Evidence in Archaean Alkali Feldspar Megacrysts for High-Temperature Interaction with Mantle Fluids

Microstructures in Two Alkali Feldspar Megacrysts from the Papuk Mt., Croatia

The Papuk Mt. belongs to the Slavonian Mountains in Croatia. It is situated in the southernmost part of the Tisza Megaunit (Fig. 1). Comprehensive reviews of the geological setting of this area are given by JAMIČIĆ & BRKIĆ (1987), JAMIČIĆ (1989) and KOROLIJA & JAMIČIĆ (1989). VRAGOVIĆ (1965) gave a detailed petrographic description of the gneisses, granitoids and the pegmatites of this region. ...

Improving Thermal Stability of Starch in Formate Fluids for Drilling High Temperature Shales

Starch is one of the most widely used biopolymers in water based drilling fluids to control fluid loss. The thermal stability of starch in common drilling fluids is low (93 °C). In this study, the thermal stability of starch has been evaluated in sodium/potassium formate and potassium chloride fluids. Samples of mud were prepared by formate salts (sodium and potassium) and potassium chloride wi...

Cathodoluminescence Characterization of Maskelynite and Alkali Feldspar in Shergottite

IN SHERGOTTITE. M. Kayama, T. Nakazato, H. Nishido, K. Ninagawa and A. Gucsik Research Institute of Natural Sciences, Okayama University of Science 1-1 Ridai-cho, Okayama, 700-0005, Japan ([email protected]), Department of Applied Physics, Okayama University of Science 1-1 Ridai-cho, Okayama, 700-005, Japan, Max Planck Institute for Chemistry, Department of Geochemistry, Joh.-J. Becherweg 27...

Late-stage Fluids on the Ll Chondrite Parent Body: Evidence from Feldspar in the Ll4 Chondrites

Fossil evidence of Archaean life.

Evidence for the existence of life during the Archaean segment of Earth history (more than 2500 Myr ago) is summarized. Data are presented for 48 Archaean deposits reported to contain biogenic stromatolites, for 14 such units reported to contain 40 morphotypes of putative microfossils, and for 13 especially ancient, 3200-3500 Myr old geologic units for which available organic geochemical data a...