Silica is crucial to terrestrial plant life and geochemical cycling on Earth. It also implicated in the evolution of mammalian teeth, but there debate over which type siliceous particle has exerted strongest selective pressure tooth morphology. Debate revolves around amorphous silica bodies (phytoliths) present plants various forms grit—that is, crystalline quartz (sand, soil, dust)—on surfaces...

High-pressure (0.8 gigapascals) granulite facies garnet from Gore Mountain, New York, hosts multiple solid inclusions containing the low-pressure silica polymorph cristobalite along with albite and minor ilmenite. Identification of cristobalite is based on Raman spectra, electron microprobe analysis, and microthermometric measurements on the alpha/beta phase transformation. The cristobalite plu...

Sponge remains have been identified in the Early Vendian Doushantuo phosphate deposit in central Guizhou (South China), which has an age of approximately 580 million years ago. Their skeletons consist of siliceous, monaxonal spicules. All are referred to as the Porifera, class Demospongiae. Preserved soft tissues include the epidermis, porocytes, amoebocytes, sclerocytes, and spongocoel. Among ...

The Longtan Formation of the Upper Permian in Sichuan Basin has become a significant target for shale gas exploration recent years. Multiple methods, including outcrop observations, thin sections, total organic matter content, X-ray diffraction and scanning electron microscopy were used to investigate mineralogy, lithofacies assemblages their relationships with deposition environment. mineral c...

Abstract Ecological status classification systems based on biological elements (e.g., macroinvertebrate communities) are dependent their response to different pressures. However, there is a need determine if invasive species should be incorporated indicator parameters (i.e. metrics measurements of richness and diversity) or as pressure affecting such parameters. Moreover, because ecosystem lack...

Examination of surficial sediments at 16 stations shows minor, but consistent differences in the numbers and kinds of siliceous microfossils deposited in different regions of Lake Baikal. There is a general north-south decreasing trend in total microfossil abundance on a weight basis. Endemic plankton diatom species are the most abundant component of assemblages at all stations. Chrysophyte cys...