Integrating remote sensing and geophysical data for mapping potential gold mineralization localities at Abu Marawat area, central Eastern Desert, Egypt.

Abu Marawat area in the Central Eastern Desert of Egypt is a very promising mineralization district located in the Golden Triangle area. The current study provides an integrated approach from multisource datasets including; remote sensing, airborne geophysical spectrometry and magnetic data supported by field studies and spectroscopic analyses for delineating potential mineralization localities. Several remote sensing techniques were adopted including; Band Ratios, Relative Band Depth, Mineralogical Indices, Spectral Angle Mapper, and Constrained Energy Minimization. These techniques showed that the alteration mineral assemblage is mainly, kaolinite, sericite, and iron oxides, with less abundant chlorite, epidote, and carbonates. In addition, the radiometry data were processed to map the localities with the highest possibility of potassic alteration abundance by integrating the potassium distribution, K/eTh ratio, and the F-parameter maps. The surface and subsurface linear structural features were also mapped using Digital Elevation Model (DEM) and aeromagnetic data, respectively. The surface linear structures were found exhibiting E-W and NE-SW trends, while, the subsurface structures showed dominant NW-SE trend. All the depicted fault trends match well with the local and regional geological and tectonic setting of the study area suggesting structural control on the mineralization in this area. Integration between the results obtained from both the remote sensing and the geophysical data was conducted by a GIS weighted overlay model. The obtained mineralization potentiality map highlights eight potential localities for mineralization. The accuracy of the adopted methodology was demonstrated through fieldwork and spectral analyses; several alteration indicators were observed, including quartz veins, iron oxides, kaolinite, malachite, montmorillonite, chlorite, talc, and sericite alteration indicator minerals. The adopted remote sensing-geophysical approach showed being very effective for mapping the hydrothermal gold-related alteration zones, and is recommended for other similar investigations.

Drainage vs. non-drainage after cholecystectomy for acute cholecystitis: a retrospective study.

Many surgeons practice prophylactic drainage after cholecystectomy without reliable evidence. This study was conducted to answer the question whether to drain or not to drain after cholecystectomy for acute calculous cholecystitis. A retrospective review of all patients who had cholecystectomy for acute cholecystitis in Aseer Central Hospital, Abha, Saudi Arabia, was conducted from April 2010 to April 2012. Data were extracted from hospital case files. Preoperative data included clinical presentation, routine investigations and liver function tests. Operative data included excessive adhesions, bleeding, bile leak, and drain insertion. Complicated cases such as pericholecystic collections, mucocele and empyema were also reported. Patients who needed therapeutic drainage were excluded. Postoperative data included hospital stay, volume of drained fluid, time of drain removal, and drain site problems. The study included 103 patients allocated into two groups; group A (n  =  38) for patients with operative drain insertion and group B (n  =  65) for patients without drain insertion. The number of patients with preoperative diagnosis of acute non-complicated cholecystitis was significantly greater in group B (80%) than group A (36.8%) (P < 0.001). Operative time was significantly longer in group A. All patients who were converted from laparoscopic to open cholecystectomy were in group A. Multivariate analysis revealed that hospital stay was significantly (P < 0.001) longer in patients with preoperative complications. There was no added benefit for prophylactic drain insertion after cholecystectomy for acute calculous cholecystitis in non-complicated or in complicated cases.