Recurrent Movement Research Articles

Geology and origin of mineralized breccia pipes in Copper Basin, Arizona

The Copper Basin district, Yavapai County, contains a Cu type Cu-Mo deposit in which the bulk of ore mineralization appears to have been controlled by pipe structures. Mineralization is associated with a composite stock of presumed Laramide age which has intruded older Precambrian metamorphosed sediments and intrusive rocks. The Laramide stock is thought to have an elongated beet shape with a restricted orifice at depth. Its intrusive units range in composition from diorite to aplite, but mineralization appears to be most closely associated with quartz monzonite and quartz monzonite porphyry units. Mineral deposits of the district have a rough zonal arrangement with Cu-Mo mineralization in the center surrounded by an aureole of Pb-Zn-Ag occurrences. Mineralized breccia pipes are roughly cylindrical, near vertical structures ranging in diameter from 50 to 600 ft. A composite pile is composed of a central core of heterogeneous, rotated, angular to rounded rock fragments surrounded by a zone of nonrotated crackle breccia. The fragments are cemented by quartz and may be mineralized with pyrite, chalcopyrite, and molybdenite. The pipes are thought to have been conduits through which late magmatic fluids, collecting near the restricted root of the stock, passed upward. An individual pipe was initiated by passage of fluid upward along a vertical line such as an intersection of faults or fractures. From this channel, fluid worked into the adjacent fractured rocks and corroded fragments that were eventually loosened and moved in the conduit, gradually enlarging the pipe. Quartz later precipitated, filling all of the open space and choking the conduit. Successive flexures of the stock or recurrent movement on regional faults fractured this quartz in some of the pipes, and later hydrothermal solutions tended to follow these conduits, both because of their location on deep-seated structures and because the fractured quartz provided relatively high permeability. Hydrothermal solutions, preceding and accompanying ore deposition, spread outward from the pipes and formed overlapping aureoles of alteration. Pyrite, chalcopyrite, and molybdenite were deposited along fracture surfaces throughout a large area in Copper Basin, but higher grade mineralization was generally confined to fractured pipe structures.

Les caracteres structuraux des montagnes de la region de Kaboul (Afghanistan)

Abstract In the mountains of the Kabul region, Afghanistan, the folded metamorphic basement of undetermined age is unconformably overlain by a thick cover of Permian to upper Cretaceous limestones capped by upper Cretaceous to Lutetian (Eocene) shales and limestones with ophiolites. Following the major orogenic phase, in the upper Nummulitic (Tertiary), deformation of the basement caused dislocations in the cover (folds, thrusts, and important normal faults). Basement deformation involved recurrent movement along faults (generally dipping 45 degrees ) or the thinning of certain less competent beds.

Etude tectonique du massif de la Loube (Var)

Abstract The structure of the Loube massif in Var, France, is typical of the ranges of Provence. The Jurassic cover is divided into a mosaic of independently dislocated segments, reflecting the effects of recurrent movement of basement structures. Development of the mosaic structure and east-west folding in the Cretaceous were succeeded by overthrusting and deformation in the Lutetian-Bartonian (Eocene), with an intervening period of erosion.

Lineaments in Avonlea Area, Saskatchewan

Linear features revealed by air-photo mosaics of the Avonlea area are due to topographic relief, stream adjustments, alignment of elongate closed basins, vegetation, and soil-moisture differences. They occur in two sets parallel with known faults and some appear to coincide with faults mapped at the surface. They are therefore regarded as lineaments, which are the surface expression of faults. The fault pattern, the position and great length of some faults, and the location of the epicenter of a very strong earthquake are advanced as arguments for a tectonic origin of the faulting. Minor faulting due to the removal of Middle Devonian salt by solution, may have taken place after the deposition of the salt. Large faults of tectonic origin, which appear to be responsible for the Missouri Coteau, are probably basement faults along which recurrent movement has taken place. Fault traps of hydrocarbons in pre-Middle Devonian units are possible, although the apparent displacement of older strata may not be as much as that in younger rocks.

Tectonics of Colorado Front Range: ABSTRACT

The Colorado Front Range is the largest structural and topographic element in the eastern Rocky Mountains. Its axis parallels the northerly trend of the mountain front through central Colorado. Two additional trends are recognized in the Colorado Rockies. A northwesterly zone of uplifts extends from the Apishapa arch to the Uinta Mountains. A similar, but more vaguely expressed, northeasterly zone localizes a belt of Laramide igneous intrusives. These regional trends constitute the tectonic framework within which the Front Range evolved. Fragmentary data on the structure of the basement complex suggest a probable relation between Precambrian and later structures. Paleozoic and Mesozoic crustal movements and sedimentation accentuated and modified Precambrian structural trends. In general the sedimentary cover was relatively thin, but locally thicknesses exceed 15,000 feet. Certain positive elements may have persisted from ancestral Rocky Mountain time into the Cretaceous. Associated with the northeast-trending belt of Laramide intrusives in the central part of the Front Range are northeast- and northwest-trending steep faults that appear to form a conjugate system of shears. Recurrent movements along these faults were complex and displacements noted along the margins of the range are in places opposite to those observed in the crystalline core. Along the northeast flank of the range, the northwesterly faults cut the sedimentary rocks and produce en echelon folds. Except along the northeast flank, the Front Range is bounded by reverse faults and thrusts that dip toward the mountains. The range was wedged upward along these faults, and adjacent sedimentary basins were depressed during Laramide time. Thrusting was most prominent adjacent to and within those areas which had received the greatest thicknesses of pre-Laramide sediments. End_of_Article - Last_Page 786------------

Sur l'age et l'extension des terrains houillers dans la terminaison sud de Belledonne (dome de La Mure et regions annexes); leurs rapports avec le socle cristallophyllien

Abstract The Carboniferous coal-bearing sequence in the southern Belledonne massif area, France, has previously been assigned only to the Stephanian A. Westphalian beds have been identified at the base of the sequence, separated from the overlying strata by a conglomerate. They are considered to have been deposited in a broad syncline between two zones of high relief resulting from crustal movements during the Sudetic phase of the Hercynian orogeny. Following recurrent crustal movements, the Stephanian sediments were deposited in a slightly broadened syncline. The folded and faulted coal basin was further compressed and fractured during Alpine orogenic activity.

Golden Trend of South-Central Oklahoma

The Golden Trend of south-central Oklahoma is located principally in western McClain and Garvin counties, Oklahoma, in the Southeastern embayment of the Anadarko basin, bounded on the east by the Nemaha-Pauls Valley uplifts, and on the south by the western Arbuckle Mountains. Although broad gentle warping and truncation occurred during Hunton, Mississippian, and early Pennsylvanian time, the great orogenic movements that originated the Arbuckle-Wichita structural system occurred in post-Morrow pre-Deese (Des Moines) time with northwest en echelon faults formed as adjustments to the westward-plunging arches, which was accompanied by major east-west faulting. The descent into the Southeastern embayment of the Anadarko basin is accomplished by the successive down-dropping of fault blocks. Approximately 15,000 feet of pre-Deese sediments were locally truncated in the highest areas to expose the basement complex. The region was eroded to approach base level but was later strongly down-warped to initiate the Anadarko basin and permitted onlap of the Deese sediments which reached a probable maximum thickness of 3,500 feet in the deeper basin areas on the west and lapped out completely on the Pauls Valley uplift. This progressive marine onlap was further modified by the preservation of scarps where faults were rejuvenated so that areas of abrupt thickening and thinning occur where the invading seas failed to reduce to base level the structural relief across fault blocks, or where movement occurred subsequent to the peneplanation and prior to deposition of the Deese sediment . Recurrent movements continued into later Hoxbar time, but, in contrast to the pre-Deese faulting, only minor warping occurred in the succeeding Pennsylvanian redbeds. Oil is produced from rocks varying in age from the Permian to the Ordovician. Three type oil fields are described in detail. The main producing formations are various Deese (Pennsylvanian) sandstones, upper (Devonian) and lower (Silurian) Hunton limestone, Viola (Ordovician) limestones, and several formations of the Simpson group (Ordovician). Several pools produce from the Simpson group in structural traps, but most of the pools in the area produce from Deese sandstones in stratigraphic traps formed by these sandstones as they successively lap out upon the Pauls Valley uplift. Here the geologist has had an unparalleled opportunity to find stratigraphically trapped oil, and by subsurface studies he has been able to direct exploration to this end. His successes are indicated by the rem rkable discovery rate. The enormous reserves uncovered within the last 4 years have focused national attention to the province. Future prospecting offers even more encouraging results.

La faille de l'Arve au viaduc Sainte-Marie (Les Houches, Haute-Savoie)

Abstract A polished surface covering some 30 square meters of Carboniferous rock exposed in the vicinity of the Sainte-Marie viaduct in the Aiguilles Rouges massif, Haute-Savoie, France, represents a plane of the Arve fault along which renewed movement had taken place. The absence of mineralization along the fault indicates that the recurrent movement was post-Alpine.

Societies and Academies

Societies and Academies

Die Periodischen Bewegüngen der Blattorgane

THE essential character of periodic movements as defined by Pfefifer is their being recurrent. All “repeated” movements, whatever their cause and mechanism may be, are periodic. Recurrent or periodic movements are of different kinds, and it is necessary carefully to distinguish between them. Thus certain periodic movements occur only during the growth of the part, and cease entirely when the structure has become full-grown; and the term “nutation” is restricted by Pfeffer to these recurrent movements during growth. In other cases periodic movements occur which are not determined by the growth of the part, but are due exclusively to the elongation and contraction of certain portions of tissue; and these latter are called by Pfeffer “movements of variation.” These movements of variation which occur so commonly in the Leguminosae are due to the action of more or less joint or hingelike portions of the leaf. Nutations on the other hand which occur in very many leaves or petioles are due to unequal growth of the tissues, and not to the presence of a joint. As the movements of nutation are dependent on the growth of the part, they cease when growth ceases; and as the zone of maximum growth of the part changes its position, so also the seat of the nutation will vary. The movements of variation have a very different character, as they continue when the leaf is full-grown, and naturally, as they depend on a definite structure having a fixed position, they do not change their place during growth. The two forms of movement are very closely related, and jointed parts during growth often exhibit movements of nutation, thus showing the close relationship that exists between the two. Die Periodischen Bewegungen der Blattorgane. Von Dr. W. Pfeffer, A.O., Professor in Bonn. Mit 4 lithographirten Tafeln und 9 Holzschnitten. (Leipzig: verlag von Wilhelm Engelmann, 1875. 8vo., 176 pp.) (The Periodic Movements of Leaf-organs. By Dr. W. Pfeffer, Extraordinary Professor in Bonn. With 4 lithographed plates and 9 woodcuts. Leipzig: W. Engelmann.)