Petrogenesis of granitic unit of Naqadeh complex, Sanandaj–Sirjan Zone, NW Iran

The granitic unit is a component of the Naqadeh plutonic complex, NW of Sanandaj–Sirjan Zone (NW Iran). This unit is composed of high-K calc-alkaline, slightly peraluminous (ASI?=?1.12–1.17) evolved monzogranites. These monzogranites have 41.85?±?0.81 Ma (zircon U–Pb sensitive, high-resolution ion microprobe (SHRIMP) age) with two inherited zircon ages of 98.5?±?1.7 and 586.6?±?13.1 Ma, respectively. The only enclave type consists of quartz-amphibolite enclaves indicating residual parental rocks. Chemical and isotopic (⁸⁷Sr/⁸⁶Sr_40Ma?=?0.708638; εNd_40Ma?=??4.26) characteristics of monzogranites suggest that they could be derived by partial melting of crustal mafic rocks followed by some assimilation of metasedimentary rocks. With regards to inherited zircon age and quartz-amphibolite composition of Naqadeh granite, the old mafic rocks of this complex (Naqadeh dioritic rocks with ~100 Ma) can be considered as parental rocks, and their partial melting under high water content, and assimilation of produced melt by metasedimentary rocks, would lead to the generation of a Naqadeh granitic unit.     

Comparative study between filtering and inversion of VLF-EM profile data

This paper discusses the practical use of filtering and inversion in VLF-EM data processing and interpretation. The advantages and disadvantages of both mentioned techniques were outlined to avoid the misleading interpretation of such data in some case studies. Much concern is taken to show the interval distance effect upon the correct depth identification of the anomalous body by either inversion or filtering. The methodology of the study is going through proposing an initial model, generating the synthetic VLF-EM data of the model by means of forward modeling, filtering (Karous–Hjelt filter) and inversion (Inv2DVLF software) of the synthetic data and comparing between the results of both methods and the initial model. The study reached to (1) Karous–Hjelt filter provides misleading depths for his limited depth of resolution and cannot provide estimates of deep targets if the profile is too small, whereas inversion provides exact results, particularly in case of shallow anomalous target; (2) crossover between in-phase and out-of-phase data could resulted from a small shallow conductive target or a large deep one; (3) selection of a reasonable environmental resistivity has an important impact on the inversion process; and (4) the numerical reflection resulted during VLF-EM data inversion could lead to an erroneous interpretation.     

A hybrid efficient method to downscale wave climate to coastal areas

Long-term time series of sea state parameters are required in different coastal engineering applications. In order to obtain wave data at shallow water and due to the scarcity of instrumental data, ocean wave reanalysis databases ought to be downscaled to increase the spatial resolution and simulate the wave transformation process. In this paper, a hybrid downscaling methodology to transfer wave climate to coastal areas has been developed combining a numerical wave model (dynamical downscaling) with mathematical tools (statistical downscaling). A maximum dissimilarity selection algorithm (MDA) is applied in order to obtain a representative subset of sea states in deep water areas. The reduced number of selected cases spans the marine climate variability, guaranteeing that all possible sea states are represented and capturing even the extreme events. These sea states are propagated using a state-of-the-art wave propagation model. The time series of the propagated sea state parameters at a particular location are reconstructed using a non-linear interpolation technique based on radial basis functions (RBFs), providing excellent results in a high dimensional space with scattered data as occurs in the cases selected with MDA. The numerical validation of the results confirms the ability of the developed methodology to reconstruct sea state time series in shallow water at a particular location and to estimate different spatial wave climate parameters with a considerable reduction in the computational effort.     

Variations in some physico-chemical parameters in a hypersaline coastal lagoon of Baja California,Mexico

San Jose lagoon is a hypersaline body of water located in Mexico in the Baja California Peninsula. The lagoon belongs to a system that lies between the fault ridge known as San Jose Creek. Because of its marine origin, it can be considered as thalassohaline, but its isolation from the ocean has brought about changes in its salt composition. It has an area of 13,500 m², a mean depth of 80 cm and a total volume of 10,000 m³. It does not desiccate and can be considered as a permanent lagoon. Seasonal variations are small. TheArtemia population in San Jose produces cysts all year. To determine the physico-chemical conditions inducing permanent production of cysts, temperature, salinity, dissolved oxygen, and pH of the lagoon were monitored, as well as relative humidity and wind conditions in the region in different seasons of the year. From spring to summer, differences of 1 mg L^–1 of O₂, 1°C in water temperature, and 8 g L^–1 in salinity were observed, and from summer to winter differences of 3.3 mg L^–1, 6.5°C, and 14 g L^–1, respectively. Despite small seasonal variations, the lagoon exhibits strong spatial and daily changes that are important for cyst production.     

A general framework for assessing potential seismic risk in geotechnical projects

Summary In this paper a general framework is discussed for assessing the seismicity and the seismic risk using a couple-information model. A deterministic model is used to define the different types of information that can represent the input variables of the model; that is, constants, random, fuzzy, linguistic, hybrid and chaotic variables. Other types of models are also discussed having information similar to the input variables, and a way is presented to implement them for assessing risk.     

Velocity structure of upper-mantle transition zones beneath central eurasia from seismic inversion using genetic algorithms

We present velocity constraints for the upper-mantle transition zones beneath Central Siberia based on observations of the 1982 RIFT Deep Seismic Sounding (DSS) profile. The data consist of seismic recordings of a nuclear explosion in north-western Siberia along a 2600 km long seismic profile extending from the Yamal Peninsula to Lake Baikal. We invert seismic data from the mantle transition zones using a non-linear inversion scheme using a genetic algorithm for optimization and the WKBJ method to compute the synthetic seismograms. A statistical error analysis using a graph-binning technique was performed to provide uncertainty values in the velocity models.
Our best model for the upper-mantle velocity discontinuity near 410 km depth has a two-stage velocity-gradient structure, with velocities increasing from 8.70–9.25 km s⁻¹ over a depth range of 400–415 km, a gradient of 0.0433 s⁻¹, and from 9.25–9.60 km s⁻¹ over a depth range of 415–435 km, a gradient of 0.0175 s⁻¹. This derived model is consistent with other seismological observations and mineral-physics models. The model for the velocity discontinuity near 660 km depth is simple, sharp and includes velocities increasing from 10.15 km s⁻¹ at 655 km depth to 10.70 km s⁻¹ at 660 km depth, a gradient of 0.055 s⁻¹.     

Tectonic and oceanographic control of sedimentary patterns in a small oceanic basin: Dove Basin (Scotia Sea,Antarctica)

Dove Basin, a small oceanic domain located within the southern Scotia Sea, evidences a complex tectonic evolution linked to the development of the Scotia Arc. The basin also straddles the junction between the main Southern Ocean water masses: the Antarctic Circumpolar Current (ACC), the Southeast Pacific Deep Water (SPDW) and the Weddell Sea Deep Water (WSDW). Analysis of multichannel seismic reflection profiles, together with swath bathymetry data, reveals the main structure and sediment distribution of the basin, allowing a reconstruction of the tectonostratigraphic evolution of the basin and assessment of the main bottom water flows that influenced its depositional development. Sediment dispersed in the basin was largely influenced by gravity‐driven transport from adjacent continental margins, later modified by deep bottom currents. Sediments derived from melting icebergs and extensive ice sheets also contributed to a fraction of the basin deposits. We identify four stages in the basin evolution which – based on regional age assumptions – took place during the early Miocene, middle Miocene, late Miocene–early Pliocene and late Pliocene–Quaternary. The onsets of the ACC flow in Dove Basin during the early Miocene, the WSDW flow during the middle Miocene, and the SPDW during the late Miocene were influenced by tectonic events that facilitated the opening of new oceanic gateways in the region. The analysis of Dove Basin reveals that tectonics is a primary factor influencing its sedimentary stacking patterns, the structural development of new oceanic gateways permitting the inception of deep‐water flows that have since controlled the sedimentary processes.     

On Dry Deposition Modelling of Atmospheric Pollutants on Vegetation at the Microscale: Application to the Impact of Street Vegetation on Air Quality

A Reynolds-averaged Navier–Stokes model is used to investigate the impact of urban canopy vegetation on air quality, with particular emphasis on the comparison between the positive effect induced by deposition versus the negative effect due to a reduction of ventilation. With this aim, a series of simulations over a simplified urban geometry with different vegetation designs are carried out. The problem is tackled at two scales. From the mesoscale point of view, the relevant variable is the total deposition flux of pollutant as a function of the pollutant concentration above the canopy (e.g. the “mesoscale” deposition velocity). This is assessed within the Monin–Obukov similarity theory framework, and a modification of the classical formulation is proposed based on the numerical results. At the microscale, the distribution of concentration within the urban canopy is investigated for the different configurations. The main conclusion is that the height of the vegetation and the magnitude of the microscale deposition velocity are key parameters that determine which of the two effects (deposition or reduction of ventilation) prevails.