in order to investigate deformation history preserved in the calcite twins in the hinterland of zagros, several samples have been collected from calcschists of the paleozoic sargaz complex in the faryab area, se iran. these samples are related to f1-recumbent folding and thrust shear zones. the twin width is about 1 and 3.8 µm (thin-twin regime); the twin strain amounts 5 and 10%; twin intensit...

T h e Permo-Carboniferous sedimentary facies development in Thai land reflects the late V a r i s c a n orogeny in S E A s i a . During the Carboniferous and Permian, a N S trending trough separated the " S h a n T h a i C r a t o n " and the " Indosinia C r a t o n " . In this pelagic basin, deposition of ribbon cherts continued from pre-Asselian to Kubergandian. I n L o w e r Permian, carbona...

Abundant graphite particles occur in amphibolite-grade quartzite of the Archean-Paleoproterozoic Wutai Metamorphic Complex in the Wutaishan area of North China. Petrographic thin section observations suggest that the graphite particles occur within and between quartzite clasts and are heterogeneous in origin. Using HF maceration techniques, the Wutai graphite particles were extracted for furthe...

The identification and confirmation of bona fide Archean-Paleoproterozoic microfossils can prove to be a challenging task, further compounded by diagenetic and metamorphic histories. While structures of likely biological origin are not uncommon in Precambrian rocks, the search for early fossil life has been disproportionately focused on lesser thermally altered rocks, typically greenschist or l...

Orogenic gold de pos its are char ac ter ized by struc tur ally con trolled, low-sul phide quartz veins that formed prox i mal to deep-crustal faults in greenschist-fa cies meta mor phic ter ranes. These de pos its, pre vi ously re ferred to as mesothermal, greenstone-hosted, shear-hosted and turbidite-hosted de pos its, have a wide range of as so ci ated min er al iza tion styles and as so ci ...

The metamorphic sole rocks at the base of mantle peridotites from the Mersin ophiolite consist of amphibolites and metasedimentary lithologies. Mineral parageneses in the metamorphic sole rocks exhibit amphibolite and greenschist facies assemblages. Geothermobarometric studies based on mineral assemblages and chemical compositions of minerals indicate that average metamorphic temperature during...

The western Tianshan high-pressure/low-temperature orogenic belt in NW China contains eclogite-facies metavolcanic rocks and omphacite-bearing blueschists. Previous Sm-Nd (omphacite, garnet, glaucophane, whole rock) and Ar/Ar (crossite) dating of eclogite-facies rocks has suggested an age of ca. 345 Ma as the best approximation for the timing of peak metamorphic conditions. The samples describe...

Ancient geological materials are likely to be contaminated through geological times. Thus, establishing the syngeneity of the organic matter embedded in a mineral matrix is a crucial step in the study of very ancient rocks. This is particularly the case for Archean siliceous sedimentary rocks (cherts), which record the earliest traces of life. We used electron paramagnetic resonance (EPR) for a...