Formation mechanism of the moniliform seamounts outside the West Melanesian Trench

Our study on the seamounts in the southeast Caroline Plate reveals a formation of a special kind of seamounts in the oceanic basin. These moniliform seamounts link up like the reason of hotspots, but the tectonic factors lead to their formation. The differential motions of the Caroline, North Bismarck, and Pacific plates resulted in the shear stress field by the West Melanesian Trench. The R and R′ faults can be distinguished obviously by seafloor topography. The evolution history of these seamounts can be subdivided into two stages as follows. (a) The R′ faults developed firstly as normal faults to generate ridges on these faults as the release of the underlying sediments. (b) The R faults appeared as shear faults and cut off the ridge from the older R′ faults. These faults can be very deep fractures, which cut through the lithosphere and produced a NW‐trending negative anomaly in isostatic gravity anomaly. As the pressure is released by the R faults, the sediments releasing under the R faults accumulated into these seamounts. The other sections of the R faults performed like a valley because of the leakage of sediments along the faults. Sediments would also release along the R faults to generate ridges when no seamount occurs on the faults.

Gold‐copper deposits in Wushitala, Southern Tianshan, Northwest China: Application of ASTER data for mineral exploration

The Southern Tianshan area is one of the most important gold belts identified by many world‐class, super large and large gold deposits such as Muruntau (Uzbekistan), Kumtor (Kyrgyzstan), and Jilau (Tajikistan). Some medium‐ to small‐scale gold deposits, such as Sawayaerdun and Bulong, have been discovered and reported in recent years at the China part of the belt. The study area, named the Wushitala area, is located in the eastern part of Southern Tianshan, and it has a strong potential for gold and other metallic mineral deposits. This study utilizes various image processing techniques, including false colour composite, band ratios, and matched filtering, to process Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) data and map the distribution of hydrothermal minerals (e.g., muscovite, kaolinite, chlorite, epidote, goethite, and malachite) related to the known deposits in the Wushitala area. The identified alteration zones are coincident with the known gold and copper deposits and field samples from the study area. The distribution of the alteration zones also indicates that the acid intrusions and regional structures play an important role in focusing the mineralizing fluids. The results show that ASTER data accompanied with image processing methods and reference spectra (e.g., JPL, lab, or field measured) could be an effective technique for mapping hydrothermal alteration zones in areas with no dominant vegetation cover. Due to the extensively distributed acid intrusions and structures along the Southern Tianshan Belt, the mineral prospecting methodology is suggested for application in similar geological settings in the belt.

New study details earthquake, flood risk for Eastern European, Central Asian countries

By Madeleine Jepsen How will future disasters affect countries in Eastern Europe and Central Asia? Researchers aiming to answer this question used projected changes in population and Gross Domestic Product (GDP) for 33 countries, along with climate, flood and earthquake risk models, to estimate how each country is affected by flooding and earthquakes now and in the future. In addition, the earthquake model was used to estimate fatalities and capital …