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91.
New data on ophiolite-bearing terranes of the Liguride Complex, together with some information on the terranes of the Sicilide Complex, result in a better understanding of the role and tectonic significance of these units in the construction of the Southern Apennines orogenic belt. The Liguride Complex is composed of two main tectonic units overlain by a thick turbiditic sequence of Late Oligocene-Middle Miocene age. The uppermost one (Frido Unit) is a polydeformed and polymetamorphosed sequence, composed of two tectonic subunits of shales and calc-schists, respectively, containing blocks of ophiolite, garnet gneiss, amphibolites and granitoids. This unit is thrust over the un-metamorphosed terranes (Calabro–Lucano Flysch Unit) consisting of a broken formation with blocks of Late Jurassic ophiolite and their sedimentary cover, Cretaceous-Eocene pelagic sediments and Late Oligocene volcaniclastic deposits. The Frido Unit underwent HP/LT metamorphism (P= 8–10 Kb; T= 400–500 °C) resulting in glaucophane and lawsonite assemblages in the ophiolitic rocks and aragonite in the meta-limestones and calc-schists, followed by greenschist fades metamorphism (P= 4 Kb; T= 300–350 °C). From a structural point of view units of the Liguride Complex comprise structures developed at different structural levels, indicating progressive non-coaxial deformation in response to tectonic transport towards the N-NE. The ophiolite-bearing terranes of the Liguride Complex can be considered as a remnant of an accretionary complex in which the Calabro Lucano Flysch Unit represents the toe of the wedge where frontal accretion processes occur and the Frido Unit is a deeper portion. Emplacement of the Frido Unit is explained as being due to formation of a deep duplex structure during the early stage of continental collision processes. The polarity of tectonic transport provides new evidence that the Liguride Complex represents a suture zone between the Apulian and the Calabrian blocks. The age of collision appears to be not older than late Oligocene. The allochtonous terranes of the Liguride and Sicilide Complexes, therefore, represent a complete accretionary wedge which records, first, subduction of the Neotethys ocean beneath the Calabrian (Europe) continental margin and, later, continental collision with the African block. 相似文献
92.
The D'Alembert model for the spin/orbit problem in celestial mechanics is considered. Using a Hamiltonian formalism, it is shown that in a small neighborhood of a p:q spin/orbit resonance with (p,q) different from (1,1) and (2,1) the 'effective' D'Alembert Hamiltonian is a completely integrable system with phase space foliated by maximal invariant curves; instead, in a small neighborhood of a p:q spin/orbit resonance with (p,q) equal to (1,1) or (2,1) the 'effective' D'Alembert Hamiltonian has a phase portrait similar to that of the standard pendulum (elliptic and hyperbolic equilibria, separatrices, invariant curves of different homotopy). A fast averaging with respect to the 'mean anomaly' is also performed (by means of Nekhoroshev techniques) showing that, up to exponentially small terms, the resonant D'Alembert Hamiltonian is described by a two-degrees-of-freedom, properly degenerate Hamiltonian having the lowest order terms corresponding to the 'effective' Hamiltonian mentioned above. 相似文献
93.
94.
Response of the bacterial community to in situ bioremediation of organic-rich sediments 总被引:8,自引:0,他引:8
A field trial experiment was carried out to assess the potential of bioremediation for mobilisation of carbon in organic-rich sediments. Both bioaugmentation (bio-fixed microorganisms) and biostimulation (oxygen release compounds--ORC) protocols have been tested and the response of the bacterial community has been described to assess the baseline for bioremediation potential. Multifactorial ANOVA revealed that bioaugmentation protocol had an effect in stimulate mobilisation processes and significantly enhanced extra-cellular enzymatic activity rates. In contrast biostimulation treatment did not have an effect on mobilisation rates but contributed to enhance bacterial efficiency through a maximization of the bacterial production:enzymatic activity ratio. Average calculation of net mobilised carbon showed that 23% increase of mobilised pool was accounted for bioaugmentation in summer. Although biostimulation accounted for a smaller increase in mobilised carbon (<10%), the use of ORC resulted in an increased mineralisation and net carbon loss via respiration. Based on our results, a conceptual model for application of bioremediation to face the problem of sediment eutrophication is discussed. 相似文献
95.
Cristina?PerinelliEmail author Pietro?Armienti Luigi?Dallai 《Contributions to Mineralogy and Petrology》2006,151(3):245-266
Peridotite xenoliths found in Cenozoic alkali basalts of northern Victoria Land, Antarctica, vary from fertile spinel-lherzolite
to harzburgite. They often contain glass-bearing pockets formed after primary pyroxenes and spinel. Few samples are composite
and consist of depleted spinel lherzolite crosscut by amphibole veins and/or lherzolite in contact with poikilitic wehrlite.
Peridotite xenoliths are characterized by negative Al2O3–Mg# and TiO2–Mg# covariations of clino- and orthopyroxenes, low to intermediate HREE concentrations in clinopyroxene, negative Cr–Al trend
in spinel, suggesting variable degrees of partial melting. Metasomatic overprint is evidenced by trace element enrichment
in clinopyroxene and sporadic increase of Ti–Fetot. Preferential Nb, Zr, Sr enrichments in clinopyroxene associated with high Ti–Fetot contents constrain the metasomatic agent to be an alkaline basic melt. In composite xenoliths, clinopyroxene REE contents
increase next to the veins suggesting metasomatic diffusion of incompatible element. Oxygen isotope data indicate disequilibrium
conditions among clinopyroxene, olivine and orthopyroxene. The highest δ18O values are observed in minerals of the amphibole-bearing xenolith. The δ18Ocpx correlations with clinopyroxene modal abundance and geochemical parameters (e.g. Mg# and Cr#) suggest a possible influence
of partial melting on oxygen isotope composition. Thermobarometric estimates define a geotherm of 80°C/GPa for the refractory
lithosphere of NVL, in a pressure range between 1 and 2.5 GPa. Clinopyroxene microlites of melt pockets provide P–T data close
to the anhydrous peridotite solidus and confirm that they originated from heating and decompression during transport in the
host magma. All these geothermometric data constrain the mantle potential temperature to values of 1250–1350°C, consistent
with the occurrence of mantle decompressional melting in a transtensive tectonic regime for the Ross Sea region. 相似文献
96.
Jessica R. Rodysill James M. Russell Satria Bijaksana Erik T. Brown La Ode Safiuddin Hilde Eggermont 《Journal of Paleolimnology》2012,47(1):125-139
Variations in the location and strength of convection in the Western Pacific Warm Pool (WPWP) have a profound impact on the
distribution and amount of global rainfall. Much of the variability in WPWP convection is attributed to variations in the
El Ni?o-Southern Oscillation, for which the long-term trends and forcing mechanisms remain poorly understood. Despite the
importance of WPWP convection to global climate change, we have very few paleohydrological reconstructions from the region.
Here we present a new paleolimnologic and paleohydrologic record spanning the past 1,400 years using a multi-proxy dataset
from Lake Logung, located in East Java, Indonesia that provides insights into centennial-scale trends in warm pool hydrology.
Organic matter δ13C data indicate that East Java became wetter over the last millennium until ca. 1800 Common Era (CE), consistent with evidence
for the southward migration of the Intertropical Convergence Zone (ITCZ) during this time. Superimposed on this long-term
trend are four decade- to century-scale droughts, inferred from organic matter δ13C and calcite abundance data. They are centered at 1030, 1550, 1830, and 1996 CE. The three more recent droughts correlate
with hydrologic anomalies documented in other proxy records from the WPWP region on both sides of the equator, and the two
most recent droughts correlate in time with historically documented periods of multiple, intense El Ni?o events. Thus, our
record provides strong evidence that century-scale hydrologic variability in this region relates to changes in the Walker
Circulation. Human activity within the lake catchment is apparent since 1860 CE. 相似文献
97.
Relative sea level rise (RSLR) due to climate change and geodynamics represents the main threat for the survival of Venice,
emerging today only 90 cm above the Northern Adriatic mean sea level (msl). The 25 cm RSLR occurred over the 20th century,
consisting of about 12 cm of land subsidence and 13 cm of sea level rise, has increased the flood frequency by more than seven
times with severe damages to the urban heritage. Reasonable forecasts of the RSLR expected to the century end must be investigated
to assess the suitability of the Mo.S.E. project planned for the city safeguarding, i.e., the closure of the lagoon inlets
by mobile barriers. Here we consider three RSLR scenarios as resulting from the past sea level rise recorded in the Northern
Adriatic Sea, the IPCC mid-range A1B scenario, and the expected land subsidence. Available sea level measurements show that
more than 5 decades are required to compute a meaningful eustatic trend, due to pseudo-cyclic 7–8 year long fluctuations.
The period from 1890 to 2007 is characterized by an average rate of 0.12 ± 0.01 cm/year. We demonstrate that linear regression
is the most suitable model to represent the eustatic process over these 117 year. Concerning subsidence, at present Venice
is sinking due to natural causes at 0.05 cm/year. The RSLR is expected to range between 17 and 53 cm by 2100, and its repercussions
in terms of flooding frequency are associated here to each scenario. In particular, the frequency of tides higher than 110 cm,
i.e., the value above which the gates would close the lagoon to the sea, will increase from the nowadays 4 times per year
to a range between 20 and 250. These projections provide a large spread of possible conditions concerning the survival of
Venice, from a moderate nuisance to an intolerable aggression. Hence, complementary solutions to Mo.S.E. may well be investigated. 相似文献
98.
99.
Luigi Sambuelli 《Rock Mechanics and Rock Engineering》2009,42(3):547-556
I would like to suggest a theoretical justification for the mathematical structure of some laws for predicting the maximum
particle velocity vibration from blasting operations in the light of some basic notions of elastic and anelastic wave theory.
Within this point of view, in dimensionally correct expressions, the terms pertaining to the rock, to the blast and to the
seismic wave become evident and recognisable. A law is presented that can be used to forecast the maximum particle velocity
on the basis of some blast design and rock parameters. Four tests of the proposed law performed with real data sets seem to
confirm fairly well its reliability. 相似文献
100.
In this paper we describe a new computing system array, designed, built and now used at the Space Astrophysics and Planetary Institute (IAPS) in Rome, Italy, for the INTEGRAL Space Observatory scientific data analysis. This new system has become necessary in order to reduce the processing time of the INTEGRAL data accumulated during the more than 9 years of in-orbit operation. In order to fulfill the scientific data analysis requirements with a moderately limited investment the starting approach has been to use a ??cluster?? array of commercial quad-CPU computers, featuring the extremely large scientific and calibration data archive on line. 相似文献