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a r t i c l e i n f o Keywords: San Andreas Fault SAFOD porosity permeability fault rock composition TEM With transmission electron microscopy (TEM) we observed nanometer-sized pores in four ultracataclastic and fractured core samples recovered from different depths of the main bore hole of the San Andreas Fault Observatory at Depth (SAFOD). Cutting of(More)
[1] Anisotropy of elastic properties in clay-rich sedimentary rocks has been of long-standing interest. These rocks are cap rocks of oil and gas reservoirs, as well as seals for carbon sequestration. Elasticity of shales has been approached by direct velocity measurements and by models based on microstructures. Here we are revisiting the classical(More)
A B S T R A C T Scanning and transmission electron microscopy, synchrotron X-ray diffraction, mi-crotomography and ultrasonic velocity measurements were used to characterize mi-crostructures and anisotropy of three deeply buried Qusaiba shales from the Rub'al-Khali basin, Saudi Arabia. Kaolinite, illite-smectite, illite-mica and chlorite show strong(More)
Coccoliths are calcitic particles produced inside the cells of unicellular marine algae known as coccolithophores. They are abundant components of sea-floor carbonates, and the stoichiometry of calcium to other elements in fossil coccoliths is widely used to infer past environmental conditions. Here we study cryo-preserved cells of the dominant(More)
Boron, discovered as an element in 1808 and produced in pure form in 1909, has still remained the last elemental material, having stable natural isotopes, with the ground state crystal phase to be unknown. It has been a subject of long-standing controversy, if α-B or β-B is the thermodynamically stable phase at ambient pressure and temperature. In the(More)
Zircon (ZrSiO4) is the most commonly used geochronometer, preserving age and geochemical information through a wide range of geological processes. However, zircon U-Pb geochronology can be affected by redistribution of radiogenic Pb, which is incompatible in the crystal structure. This phenomenon is particularly common in zircon that has experienced(More)
The taphonomic nanostructure of acritarch cell walls from the c. 650 million years old Chichkan Formation was studied with optical microscopy (OM), Raman spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), and transmission electron microscopy (TEM). The integration of high-resolution methods and classical optical microscopy(More)
Many organisms form elaborate mineralized structures, constituted of highly organized arrangements of crystals and organic macromolecules. The localization of crystals within these structures is presumably determined by the interaction of nucleating macromolecules with the mineral phase. Here we show that, preceding nucleation, a specific interaction(More)
Gold nanoclusters are small (1-3 nm) nanoparticles with a high surface area that are useful for biomedical studies and drug delivery. The synthesis of small, surface-functionalized gold nanoclusters is greatly dependent on the reaction conditions. Here, we describe a straightforward, efficient and robust room temperature one-pot synthesis of 2 nm gold(More)
In low temperature aqueous solutions, it has long been recognized by in situ experiments that many minerals are preceded by crystalline nanometre-sized particles and non-crystalline nanophases. For magmatic systems, nanometre-sized precursors have not yet been demonstrated to exist, although the suggestion has been around for some time. Here we demonstrate(More)