-A complete conversion series for mica/smectites was found in a hydrothermal alteration envelope around Kuroko-type ore deposits at the Shinzan area, Akita Prefecture, Northeast Japan. The minerals are an alteration product of volcanic glass of Miocene age and are commonly associated with zeolites and silica minerals. Degrees of ordering of interstratification of the minerals change discontinuo...

tourmalinization characterizes the most pervasive alteration type in the nezam abad ore deposit, west-central iran. it delineates high-temperature centers of mineralization and together with quartz and cassiterite form inner parts of the alteration halo. the composition of tourmalines plots mostly along and between the proton and alkali-deficient end members. tourmaline in quartzdioritic host i...

[1] Recent spectroscopic detections of CH4 in the atmosphere of Mars are the first definitive observations of an organic compound on that planet. The relatively short photochemical lifetime of CH4 ( 300 years) argues for a geologically young source. We demonstrate here that lowtemperature alteration of basaltic crust by carbon-bearing hydrothermal fluid can produce the required CH4 flux of 1 10...

Hydrothermal systems have previously been reported in ancient Noachian and Hesperian-aged craters on Mars using CRISM but not in Amazonian-aged impact craters. However, the nakhlite meteorites do provide evidence of Amazonian hydrothermal activity. This study uses CRISM data of 144 impact craters of ≥7 km diameter and 14 smaller craters (3–7 km diameter) within terrain mapped as Amazonian to se...

The Sungun porphyry copper deposit is located in northwestern Iran and is associated with diorite/granodiorite to quartz-monzonite of Miocene age, which intruded Eocene volcanosedimentary and Cretaceous carbonate rocks. Copper mineralization was accompanied by both potassic and phyllic alteration. Three main mineralization related alteration episodes (potassic, transition, and phyllic alteratio...

Introduction: Geomorphological observations of Mars surface and mineral detection, in particular hydrated sulphates, militate for the idea that liquid water have existed on Mars surface, even if physical conditions forbid its presence today. Beside the sul-phate formation which requires particular chemical conditions, clay minerals are of particular interest because they are the first by-produc...