Horizontal Veins Research Articles

Small-scale positive flower structures

Field relations indicate that small-scale positive flower structures along sub-regional strike-slip faults localize ore in particular 4 m thick, bedded ore zones in Mississippi Valley-type Pb-Zn deposits of the Viburnum Trend, southeast Missouri, U.S.A. Outwardly divergent, shallow-dipping, duplex-deformed fault splays control ore and merge inwardly with sub-vertical fault strands. The characteristics of both duplex-deformed splays and ore suggest that the flower structures acted as drains for fluids being moved vertically along the strike-slip faults. This ore control differs from pipe-like conduits of transtensional dilation jogs in that duplex-deformed splays form under transpression and develop horizontal veins adjacent to strike-slip faults.

Computerized tomography and ultrasound in the noninvasive evaluation of coarctation of the aorta

In 1 patient the diagnosis was further confirmed at operation. Normal pulmonary venous connection to the left atrium can usually be identified by 2-D echo in 3 views: apical, subcostal and suprasternal.1,3*5 However, failure in demonstrating pulmonary venous connection to the left atrium cannot by itself be construed as evidence for abnormal pulmonary venous drainage. Hence, demonstration of a dilated common pulmonary vein, usually behind the left atrium, is of paramount importance in the diagnosis of TAPVC. To achieve this, proper gain settings and careful scanning of the pulmonary veins in different echo planes by apical, subcostal and suprasternal approaches are mandatory, lest a diagnosis of normal pulmonary venous drainage be falsely made. This is exemplified in our experience with both patients. When examined initially from the subcostal position, we had a false impression of normal connection of the right upper pulmonary vein with the left atrium. Visualization of a dilated descending common pulmonary vein in the liver with subsequent scanning provided a clue for the diagnosis of TAPVC. The small, alleged pulmonary vein most likely represented 1 of the horizontal veins behind the left atrium just above the diaphragm. False connection of this pulmonary vein with the left atrium probably resulted from poor image resolution in this particular subcostal view. In a deeper subcostal cut of the long axis of the 2 atria, a mildly dilated pulmonary venous confluence, clearly separated from the left atrium, was demonstrated.

FOLDED PERMIAN GYPSUM OF RIPON PARKS, YORKSHIRE

Summary The Upper Permian Marl at Ripon Parks contains a disturbed series of reddish marls and gypsum overlying banded grey gypsum; folded or horizontal veins of fibrous gypsum are common, particularly in the red beds. The gypsum porphyroblasts of the grey and red gypsum rocks invariably contain relict anhydrite. The complex folding of the red beds is ascribed to the readiness with which gypsum flows under stress. The following history is deduced: development of gypsum porphyroblasts and fibrous gypsum as overburden is removed from anhydritic rocks; folding along west to north-west axes; conversion of the remainder of the anhydrite to fine-grained gypsum; faulting along north-west to north lines.

On the origin of veins in asbestiform serpentine

Introduction As a result of a recent trip to Thetford mines, in Canada, the writer was able to secure for the National Museum, and through the courtesy of Mr B. J. Bennett, manager of the King Brothers mines, an unusually fine block of serpentine, with veins of the fibrous form, chrysotile (the so-called asbestos), which seems worthy of a special description, even though little, if anything, new is deduced relative to the origin of the material. Description of the Specimen The block, as now on exhibition in the Museum (plate 33), is some 30 by 30 by 27 inches (76.2 by 76.2 by 68.6 centimeters) in dimensions. As seen in the plate, it is traversed from left to right by one large vein of the asbestos (chrysotile), with others not quite so wide, in an approximately vertical direction. Confining our attention first to the horizontal vein (some 40 millimeters in . . .

XVII. Notes on the Pitchstone at Corriegills, Arran

Mr. Ramsay, in his well-known little work on the Geology of Arran, published just thirty years ago, referring to “the largest and most important of all the pitchstone veins” on the eastern side of the island—that which occurs on the Corriegills shore—contented himself (contrary to his usual practice) with quoting Dr. Macculloch’s “minute description” of it, which is as follows:—“It resembles so strongly a mass of prismatic trap, as to be often overlooked in walking along the shore, even by those who have been directed to the spot. From its horizontal position, it has been by some called a bed; but, like traps in similar cases, it may with propriety be considered a horizontal vein. The visible face is rudely prismatic, and about 12 feet thick, extending for about 200 yards, and terminating abruptly at each end. It is apparently conformable to the sandstone on which it lies; but whether rigidly so, cannot be discovered, as the faces of the cliffs are obscured, both by the mouldering of the rocks, and by dispersed patches of vegetation. Like the sandstone, it reclines to the south-west at an angle of about 30 degrees. Its texture is tolerably uniform throughout, being most commonly also lamellar, and it is of a dark or bottle-green colour. It is not accompanied by any visible disturbance of the adjoining sandstone, nor is there any apparent change in either rock at the places of contact; except that, as happens so frequently among the trap rocks, the vein decomposes This 250-word extract was created in the absence of an abstract