[1] The >300-km long, east striking Lapeiquan fault lies in the eastern Altyn Tagh range along the northern margin of the Tibetan Plateau and was interpreted as a north dipping thrust in early studies. However, our mapping shows that the fault is a south dipping normal fault juxtaposing Archean-Proterozoic gneisses beneath an early Paleozoic volcanic and sedimentary sequence. Its dip angle vari...

The deformation of sheet-like igneous intrusions in multiple orientations can give detailed insights into the kinematics ductile flow shear zones. Using Torrisdale Vein Complex northern Scottish Caledonides as a case study, we examine relationships between folded and boudinaged pegmatitic deformed by strike-slip dominated shear. Within zone, that trend clockwise adjacent regional foliation were...

IN a previous account (Brown, ~967) of the granitic sheets and veins in the Loch Coire migmatite complex, a metasomatic origin was postulated. This has now been confirmed by new analyses. Read (I93I) described the Loch Coire complex as made of three zones; one of unmigmatized meta-sediments, one of granitic veins and one of 'injection' or migmatite. The sheets and veins of granite (sensu lato),...

First posted October 28, 2022 For additional information, contact: Director, Florence Bascom Geoscience CenterU.S. Geological Survey926A National Center12201 Sunrise Valley DriveReston, VA 20192Contact Pubs Warehouse The bedrock geology of the 7.5-minute Crown Point quadrangle consists deformed and metamorphosed Mesoproterozoic gneisses Adirondack Highlands unconformably overlain by weakly lowe...

Understanding how the Earth’s first continental land masses were generated is important because the processes responsible directly affected the evolution of the planet’s primordial silicate interior, and also its atmosphere and hydrosphere. Archaean continental crust is dominated by rocks of the trondhjemite–tonalite–granodiorite (TTG) suite. These can be divided into (1) a midto late Archaean ...

Cape Roberts Project drill core 3 (CRP-3) was obtained from Roberts ridge, a sea-floor high located at 77oS, 12 km offshore from Cape Roberts in western McMurdo Sound, Antarctica. The recovered core is about 939 m long and comprises strata dated as being early Oligocene (possibly latest Eocene) in age, resting unconformably on ~116 m of basement rocks consisting of Palaeozoic Beacon Supergroup ...