17 research outputs found
Characterisation and beneficiation of zircon-rich heavy mineral concentrates from Central Kalimantan (Borneo, Indonesia)
Investigation of structural and electrical properties of silico-ferrite of calcium (SFC) in the Fe2O3–CaO–SiO2 system synthesized by solid-state reaction
Refinement of iron ore sinter phases: a silico-ferrite of calcium and aluminium (SFCA) and an Al-free SFC, and the effect on phase quantification by X-ray diffraction
Mineral alteration and pore-plugging caused by acid in situ leaching: a case study of the Wuyier uranium deposit, Xinjiang, NW China
Intersector element partitioning in tourmaline: a potentially powerful single crystal thermometer
Combining compositional zoning and foliation intersection axes (FIAs) in garnet to quantitatively determine early P-T-t paths in multiply deformed and metamorphosed schists: north central Massachusetts, USA
Quantitative compositional and microstructural analysis of garnet porphyroblasts in kyanite–staurolite–garnet grade rocks from the northeastern flank of the Pelham dome, north central Massachusetts, distinguishes the effects of Acadian deformation and metamorphism from extensive overprinting Alleghanian shearing. The P–T conditions and the metamorphic path during the Acadian were determined using samples preserving well defined stages in a lengthy tectonic history revealed by a succession of five foliation intersection axis trends preserved within porphyroblasts (FIAs). This Acadian succession extends at least 120 km to the north into rocks where no evidence has been found of an Alleghanian overprint. For each sample where garnet first nucleated during one of these stages in the tectonic history, the PT of core growth was determined by plotting the intersection of the Mn, Fe and Ca isopleths calculated for the core composition on a P–T pseudosection for that sample using THERMOCALC. Combining the PT data from all these samples indicates that the temperature and pressure increased throughout Acadian orogenesis, causing episodic garnet growth. During the Alleghanian, locally intense shearing, especially against the margin of the Pelham dome, formed the dominant schistosity, which truncated all foliations defined by inclusion trails in porphyroblasts and obliterated all remains of Acadian deformation and metamorphism in the rock matrix. Shearing was accompanied by near complete homogenization of the compositional zoning in garnet porphyroblasts and an associated apparent increase in the temperature of the matrix to 700°C in those rocks lying directly adjacent to the Pelham dome, and resulted from the rocks of the Northfield syncline being thrust a large distance southwards over the gneisses in the dome