South Portugal), this current has constructed fine-grained contourite drifts. This margin is dissected by the Portimao Canyon and three short channels that only incise the upper slope, and are absent on a terrace located at mid-slope depths along the Algarve Margin. High-resolution seismic profiles and sediment cores highlight the original architecture of the sedimentary deposits on this terrace. Coarse-grained lenticular chaotic bodies formed during major relative sea-level lowstands are intercalated within the drift. The lobate shape and sandy nature of the lenticular chaotic bodies and their location at the mouths of the three short channels suggest they are gravity-generated deposits that are perched on the middle continental slope.In the Gulf of Cadiz, the interaction between contour current and gravity processes is strongly controlled by climatic variations and relative sea-level changes during the late Quaternary. During cold periods when sea-level was low, erosion intensified on the continental shelf and the deepest part of MOW was active. Sediment was transported downslope through the channels and deposited on sedimentary lobes perched on the mid-slope terrace. During warm periods when relative sea-level was high, the supply of sediment from the shelf was shut off and the shallowest part of MOW was more active. Contourite drifts fill the channels and bury the sandy lobes.     

云南二叠纪白马寨铜镍硫化物矿床的成因:地壳混染与矿化的关系

云南金平白马寨-营盘街-带的奥陶纪变砂岩和板岩中出露大量小型约260Ma的镁铁-超镁铁质岩体,其中白马寨地区三个岩体具明显铜-镍硫化物矿化：三号岩体有一个中型铜镍硫化物矿床,一号和二号岩体可见微弱矿化。一号岩体的Ni／Cu值为0．7～2．2,二号岩体的Ni／Cu值为1．4～4．0,与三号岩体的比值（Ni／Cu=-0．5～6．7）相近,说明他们的母岩浆成分接近,为富Mg的镁铁质或苦橄质岩浆。三个岩体遭受不同程度的地壳混染,表现为强烈的Nb（Ta）异常,很低的Nb／La值（O．5～O．7）和很负的￡。。（f）值（一5．1～一9．O）。根据全岩的Th／Yb和Nb／Th值估算,一号岩体的地壳混染程度为5％～20％,二号岩体的地壳混染程度为5％～10％,而三号岩体的地壳混染程度高达35％。三个岩体的地壳混染程度与岩体中硫化物的含量呈正相关关系,表明地壳混染是导致白马寨岩体硫化物饱和的主要因素。     

全球气候研究计划 (WCRP)中的气候与冰冻圈项目 (CliC): 冰冻圈与气候的优先研究领域

The cryosphere is an integral part of the global climate system, however, many aspects of the cryosphere have not been fully covered within WCRP. Issues relating to potential changes in the climate cryosphere system become more and more important in order to describes research and coordination initiatives required to integrate fully studies of impact and response of the cryosphere to climate change. The article also indicates the recent progress of CliC, and its future plan.     

Women and the access to knowledge and new technologies: The case of Pisa

Emphasis has been given to a number of aspects which characterise technological development in today's economic systems and which have an impact on the working environment and on gender differences. Technological change is leading to a strong divide between knowledge “producers” and “users”. The possibility of access to one or both knowledge systems indicates the extent of women's participation in the economic and spatial transformations brought about by the new technologies. This research aims to analyse the development of new technologies and the presence of the female workforce in the field of new knowledge generation, and also to verify gender-related conditions in learning and using new technologies. In particular, an analysis has been carried out of the empirical case study of Pisa, a point of reference for comparisons with other Italian and European cases. The research focuses on: the examination of women's capabilities in the field of new technologies through the analysis of University training courses; the analysis of women's presence and status among the university staff, especially in science and technology; a detailed survey of female employment in innovative sectors. The results of the research emphasise the gender perspectives of inclusion — as regards the application of technologies — and exclusion — as regards the generation of knowledge — of women in or from new technologies. At the same time, the research stresses the growth of women's roles in this sector during recent years and, by reconstructing life histories, underlines the conditions and difficulties that have been met by women entering these new types of employment. This revised version was published online in July 2006 with corrections to the Cover Date.     

Petrology and mineralogy of granulite-facies mafic xenoliths (Sardinia, Italy): Evidence for KCl metasomatism in the lower crust

Here new mineralogical data is presented on the occurrence of K-feldspar in granulite-facies metagabbronorite xenoliths found in recent alkaline lavas from Western Sardinia, Italy. The xenoliths originated from the underplating of variably evolved subduction-related basaltic liquids, which underwent cooling and recrystallisation in the deep crust (T = 850–900 °C, P = 0.8–1.0 GPa). They consist of orthopyroxene + clinopyroxene + plagioclase porphyroclasts (An = 50–66 mol%) in a granoblastic, recrystallised, quartz-free matrix composed of pyroxene + plagioclase (An = 56–72 mol%) + Fe–Ti oxides ± K-feldspar ± biotite ± fluorapatite ± Ti-biotite. Texturally, the K-feldspar occurs in a variety of different modes. These include: (1) rods, blebs, and irregular patches in a random scattering of plagioclase grains in the form of antiperthite; (2) micro-veins along plagioclase–plagioclase and plagioclase–pyroxene grain rims; (3) myrmekite-like intergrowths with Ca-rich plagioclase along plagioclase–plagioclase grain boundaries; and (4) discrete anhedral grains (sometimes microperthitic). The composition of each type of K-feldspar is characterized by relatively high albite contents (16–33 mol%). An increasing anorthite content in the plagioclase towards the contact with the K-feldspar micro-vein and myrmekite-like intergrowths into the K-feldspar along the plagioclase–K-feldspar grain boundary are also observed. Small amounts of biotite (TiO₂ = 4.7–6.5 wt.%; F = 0.24–1.19 wt.%; Cl = 0.04–0.20 wt.%) in textural equilibrium with the granulite-facies assemblage is present in both K-feldspar-bearing and K-feldspar-free xenoliths. These K-feldspar textures suggest a likely metasomatic origin due to solid-state infiltration of KCl-rich fluids/melts. The presence of such fluids is supported by the fluorapatite in these xenoliths, which is enriched in Cl (Cl = 6–50% of the total F + Cl + OH). These lines of evidence suggest that formation of K-feldspar in the mafic xenoliths reflects metasomatic processes, requiring an external K-rich fluid source, which operated in the lower crust during and after in-situ high-T recrystallisation of relatively dry rocks.     

Assessing Possibilities and Limitations for Biomarker Analyses on Outcrop Samples: A Case Study on Carbonates of the Shibantan Member (Ediacaran Period,Dengying Formation,South China)

Abstract: The Shibantan Member (Dengying Formation, South China) represents one of only two carbonate settings with Ediacara-type organisms and offers a rare opportunity to study the biogeochemistry of these ecosystems. To evaluate possibilities and limitations for future biomarker studies on fossil-bearing outcrop samples of the Shibantan Member, we analysed the spatial distribution of hydrocarbons in extractable organic matter (i.e. bitumen) on a millimetre scale. Our study demonstrates that the sample and most likely also other rocks from the same setting are contaminated with petroleum-derived compounds that bear the potential for erroneous interpretations in palaeo-reconstructions. The contamination was revealed by distribution patterns and amounts of extractable n-alkanes and acyclic isoprenoids. The contamination is linked to the external weathering surfaces but also to cracks within the rock, and the extent most likely depends on concentration gradients between these contamination sources. Here we show that contamination can successfully be distinguished from syngenetic signals obtained from non-extractable organic matter (i.e. kerogen) using catalytic hydropyrolysis (HyPy). However, we observed that decalcification is necessary to achieve sufficient yields of kerogen-bound hydrocarbons and to avoid artificial alteration of the biomarker signals due to matrix effects.     

东秦岭160～140Ma Cu(Mo)和Mo(W)成矿作用的差异性:来自成矿岩体的地球化学及其岩浆源区的证据

东秦岭地区在商丹断裂带南北两侧分别形成了矽卡岩-斑岩型Cu(Mo)矿床和斑岩-矽卡岩型Mo(W)矿床,两者均形成于160~140Ma。通过对不同矿床的地质特征和成矿岩体对比研究发现,Mo(W)矿床主要分布在商丹断裂带北侧的北秦岭和华北板块南缘,主要分布有新太古代至奥陶纪地层,由一系列变质程度不同的火山岩和沉积岩组成。Cu(Mo)矿床主要位于商丹断裂带南侧的南秦岭晚古生代弧前盆地,主要分布古生代地层,由粉砂岩、绢云板岩、灰岩、杂砂岩及白云岩等组成。Mo(W)矿床的成矿岩体以花岗斑岩为主,具有高硅、富钾,贫镁铁,较高的岩浆分异程度;Cu(Mo)矿床的成矿岩体以花岗闪长斑岩为主,具有低硅、低钾,富镁铁,低分异的特征。Mo(W)成矿岩体亏损Ba,富集U、Nb等元素,Cu(Mo)成矿岩体相对富集Ba,亏损U、Nb等元素;Cu(Mo)成矿岩体∑REE略高于Mo(W)成矿岩体,未表现出明显的Eu异常,而Mo(W)成矿岩体具有负Eu异常。Cu(Mo)和Mo(W)成矿岩体具有相似的结晶温度,Mo(W)成矿岩体具有相对较高的形成压力和氧化态。Mo(W)成矿岩体的岩浆源区以辉石为残留相,Cu(Mo)成矿岩体的岩浆源区则是以极少量角闪石为残留相。相对于Mo(W)矿床,Cu(Mo)矿床的成矿岩体具有较高的εNd(t)值(-28.8~-12.1和-4.75~-2.73)和εHf(t)值(-38~-7.9和-3.79~+1.79),这说明Cu(Mo)成矿岩体的岩浆源区中含有相对较多的地幔物质,而Mo(W)成矿岩体的岩浆源区中含有相对较多地壳物质。由于两种矿化位于不同的构造单元以及成矿岩体在岩石地球化学、温压条件、氧化还原状态和岩浆源区特征等方面的差异造成了160~140Ma岩浆活动在商丹断裂带南北两侧形成不同矿化类型。     

Thermal and tectonic evolution of the southern Alps (northern Italy) rifting: Coupled organic matter maturity analysis and thermokinematic modeling

The Pearl River Mouth Basin (PRMB) is one of the most petroliferous basins on the northern margin of the South China Sea. Knowledge of the thermal history of the PRMB is significant for understanding its tectonic evolution and for unraveling its poorly studied source-rock maturation history. Our investigations in this study are based on apatite fission-track (AFT) thermochronology analysis of 12 cutting samples from 4 boreholes. Both AFT ages and length data suggested that the PRMB has experienced quite complicated thermal evolution. Thermal history modeling results unraveled four successive events of heating separated by three stages of cooling since the early Middle Eocene. The cooling events occurred approximately in the Late Eocene, early Oligocene, and the Late Miocene, possibly attributed to the Zhuqiong II Event, Nanhai Event, and Dongsha Event, respectively. The erosion amount during the first cooling stage is roughly estimated to be about 455–712 m, with an erosion rate of 0.08–0.12 mm/a. The second erosion-driven cooling is stronger than the first one, with an erosion amount of about 747–814 m and an erosion rate between about 0.13–0.21 mm/a. The erosion amount calculated related to the third cooling event varies from 800 m to 3419 m, which is speculative due to the possible influence of the magmatic activity.     

Metacarbonate-terrigenous complex of the Derba block (East Sayan): petrogeochemical and isotope parameters,metamorphism, and time of formation

The Derba block is one of the largest Precambrian terranes of the Sayan-Yenisei accretionary belt in the southwestern margin of the Siberian Platform. It is composed of metamorphosed terrigenous-carbonate rocks of the Sayan Group, injected by granitoids. The geochemical features of gneiss-schist associations indicate the low maturity of their sedimentary protoliths corresponding in composition mainly to graywackes and terrigenous-carbonate rocks (marls). According to the results of U-Pb (LA-ICP-MS) dating of detrital zircons from gneisses and schists, the sedimentary protolith formed in the Vendian. Neoproterozoic subduction complexes were probably the major provenance for terrigenous material, and Early Precambrian rocks made a limited contribution. The Ar-Ar and U-Pb isotope data testify to nearly coeval and multistage events of metamorphism (up to the amphibolite facies) and granitoid magmatism (~ 510-500 and 480-465 Ma) in the Derba block. These processes were reflective of the Early Caledonian orogenic processes in the structures of the Central Asian Orogenic Belt. The similarity in the composition, time of sedimentation, and provenances of metaterrigenous-carbonate complexes of the Derba block (Sayan Group), West Sangilen block of the Tuva-Mongolian massif (Erzin and Moren complexes), and the Khamar-Daban terrane (Slyudyanka Group) suggests that these structures were a single Vendian continental margin with lateral variations in depositional environments and the sources of terrigenous material.