The Miduk porphyry Cu deposit,Kerman, Iran: A geochemical analysis of the potassic zone including halogen element systematics related to Cu mineralization processes

Miduk hypogene and supergene porphyry Cu–Mo mineralization occurs within the Miocene porphyritic quartz–diorite and host Eocene plagioclase–hornblende phyric andesitic pyroclastic and flow sequence. Both the host rocks were extensively altered by hydrothermal fluids to dominantly potassic, phyllic, and argillic with interstitial to distal propylitic types.     

Convergent development of experimental landforms with differing rainfall and substrate properties

Four runs of experimental landform development, with the same uplift rate, different rainfall intensity, and the same material of different permeability adjusted by the degree of compaction, showed complicated effects of rainfall and mound-forming material. In the run with more rainfall on less permeable material, low separated ridges developed in the uplifted area, because abundant overland flow promoted valley erosion and slope processes from early stages. In the run with less rainfall on less permeable material, valley incision proceeded mostly in major valleys where surface water converges. Canyons developed during early stages and later a high massive mountain emerged. The effect of rainfall difference, however, appeared completely opposite on more permeable material accompanied by lower shear strength. In the run with more rainfall on more permeable material, a massive mountain similar to that with less rainfall on less permeable material appeared, and low separated ridges appeared in the run with less rainfall on more permeable material as in the run with more rainfall on less permeable material. In the former case, similar amount of water available for Hortonian overland flow in early stages estimated from rainfall rate and permeability can explain the development of similar landforms. In the latter case, while abundant surface water with more rainfall on less permeable material made fluvial erosion active from early stages, the deficiency in surface water with less rainfall on more permeable material apparently attenuated fluvial erosion but possibly accentuated slope processes and slope failures by seepage water flow through more permeable material of low shear strength. The active erosion from early stages apparently resulted in the development of enduring similar low landforms later in the dynamic equilibrium stage. These experimental results indicate that similar landforms can emerge from different environmental and lithologic controls, and that process does not necessarily follow from form.     

Simulation analyses of buildings damaged in the 1995 Kobe,Japan, earthquake considering soil–structure interaction

A series of studies was conducted on three buildings of steel reinforced concrete structures with RC shear walls damaged in the 1995 Hyogo-ken Nanbu earthquake. These buildings are located in an area where structural damage centred around. Two of these buildings suffered severe damage, while the third was not structurally damaged. Our studies deal with site inspections, including micro-tremor measurement of buildings, the evaluation of input motions, and the response analyses considering soil–structure interaction. The results of simulation analyses of the two severely damaged buildings correspond to their actual damage state. From the response analyses of the one slender building with no structural damage, it was concluded that uplifting is the main reason it did not suffer any structural damage. Through these studies, the importance of soil–structure interaction and effective input motion is fully understood. Copyright © 1999 John Wiley & Sons, Ltd.     

Assessment of proposed approaches for bathymetry calculations using multispectral satellite images in shallow coastal/lake areas: a comparison of five models

Bathymetric information for shallow coastal/lake areas is essential for hydrological engineering applications such as sedimentary processes and coastal studies. Remotely sensed imagery is considered a time-effective, low-cost, and wide-coverage solution for bathymetric measurements. This study assesses the performance of three proposed empirical models for bathymetry calculations in three different areas: Alexandria port, Egypt, as an example of a low-turbidity deep water area with silt-sand bottom cover and a depth range of 10.5 m; the Lake Nubia entrance zone, Sudan, which is a highly turbid, unstable, clay bottom area with water depths to 6 m; and Shiraho, Ishigaki Island, Japan, a coral reef area with varied depths ranging up to 14 m. The proposed models are the ensemble regression tree-fitting algorithm using bagging (BAG), ensemble regression tree-fitting algorithm of least squares boosting (LSB), and support vector regression algorithm (SVR). Data from Landsat 8 and Spot 6 satellite images were used to assess the performance of the proposed models. The three models were used to obtain bathymetric maps using the reflectance of green, red, blue/red, and green/red band ratios. The results were compared with corresponding results yielded by two conventional empirical methods, the neural network (NN) and the Lyzenga generalised linear model (GLM). Compared with echosounder data, BAG, LSB, and SVR results demonstrate higher accuracy ranges from 0.04 to 0.35 m more than Lyzenga GLM. The BAG algorithm, producing the most accurate results, proved to be the preferable algorithm for bathymetry calculation.     

An analysis of the radar backscatter from oil-covered sea surfaces using moment method and Monte-Carlo simulation: preliminary results

An analysis of the radar backscattering from the ocean surface covered by oil spill is presented using a microwave scattering model and Monte-Carlo simulation. In the analysis, a one-dimensional rough sea surface is numerically generated with an ocean waveheight spectrum for a given wind velocity. A two-layered medium is then generated by adding a thin oil layer on the simulated rough sea surface. The electric fields backscattered from the sea surface with two-layered medium are computed with the method of moments (MoM), and the backscattering coefficients are statistically obtained with N independent samples for each oil-spilled surface using the Monte-Carlo technique for various conditions of surface roughness, oil-layer thickness, frequency, polarization and incidence angle. The numerical simulation results are compared with theoretical models for clean sea surfaces and SAR images of an oil-spilled sea surface caused by the Hebei (Hebei province, China) Spirit oil tanker in 2007. Further, conditions for better oil spill extraction are sought by the numerical simulation on the effects of wind speed and oil-layer thickness at different incidence angles on the backscattering coefficients.     

Atmospheric gravity waves identified by ground-based observations of the intensity and rotational temperature of OH airglow

Spectroscopic observations of OH airglow undertaken on May 2, 2006 at Uji, Japan reveal variations in intensity and rotational temperature related to the passage of an atmospheric gravity wave. The variations exhibit a period of approximately 1 h and magnitudes of 2–6% in intensity and 0.5–2% in rotational temperature. The vertical wavelength and intrinsic frequency of the atmospheric gravity wave were determined from the horizontal wavelength derived by an OH airglow imager, the background horizontal wind velocity obtained by the middle and upper atmosphere (MU) radar, and the dispersion relationship. The observed variations are consistent with the values calculated using the model of Liu, A.Z., Swenson, G.R. [2003. A modeling study of O₂ and OH airglow perturbations induced by atmospheric gravity waves. J. Geophys. Res. 108 (No. D4), 4151. doi:10.1029/2002JD002474].     

Numerical study of surface water circulation around Sekisei Lagoon, southwest Japan

This paper discusses the variability of surface currents around Sekisei Lagoon using a nested grid ocean circulation model. We developed a triple-nested grid system that consists of a coarse-resolution (1/60° or ∼1.85 km) model off Taiwan, an intermediate-resolution (1/300° or ∼370 m) model around the Yaeyama Islands, and a fine-resolution (1/900° or ∼123 m) model of Sekisei Lagoon. The nested grid system was forced by wind and heat flux calculated from six-hourly atmospheric reanalysis data and integrated over the period from May to July 2003. The coarse-resolution model was driven by lateral boundary conditions calculated from daily ocean reanalysis data to include realistic variation of the Kuroshio and mesoscale eddies with spatial scales of ∼500–700 km in the open ocean. The tidal forcing was included in the intermediate-resolution model by interpolating sea level data obtained from a data-assimilative tidal model. The results were then used to drive the fine-resolution model to simulate the surface water circulation around Sekisei lagoon. Model results show that (1) currents inside the lagoon are mainly driven by tide and wind; (2) there exists a strong southwestward current along the bottom slope in the southeast portion of the lagoon; the current is mainly driven by remote mesoscale eddies and at times intensified by the local wind; (3) the flow relaxation scheme is effective in reducing biases along the open boundaries. The simulated currents were used to examine the retention and dispersion of passive particles in the surface layer. Results show that the surface dispersion in the strong open ocean current region is significantly higher than that inside the lagoon.     

Partial breaching of Hattian Bala Landslide Dam formed in the 8th October 2005 Kashmir Earthquake, Pakistan

The 8th October 2005 Kashmir Earthquake of magnitude 7.6 triggered a huge landslide 3.5 km upstream of Hattian Bala town in the state of Azad Jammu Kashmir of Pakistan. The debris mass blocked two tributaries of the Karli branch of the Jhelum River and was breached on 9th February 2010. This debris dam provided us with a rare opportunity to keep careful and continuous eyes on its post-earthquake behavior especially as it was a serious threat to people living along the lower reaches of both the Karli and Jhelum Rivers. This paper describes post-formation behaviors of the debris mass, breaching-inflicted changes of not only the debris mass but also both upstream and downstream reaches based upon laser-scanned images of landforms and Differential Global Positioning System survey results.     

Geochemical Characteristics,Origin, and Evolution of Ore‐Forming Fluids of the Khut Copper Skarn Deposit,West of Yazd in Central Iran

The Khut copper skarn deposit is located at about 50 km northwest of Taft City in Yazd province in the middle part of the Urumieh‐Dokhtar magmatic arc. Intrusion of granitoid of Oligocene–Miocene age into carbonate rocks of the Triassic Nayband Formation led to the formation of marble and a calcic skarn. The marble contains high grade Cu mineralization that occurs mainly as open space filling and replacement. Cu‐rich sulfide samples from the mineralized marble are also anomalous in Au, Zn, and Pb. In contrast, the calcic skarn is only weakly anomalous in Cu and W. The calcic skarn is divided into garnet skarn and garnet–pyroxene skarn zones. Paragenetic relationships and microthermometric data from fluid inclusions in garnet and calcite indicate that the compositional evolution of skarn minerals occurred in three main stages as follows. (i) The early prograde stage, which is characterized by Mg‐rich hedenbergite (Hd_53.7Di_42.3–Hd_86.1Di_9.5) with Al‐bearing andradite (69.8–99.5 mol% andradite). The temperature in the early prograde skarn varies from 400 to 500°C at 500 bar. (ii) The late prograde stage is manifested by almost pure andradite (96.2–98.4 mol% andradite). Based on the fluid inclusion data from garnet, fluid temperature and salinity in this stage is estimated to vary from 267 to 361°C and from 10.1 to 21.1 wt% NaCl equivalent, respectively. Pyrrhotite precipitation started during this stage. (iii) The retrograde stage occurs in an exoskarn, which consists of an assemblage of ferro‐actinolite, quartz, calcite, epidote, chlorite, sphalerite, pyrite, and chalcopyrite that partially replaces earlier mineral assemblages under hydrostatic conditions during fracturing of the early skarn. Fluids in calcite yielded lower temperatures (T < 260°C) and fluid salinity declined to ～8 wt% NaCl equivalent. The last stage mineralization in the deposit is supergene weathering/alteration represented by the formation of iron hydroxide, Cu‐carbonate, clay minerals, and calcite. Sulfur isotope data of chalcopyrite (δ³⁴S of +1.4 to +5.2‰) show an igneous sulfur source. Mineralogy and mineral compositions of the prograde assemblage of the Khut skarn are consistent with deposition under intermediately oxidized and slightly lower fS₂ conditions at shallow crustal levels compared with those of other typical Fe‐bearing Cu–Au skarn systems.     

The b value spectrum and η value by the moment method

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