The highly deformed Zhob ophiolite comprises the Ali Khanzai, Naweoba, and Omzha blocks. Each of these blocks contains both felsic and mafic dyke swarms. The felsic dykes occur as patches and pods in gabbroic bodies of crustal sections while mafic dykes crosscut the mantle peridotite of these blocks. Felsic dykes are plagiogranite and are composed of quartz, plagioclase and accessory ferromagnesian minerals whereas mafic dykes are basaltic in composition and contain largely plagioclase, clinopyroxene, and hornblende with minor quartz grains. Major, trace and rare earth elements have been analyzed in the felsic and mafic to assess the tectonomagmatic setting of the Zhob ophiolite. The felsic dykes are calc-alkaline oceanic plagiogranites while mafic dykes are tholeiitic in composition. Chondrite normalized patterns for the felsic dykes are characterized by low values of the REEs and positive Eu anomalies which indicate that they were formed by partial melting of basic rocks under hydrous conditions. The mafic dykes show very slight Nb depletion and enrichment in large ion lithophile elements (LILE) over high field strength elements (HFSE) which suggest that mafic dyke swarms are derived from an undepleted mantle source. Oceanic rocks with such characteristics are generally thought to have formed by processes involving a subduction zone component in the source region by fluids released from the subducting slab. These features suggest a subduction related setting which indicates an island arc, back arc or supra-subduction zone affinity for the formation of both felsic and mafic dykes of the Zhob ophiolite.
The Qobadlu intrusive body in the northern part of the Sanandaj-Sirjan Zone (SaSZ) has been recognized as a remnant of Cretaceous magmatic activity in the NW Iran. The Qobadlu gabbroic body has a calc-alkaline affinity. Based on the zircon dating (U-Pb), the coarse grained Qobadlu gabbro were crystallized at 99 Ma. The Low SiO2 and high Mg # Cr and Ni contents of the Qobadlu rocks can be indicate the upper mantle source for parental magma. Positive anomalies of the LILE and LREE, coupled with negative anomalies of Nb and Ti, and high ratios of La/Nb (1.3-3.3) and Ba/Nb (20-90) can be indicate that the samples are sourced from an amphibole enriched spinel lherzolitic mantle and developed through Neo-Tethyan subduction regime. Variations in incompatible elements suggest the crustal assimilation and fractionation crystallization during magma ascent. Considering the Cretaceous magmatic activity of the calcalkaline, these rocks have seemingly formed in the extensional basin related to the Neotethys subduction.
Accurately estimating the construction duration of long tunnels during the feasibility and initiation phases is crucial. Traditional estimation methods often lack precision. This paper introduces novel simulation-based approaches to provide more accurate forecasts of tunnel construction time, thereby minimizing the gap between planned and actual durations. This innovation involves identifying risks influencing tunnel construction, categorized as known and unknown, by experts. These risks are then ranked and weighted using the Fuzzy Analytic Hierarchy Process (FAHP). Significant risks are simulated as inputs in MATLAB software using the Monte Carlo method. The results indicate a six-year construction duration for the identified risks. The probability of adhering to the schedule is 100% in the first year, decreasing to 89% in the second year, 92% in the third year, and 90% in the fourth, fifth, and sixth years. For unknown risks, the probability is 90% in the first year, 93% in the second year, 90% in the fourth year, and 92% in the fifth and sixth years. Based on these findings, contingency and management reserves should be added to the forecasted schedule in accordance with the PMBOK standard to minimize discrepancies between planned and actual schedules.
This paper discusses shortening and strain in folds, highlighting the structural variation in the southern Kerman coal field. In this tectonically active region, the stress resulting from compression and tension in central Iran has largely manifested as folding and faulting, which constitute the major deformation of the area. The research results show compression of the folds in the study area. The results also indicate the complete reversal of the relative ages of ductile and brittle structures, due to faulting that sheared the limbs of most folds in the region. As can be inferred, except for the Kuhbanan and Lekarkoh faults, which existed before the folds and hence played a major role in the area's formation, the remaining faults in the region formed after the folds. In this aspect, the maximum shortening percentage in the area is 70% for the Babnizo fold, and the minimum is 42% for the Eshkli syncline.
The Mekong Delta is the third-largest delta in the world, with a large population, a significant food production area in Vietnam and home to large-scale biodiversity, is seriously affected by erosion-accretion of the coast, land subsidence. Several dams have been built upstream of the delta (Manwan, Nuozhadu...), and large-scale commercial sand mining in the river and delta channels, along with subsidence caused by groundwater extraction, are the causes of sediment decline in the Mekong Delta. This affects the daily lives of more than 21 million people. Using high-resolution satellite imagery (Landsat) for the period 1989-2020, this paper assesses erosion-accretion rates at the Mekong estuary to Ca Mau cape. Extracting the shoreline using the Normalized Difference Vegetation Index used to measure vegetation change and the Digital Shoreline Analysis System used to analyze changes in the shoreline. The results show that the Mekong estuary is having an alternating process of erosion-accretion, the balance of erosion-accretion tends to imbalance with dominant accretion. The Mekong estuary area, including the Tieu, Dai, Ba Lai, Ham Luong, Co Chien, Cung Hau, Dinh An and Tran De mouths, experiences erosion and accretion ranging from 1.37 to 120.98 m/yr and 74.94 to 117.06 m/yr, respectively. From My Thanh mouth to Ca Mau Cape, with erosion ranging from 66.07 to 115.5 m/yr and accretion from 29.67 to 91.06 m/yr, respectively. Our research emphasizes the fragility of the Mekong Delta coastline and underscores the critical role of remote sensing imagery in effective shoreline management.
