In 1989, the International Commission on Stratigraphy established a Working Group on the Terminal Proterozoic Period. Nine years of intensive, multidisciplinary research by scientists from some two dozen countries have markedly improved the framework for the correlation and calibration of latest Proterozoic events. Three principal phenomena--the Marinoan ice age, Ediacaran animal diversificatio...

Circular graphite discs, among abundant irregular graphite particles, have been extracted from ArcheanPaleoproterozoic amphibolite grade metamorphic rocks in the Wutaishan area of North China. Raman spectroscopic analysis indicates that these graphite discs experienced maximum metamorphic temperature of 513 ± 50 °C. The discs bear morphological features related to metamorphism, but they are als...

The appearance of photosynthetic eukaryotes (algae and plants) dramatically altered the Earth's ecosystem, making possible all vertebrate life on land, including humans. Dating algal origin is, however, frustrated by a meager fossil record. We generated a plastid multi-gene phylogeny with Bayesian inference and then used maximum likelihood molecular clock methods to estimate algal divergence ti...

For the first time, an assemblage of cryptospores, which includes 10 species belonging to nine genera, from the Upper Ordovicianstrata, is being reported, in Iran. These cryptospore assemblages were recovered from the upper part of Ghelli Formation., from theeastern Alborz Mountain range. These peri-Gondwanan cryptospores have been classified based on their morphology (monad, truedyad, pseudody...

Coupled dual-beam focused ion beam electron microscopy (FIB-EM) has gained popularity across multiple disciplines over the past decade. Widely utilized as a stand-alone instrument for micromachining and metal or insulator deposition in numerous industries, the submicron-scale ion milling and cutting capabilities of FIB-EM systems have been well documented in the materials science literature. Th...

Abstract The Anti-Atlas contains a thick, volcanic-free Ordovician succession that originally deposited in passive-margin basin. Three main sedimentary packages are bounded by major unconformities: (i) the Tremadocian–Floian Lower Fezouata and Upper formations, which unconformably overlie palaeorelief of Cambrian rifting volcanosedimentary complexes, subsequently topped Dapingian paraconformabl...