Anomalies of Thermomagnetic Characteristics of Lower Cretaceous Red-Beds in the Tadjik Depression (Southern Tien-Shan)

The paper features data on thermomagnetic characteristics of the red-bed sediments of the Lower Cretaceous of the Tadjik depression which turned out to be somewhat anomalous. The thermomagnetic characteristics of monolithic samples are stable under long-term heating (2–3 hours) at high temperature (600°–700°C). At the same time, the thermomagnetic characteristics of the powders, obtained from heated monolithic samples, display instability under even lesser temperatures. During heating at 600°–700°C, part of the hematite, dispersed in the rock, turns into stable maghemite. Disintegration of the monoliths changes the properties of the secondary maghemite - it becomes unstable to heating and at temperatures of 550°-600°C irreversibly changes into hematite.