Argille Scagliose Research Articles

Origin of Large Overturned Slabs of Apennines, Italy

Slabs with inverted sedimentary sequences are present in the chaotic terranes (argille scagliose) of the Apennines. Previous investigators suggested that the inversion of the sequences took place during the gravity sliding of the argille scagliose. The working hypothesis presented herein postulates two episodes of deformation. Recumbent folds were formed during the early Tertiary. The inverted slabs originally were a part of the inverted limb of the folds. An erosional interval ensued, during which erosion removed the upper limbs of some recumbent folds. Late Tertiary deformation was characterized by more pervasive shearing, i.e., the land-slipping movement. The previously formed recumbent folds were fragmented during this movement. Large fragments of the limbs of the fol s are now preserved as slabs enclosed by the argille scagliose. Slabs which originally constituted the inverted limb contain thus only inverted sedimentary sequences; other slabs contain only normal sequences. Geologic observations of the Monghidoro region in North Tuscany clearly indicate two episodes of deformation separated by an erosional interval. The early Tertiary recumbent folding hypothesis also helps clarify the geologic interpretations of East Liguria.

Stratigraphy of Producing Geothermal Fields: ABSTRACT

Natural steam production is found in reservoir rock overlain by impervious cap rock. These rocks may be volcanic, sedimentary, metamorphic, or plutonic. The age and composition of these rocks are not important but only Pliocene and Recent magmas are known as an underlying heat source. Reservoir rocks usually are highly fractured and rendered porous by solutions, must be of sufficient thickness (minimum 100 meters), and of an areal extent to sustain continuous production. Porosity values should be at least 10 per cent. Man has utilized natural steam and hot waters throughout historic time. There are many present-day uses for natural heat, such as wood-pulp manufacture, evaporation of salt, space heating, and greenhouse farming. The first electricity made from natural steam was in 1905 at Larderello, Italy. Iceland, New Zealand, and Japan also were early users of geothermal energy. The Geysers in California is the first and only geothermal field generating electricity in the United States. Pacific Gas and Electric installed the first 12,000-kwh. turbine-generator in 1960, a 14,000-kwh. unit in 1963, and in 1966 installed a 27,500-kwh. unit for a total of 53,500-kwh. capacity. A fourth unit is planned in 1968 bringing the total to 81,000 kwh. The rapid industrialization and population growth of the we tern states, as well as the world, has led to increased demands for energy. The U.S. Bureau of Mines Circular 8230 states that, if the growth in electric energy consumption occurs as projected, construction of considerably more thermal-generating plants will be required. Natural steam probably is the cheapest source of energy. Potential geothermal resources of steam are evacuated by five fundamental criteria: (1) source of heat; (2) regional and local structural features; (3) source of meteoric waters (to infiltrate and circulate to depth); (4) reservoir rock sufficient to retain geothermal fluids in volume; and (5) impervious cap rock overlying reservoir for trapping steam. Facca and ten Dam recommend exploration in four stages: 1. Preliminary survey and selection of area (includes geological, geophysical, and geothermal information, stratigraphic studies, and porosity and permeability data). 2. Detailed survey of selected area (includes photogeology, volcanological and petrographic studies, hydrogeochemistry, and hydrogeology and gradient surveys). 3. Test drilling. 4. Probing and evaluating (includes output measurements and production tests). Stratigraphic data of three producing geothermal fields for comparison are given. Larderello field, Tuscany, Italy, discussed by Facca (1963). He described the sequence and conditions as follows: (1) basement rock, quartzitic and anagenetic; (2) reservoir rock, evaporitic dolomite with high porosity and permeability, Late Triassic; (3) cap rock, flysch-like, shaly, impervious argille scagliose, Late Cretaceous-early Miocene age; (4) no Recent volcanoes; (5) heat flow provided by a deep-lying magma; (6) temperature of producing zone is 200°C. (392°F.); and (7) surface hydrothermal activity occurs as hot springs and steam jets of 100° to 190°C. (212° to 374°F.). Wairakei field, North Island, New Zealand, was described by W. G. Grindley (1961) as a volcanic region 240 kilometers long, a Recent graben filled exclusively by volcanites. Two volcanoes are active at each end of the graben. The impervious Huka Formation is the controlling factor in heat accumulation. The producing End_Page 477------------------------------ aquifer is the Waiora Formation, a porous pumice breccia with buried flows of andesite in the lower part. Underlying the reservoir is the Wairakei Ignimbrite Formation, consisting of impervious dense ignimbrite sheets. The Geysers, California, was described by McNitt (1963) as having Pleistocene and Pliocene volcanic vents, with rhyolite flows and tuffs, basaltic, dacitic, and andesitic lavas in outcrop in the hydrothermal area. The stratigraphic sequence consists of (1) Cretaceous, massive, yellow-brown sandstone and gray shale 1,700-3,000 meters thick; (2) Knoxville Formation (Upper Jurassic), thin-bedded graywacke and shale, intruded by 150-300 meters of serpentine sills, thickness 1,700 meters; and (3) Franciscan Group (Upper Jurassic), interbedded graywacke and spilitic basalt, and small amounts of shale, conglomerate, and chert; intruded by serpentine sills; thickness, 9,000 meters. The Mesozoic rocks were folded gently, then intensely faulted. Surface thermal activity consists of hot springs, fumaroles, and hydrothermal rock alterations. The producing zone is a sandstone in the Franciscan, shattered severely by faulting, and altered by hydrothermal activity. The sandstone is dense, indurated, with some interbedded shale. Fractures to 0.5 inch wide have been cored. The BHT average is 208°C. (401°F.), pressure is 60 to 150 psi. End_of_Article - Last_Page 478------------

On the geology of the Indoburman ranges

Abstract The mountains of western and northwestern Burma consist chiefly of colossal accumulations of Palaeocene to Eocene (Arakan and Chin Hills) or Senonian to Eocene (Naga Hills) Flysch of varying, including “exotic”, facies. The main frontal thrust zone of the Alpino‐Himalayan Tectogene lies along and within the easternmost ranges of this Indoburman system, not along the western margin (Shan Scarp) of the Sinoburman Highlands. Some of the highest mountains in the Naga Hills are “Klippen” of metamorphics lying on Flysch. The Flysch ranges arose during the Oligocene but along the Arakan Coast there is ample evidence of an equally important earlier orogenic phase (latest Cretaceous) now almost totally buried beneath the western half of the Indoburman system and the post‐Oligocene “Argille Scagliose” and “Macigno” on‐lapping eastwards from the Bengal‐Assam embayment. The lowlands of Central and Lower Burma do not represent a foreland feature, but an intramontane Molasse‐filled basin to which the sea retai...

Gravity Tectonics Near Passo Della Cisa, Northern Apennines, Italy

A selected area was studied to evaluate the hypothesis of far-traveled gravity slides in a part of the Northern Apennines. The backbone of the Northern Apennines south of Passo della Cisa consists of strong, autochthonous macigno sandstone (Oligocene); it is a horst, devoid of structural cover. Adjoining on the west, a lower macigno block is structurally overlain by allochthonous remnants. North and east of the horst, widespread allochthonous materials form a thick cover which presumably once mantled the entire area prior to block faulting. The complex allochthon comprises argille scagliose and dispersed masses of competent limestone, sandstone, and sandy siltstone. The shale matrix and the enclosed competent masses are remnants of Cretaceous, Eocene, and Oligocene formations of various penecontemporaneous facies. One extensive mass of black shale in the argille scagliose represents a single semi-coherent formation. This shale shows appreciable structural homogeneity, and small overturned folds within it indicate movement of the allochthon toward the north, east, and southeast. The writer is convinced that gravity is the only agent that could have moved the allochthon. One plate of rock more than 4 by 7 km is apparently separated from its sources by intervening weak shale, so that it could hardly have been pushed laterally. Most of the competent blocks in the allochthon are not in contact with one another and have drifted apart rather than forming a train capable of transmitting a lateral “push from the rear.” This seemingly eliminates any alternative to gravity as the propulsive agent.

On Some Turkish Sediments

Attention is drawn to the similarity of certain sediments or breccia beds of exotic composition in Turkey to the Argille scagliose formation of Italy, and the explanations that have been given for them. The similarity of a white chalk exposure near Sile to the typical upper Chalk of Europe is noted, in view of the fact that paleogeographic maps do not show the Chalk sea reaching beyond the Crimean-Caucasus region. The discussion by McCallien points out that these items have been considered previously and that as far as the Argille scagliose is concerned, he and Bailey still favor a tectonic interpretation.

Clay Minerals of the Argille Scagliose of the Modenese Apennines

Samples of the argille sca.eliose from various localities in the Modenese Apennines have been studied by optical, X-ray and d.t.a, methods as part of an investigation into the composition and origin of this remark- able allochthonous formation. Illite, chlorite and a kaolinitic mineral of fireclay type are widespread. Samples from one locality contain also a conspicuous 22-28 .~ swelling chlorite, the origin of which is discus- sed. It is as yet mlcertain whether this mineral is confined *.o clays containing exotic blocks of ophiolite (grcenstone) or whether it is more widely distributed. A programme of work on the allochthonous clays of the Apennines, financed by the National Research Council of Italy, has been under- taken in order to investigate the composition and characteristics of these sediments; and if possible to determine their age and the con- ditions under which they were originally deposited. This work, started in 1942, has involved two separate lines of research. The palaeontological side has been largely developed by E. M. Gallitelli, the mineralogical-petrological aspects by the author and his co- workers (see Gallitelli and Gallitelli 1949). The allochthonous formation known as the argille scagliose con- sists of a shaly matrix in which are enveloped exotic blocks of basic igneous material (ophiolites), limestones, sandstone and other rocks. The whole sequence is regarded by Merla (1951) as material which has slid eastwards in gigantic 'orogenic landslips during the elevation of the Apennines. Neither its original position in the geosyncline nor its age are known with certainty. The investigations described in this paper were made on samples of the argille scagliose from Varana, Sassomorello and Castelvecchio in the Modenese Apennines. They were collected close to enveloped blocks of ophiolite (gabbro, diabase or serpentine) and consist of red and grey clays both of which contain arenaceous foraminifera of Upper Cretaceous age (E. M. Gallitelli 1943 (a) and (b), 1947). These clays have been separated by suspension in water into fractions with a particle size of 30-12tz, 12-5/z, 5-1tz and 1-0.1t, for optical, X-ray and d.t.a, examination. RESULTS

Scientific Serials

THE Sitzungsberichte of the Vienna Imperial Academy of Sciences (Natural History Section, vol. Ixxvi. parts 1—5, and vol. Ixxvii. parts 1—4) contain the following more important papers:—Addenda to our knowledge of annelids, by Dr. Aug. v. Mojsiso-vics.—On the orthoptera of the Senegal River, by Dr. H. Kraus.—On the fauna of the Cypris slates of the Eger tertiary strata, by O. Novak.—On the natural history of glimmer, by G. Tschermak.—Researches on cystolithes and some similar formations in the vegetable kingdom, by K. Richter.—On the genesis of salt deposits, particularly of those in western North America, by F. Posepny.—On the fresh-water fish of South-Eastern Brazil, by Dr. F. Steindachner.—On the “Salse di Sassuolo” and the “Argille scagliose,” by Theodor Fuchs.—On the flora of the countries round the Mediterranean and their dependence from the soils, by the same.—On the fossil flora of Parschlug, in Styria, by Dr. C. von Ettingshausen.—On the development of the embryo of Asplenium shepherdi, S pr., by F. Vouk.—On the internal cells in the antheridium cell of the pollen gram of certain coniferse, by A. Tomaschek.—On the origin of aptychus-Hmestone, by Th. Fuchs.—On the light line in the prism cells of seed scales, by Dr. R. Junowics.—On the encircled specks in the wood of trees, by Dr. J. Kreuz.—On the firmness and elasticity of vegetable tissues and organs, by Th. Weinzierl.—On the resinous ducts of certain coniferae, by Dr. Kreuz.—On the development of the pollen of Colckicum autumnale, L., by A. Tomaschek.—On some accessory appendages to the skull of Leporidse, by Dr. A. von Mojsisovics,—On cork and cork tissues, by Dr. F. von Höhnel.—Histo chemical researches on xyllophiline and coniferine, by the same.—On the phanerogamic flora of the Sandwich Islands, by Dr. H. W. Reichardt.—On the protoplasm of the pea, by Dr. Ed. Tangl.—On the undulating nutation of the internodes of the stems of plants, by J. Wiesner.—On the behaviour of Phloroglucine and of some similar substances towards the woody cell membrane, by the same.—On the degeneration in the leaf-shoots of some Amygdalese, caused by species of Exoascus, by E. Rathay.-Researches on Tunicata, by C. Heller.—On some new genera and species of Neuroptera, by Dr. F. Brauer.—On the originals to Ign. von Bern's Testaceis Musei Csesarei Vindobonensis, found in the Imperial Zoological Museum, by the same.—On the embryology of ferns, by H. Leitgeb.—Geological researches in the western part of the Balkan and the surrounding districts, by Franz Toula.—On some peculiar apertures in the corolla leaves of Francjscea macrantha, Pohl, by M. Waldner.—On the basaltic lava of the Eifel Mountains, by E. Hussak.—On the origin of holes and inden. tures in the leaf of Philodendron pertusum, Schott, by F. Schwarz.—Ichthyological researches, by Dr. F. Steindachner.—On the subterranean water-courses and basins, a.s well as on the clearness and transparency of certain lakes, and on the formation of lakes generally, by Dr. A. Boué.