Shallow, near-surface magma emplacement into a porous, unlithified sandstone occurred by forceful dike dilation and was accompanied by a localized hydrothermal event. Petrographic fabric, authigenic mineralogy and petrophysical data, grade smoothly through the quartzite contact zone outward into the friable Inmar sandstone of Makhtesh Ramon, Israel. Quartz grain deformation, fracturing and rehealing of grains, and pressure solution constitute overwhelming evidence of a compressive environment adjacent to dike margins, albeit with temperatures and pressures insufficient to fully recrystallize detrital grains. Dikes were accommodated primarily by the repacking of the sandstone with both brittle and elastic grain interaction. Post emplacement heating together with elastic compressive stress dissipation, lead to fracture healing and pressure solution. The occasional columnar-jointing must be related to thermal contraction of the quartzite during later cooling and resulting mode I cracks. The alteration of both contact zone and dike material occurred via a transitory and confined hydrothermal seepage up dike margins. Elsewhere around the world highly altered intrusions bordered by indurated sometimes uniformly jointed sediments, may also be the result of forceful magma emplacement and hydrothermal alteration at near-surface levels.

First paleomagnetic and isotope-geochronological data on four basaltic volcanic pipes of the North-Minusinsk depression are reported. It is shown that the volcanic pipes appeared between 82 and 77 Ma ago. All ChRM directions of the pipe basanites are of reverse polarity. This fact is in agreement with the 40Ar-?9Ar ages of the rocks (within the accuracy of the 40Ar-39Ar method). The revealed ChRM corresponds to the end of chron 33R of reverse polarity (according to the geomagnetic-polarity time scale). The paleomagnetic poles of the studied pipes differ from the APWP of Eurasia.

In the North-Minusinsk intermontane depression, volcanic

Книга представляет собой первое сводное монографическое описание палеозойского интрузивного магматизма Урала. Изложены результаты авторских разработок, на основании которых сформулированы особенности ультрамафит-мафитовых, габбро-гранитоидных и гранитных комплексов, позволяющие понять природу и закономерности эволюции орогена и его эндогенной активности в палеозое. Рассмотрены типовые объекты, на которых, по существу, зарождались российская петрология и геохимия. Для них получены новые данные по геологии, петрологии, геохимии и изотопии с использованием самых совершенных на сегодняшний день методик. Приведены параметры главного для Урала надсубдукционного островодужного и окраинно-континентального, а также обдукционного и коллизионного магматизма. Подробно освещены проблемы и результаты изотопного датирования магматических комплексов, рассмотрена их корреляция.

Книга предназначена для геологов, петрологов и геохимиков.