Relationship between Landslides, Geologic Structures, and Hydrothermal Alteration Zones in the Ohekisawa-Shikerebembetsugawa Landslide Area, Hokkaido, Japan

This paper elucidates the relationship between landslides, geologic structures, and hydrothermal alteration zones based primarily on X-ray powder diffraction and uniaxial compressive strength tests on weakly weathered and hydrothermally altered rocks from the Ohekisawa-Shikerebembetsugawa landslide area in Teshikaga Town, Hokkaido, Japan. The OHS （Ohekisawa slide） occurred on a dip slope of sedimentary rocks from the Upper Miocene Shikerepe Formation within a homocline, and also on weathered and hydrothermally altered rocks within the boundary area between the hydrothermal smectite zone and smectite-bearing mordenite zone. The SHS （Shikerebembetsugawa slide） occurred on a dip slope of sedimentary rocks from the Upper Miocene Hanakushibe Formation within wavy folds and was also controlled by a cap rock of Teshikaga Volcano Somma Lava. The SHS occurred also on weathered and hydrothermally altered rocks within the boundary area between the hydrothermal smectite zone and smectite-bearing laumontite zone. The mechanical properties of smectite, smectite-bearing mordenite, and smectite-bearing laumontite zone weakly weathered rocks indicate that they are very weak, soft rocks. These landslides are regarded as HAZLs （hydrothermal alteration zone landslides）. The hydrothermal alteration yielding smectite is thus closely related to these two ancient landslides, suggesting that the potential for HAZLs within a hydrothermal area can be assessed based on the swelling clay mineral-beating hydrothermal alteration types, dip slope, and cap rock.

Oxygen Isotope Characteristics of the Footwall Alteration Zones in the Hongtoushan Volcanogenic Massive Sulfide Deposit,Liaoning Province,China and Restoration of Their Formation Temperatures

The Hongtoushan Volcanogenic Massive Sulphide Deposit（VMSD）occurs in the Hunbei granite-greenstone terrane,Liaoning Province,NE China.Rocks in the mining area have been metamorphosed around 3.0-2.8 Ga to upper amphibolite facies at temperatures between 600℃and 650℃.Cordierite-anthophyllite gneiss（CAG）in the Hongtoushan mining area,which occurs hundreds of meters below the ore horizon,corresponds to the metamorphosed semi-conformable alteration zone of the VMSD hydrothermal system,whereas the one immediately below the main ore layer represents the metamorphosed pipe-like alteration zone.Whole-rock oxygen isotope signatures were well preserved in both types of CAGs,although the mineral components have been entirely changed during regional metamorphism.Therefore,whole-rock oxygen isotopes can be used to estimate the formation temperature of both types of alteration zone.Calculations show that the semi-conformable and pipelike alteration zones for the Hongtoushan submarine hydrothermal system were formed at 290-360℃and 285-320°C,respectively,whereas estimates for the former were slightly higher than that of the latter,indicating that the semi-conformable alteration zone represents the deep part of the Hongtoushan seafloor hydrothermal system,while the pipe-like alteration zone represents the discharge conduits for metal-rich fluids,which is closer to the seafloor.

Metallogenic Processes:Evidencesfrom Zoning Patterns of Mineralization and alteration and fluid inclusion geochemistryin the Lehong Zn-Pb Deposit in Northeastern Yunnan, China

1 Introduction The large clusters of Zn-Pb deposits in northeastern Yunnan,located in the southwestern margin of the Yangtze Block,are an important part of the Sichuan-YunnanGuizhou Pb-Zn Poly-metallic Metallogenic Triangle Area

Integrated Structure and Mineralization Study Using Aero-Magnetic, Aero-Spectrometric and Remote Sensing Data at Esh El-Mallaha Area, Eastern Desert, Egypt

The main scope of this research is to detect geologic structure trends affecting the study area, determine uranium anomalous areas and define alteration zones. Airborne magnetic data were used to detect the geologic structure trends affecting the study area through applying edge detectors such as total horizontal derivative, analytic signal and tilt derivative. The radio-spectrometry data and Landsat image data were used in determining the uranium anomalous areas and alteration zones. The integration between geology, magnetic and Landsat image was applied through constructing lineaments density map for the three data sets resulting in the leading of NW-SE trend all over the area. This integration makes clear that the basement (Red Sea hills), Esh El-mallaha range and G. Zeit are limiting two large basins (West Mallaha and Zeit). In addition, the main areas of uranium enrichment (Duwi formation at Esh El-Mallaha range) are found to be well related to alteration zones.