巴基斯坦山达克矿区ASTER遥感数据蚀变信息提取及找矿预测

巴基斯坦查盖火山岩浆岩带属于特提斯成矿域的重要组成部分之一,是巴基斯坦境内最重要的斑岩型铜矿带,但目前其相关的遥感研究还较少,制约了对该成矿带的找矿潜力分析。本文以山达克矿床及其周边为研究区,对先进星载热辐射与反射辐射计(Advanced Spaceborne Thermal Emission and Reflection Radiometer, ASTER)数据进行RBD (Relative absorption band depth)比值假彩色合成、主成分分析、光谱角制图等处理,获得蚀变遥感异常信息分布特征,通过对蚀变特征和主要控矿要素进行遥感研究,建立了山达克矿床遥感找矿模型并开展成矿预测,为该成矿带矿产勘查提供借鉴。根据建立的遥感找矿模型,圈定了找矿预测靶区10处。对矿区东矿体和矿区北部的2个靶区进行野外验证,证实了提取结果与实际地质事实吻合较好,对矿区岩石样品进行光谱实测,表明样品实测光谱曲线与标准矿物光谱曲线的吸收特征位置高度相似,证实了研究区绢云母化、青磐岩化等蚀变较强且分布较广。结果表明本次研究提取的矿化蚀变结果可信度较高,可为后续找矿勘查工作提供参考。     

The impact of land use and land cover changes on soil erosion in western Iran

Natural Hazards - Analysis of long-term land use and land cover (LULC) changes requires up-to-date remotely sensed data to assess their effects on erosion. This is a particularly important...     

Ionization State in PDR (IC 63 nebula)

We investigated the chemical evolution in IC 63 nebula, a photo-dominated region (PDR). The chemical structure and the ionization state depend directly on the intensity of the incident UV radiation. The electron density is also affected by the incident UV radiation. It decreases gradually with the increase of the depth in the cloud varying from 5.9×10^-5 at the surface to 9.6×10^-9 in the core. Ionic carbon(C⁺) dominates the electron density in the outer region while ionic metals and other ions (H⁺, CH₂D⁺, and HCO⁺) are the most dominant in the deepest region. Our results at A _V = 6.7 mag are in good agreement with observations except in the case of H₂S, where the calculated value is lower than the observed value by about two orders of magnitude.     

Possibility of the Application of Danube,Sava and Morava River Area Shallow Aquifer Groundwater (Serbia) in the Irrigation Purposes

Water Resources - This paper presents the results of the groundwater quality assessment, on the Serbian Danube, Sava and Morava River water area, for irrigation purposes. The analysis was done at...     

Vorticity analysis in the Zagros orogen,Shiraz area,Iran

International Journal of Earth Sciences - Quantitative vorticity analyses in orogenic belts are essential for studying the kinematics of deformation and can be performed using a range of methods....     

3D Gravity Inversion of Northern Sinai Peninsula: A Case Study

The Sinai Peninsula has attracted the attention of many geological and geophysical studies as it is influenced and bounded by major tectonic events. Those are (1) the Mesozoic to Early Cenozoic tectonically active opening of the Tethys, (2) the Late Cretaceous to Early Tertiary (Laramide) Syrian arc system, due to closing of the Tethys (3) the Oligo-Miocene Gulf of Suez rifted basin, and (4) the Late Miocene to Recent transform Dead Sea–Gulf of Aqaba rift. Additionally, the shear zones inside Sinai such as the Ragabet El-Naam and Minsherah-Abu Kandu Shear Zones. Each of these major tectonic events has affected dramatically the structure evolution of the northern Sinai area. The present paper estimates the 3D density contrast model using the gravity data of northern Sinai. The estimated 3D density contrast model elucidated the peculiarities of the main structural elements in the region. The estimated 3D density contrast model showed the high and low gravity anomalies that form the main mountains and main valleys in northern Sinai. The estimated low density zones are in agreement with the inferred faults resulting from the first horizontal derivative. Comparing the 3D model with the tectonic history of the region and the results of the first horizontal derivative and least square separation increased the reliability of the model.     

Offshore sand sources for beach replenishment: Potential borrows on the continental shelf of the Eastern Gulf of Mexico

Erosion of sandy beaches is a worldwide problem that elicits innovative geoengineer‐ing techniques to reduce adverse impacts of shoreline retreat. Beach replenishment has emerged as the “soft”; shore‐stabilization technique of choice for mitigating beach erosion. This method of shore protection involves the addition of sand to the littoral sediment budget for sacrificial purposes. Because inland sand sources are often uneconomical or impractical to use, and known nearshore sources are limited, finding adequate quantities of suitable sand on the inner continental shelf is often vital to beach replenishment projects. The technical studies of survey and materials analysis that identify and delineate usable sand sources are sometimes almost as expensive as small‐project dredging, pumping, and placing the sand on the beach as fill. Inadequate quantity or substandard quality of shelf sand, as well as often‐prohibitive overhead expenses, thus compel shoreline managers to seek suitable sand sources offshore.

In the study area off the central‐west coast of Florida, offshore potential borrow areas (PBAs) were identified on the basis of studies conducted in reconnoitory and detailed phases. Sophisticated state‐of‐the‐art equipment used in this investigation provided more detailed subbottom mapping information than is normally obtained with conventional seismic equipment. An example of sand exploration studies was incorporated in a 215‐km² survey of offshore areas by conducting bathymetric surveys and subbottom seismic profiling, collecting jet probes, grab samples, and vibrocores, and analyzing sediment grading in subsamples from vibrocores. These combined analyses indicated that at least 8.8 ×10⁶ m³ of sand is available in potential borrow areas from 7.0 to 12 km offshore in water depths of 8.0 to 11.5 m. In the PBAs, mean grain size of sand falls into the range 0.13–0.53 mm, sorting averages 0.65–1.31ø, and the overall silt content varies from 3.9–8.5%. High silt contents (13–19%) mapped in some areas make these sedimentary deposits unsuitable as fill for artificial beach renourishment.