Depression Zone Research Articles

Electrophysiological mechanisms underlying rate-dependent changes of refractoriness in normal and segmentally depressed canine Purkinje fibers. The characteristics of post-repolarization refractoriness.

Tissues from diseased hearts are known to exhibit post-repolarization refractoriness and rate-dependent changes of the refractory period that are often inconsistent with changes in action potential duration. To examine the electrophysiological mechanisms responsible for such rate-dependent changes of the refractory period, a narrow inexcitable zone was created by superfusing the central segments of Purkinje fibers with an "ion-free" isotonic sucrose solution. The degree of conduction impairment could be finely regulated by varying the resistance of the extracellular shunt pathway. At intermediate or low levels of block, the refractory period remained unchanged or decreased, respectively, as the rate was increased. At relatively high levels of block, however, we observed marked increases of the refractory period in response to increases in the stimulation rate. The disparity of refractoriness between normally conducting fibers and fibers exhibiting discontinuous conduction characteristics and post-repolarization refractoriness increased dramatically as a function of increasing stimulation rate. With the aid of current clamp techniques, we demonstrate that the differential behavior is due to the interplay between rate-dependent changes in the restitution of excitability at the site beyond the depressed zone secondary to changes in passive and active membrane properties and in the intensity of local circuit current provided to that site by activity generated in the segment proximal to the zone of block. Our data suggest that rate-dependent changes of refractoriness in Purkinje tissue are principally governed by attendant changes in membrane resistance.

Geology of Petroleum in Kohat-Potwar Depression, Pakistan

The 36,000-km2 Kohat-Potwar depression in northern Pakistan has more than 5,000 m of marine deposition (Precambrian to Eocene, with a major break during Ordovician to Carboniferous). More than 10,000 m of Miocene to Pleistocene alluvial sediments overlies the marine sequence. The tectonic depression formed as a result of continent-to-continent collision at the northwestern margin of the Indian plate. Although the region has been under active petroleum exploration since the mid-nineteenth century, it has been tested by only 60 exploratory wells. Ten oil fields have been discovered; original recoverable reserves total 200 million bbl, of which 112 million bbl has been produced. The region has several attractive features for petroleum generation and accumulation i cluding source-reservoir-trap assemblages and thermal maturity regimes. Total ultimately recoverable hydrocarbon resource of the area is estimated at 2.4 billion bbl of oil equivalent. Many unexplored surface and subsurface prospects and stratigraphic leads are known. Parts of the region, particularly the Bannu depression and Kohat salt zone, can be regarded as frontier areas; based on the exposed geology and available seismic information, we believe these areas are promising. Recent discoveries of Dakhni field (1983) and Dhurnal field (1984), which were the first discoveries in the northern part of the platform zone of the Potwar plateau, and production from Paleozoic horizons have added new dimension to petroleum prospects of the area. The region needs careful reevaluation of available information, exploratory drilling on selected targets, and detailed exploration in its western part.

Basin formation along the Bocono‐Moron‐El Pilar Fault System, Venezuela

Within the boundary zone between the Caribbean‐South America plates, which includes the Boconó‐Morón‐El Pilar right‐lateral fault system that has been active since the late Tertiary, there are several sedimentary basins in the Venezuelan Andes and the Caribbean Mountains. These were formed in zones of crustal depression, where faults diverge, and as pull‐apart basins in zones of en echelon stepovers (or along releasing bends) in the faults. In addition, there are pull‐apart basins along the Avila and La Victoria faultzones in the Caribbean Mountains, which are associated with the plate boundary. The basins are filled with alluvial, lacustrine, fluvial, and marine sediments, mainly of Quaternary age. On the basis of model studies, dimensions of the basins, and age of their sedimentary fill, it is estimated that right‐lateral offset necessary to form them along the Boconó‐Morón‐El Pilar fault system varies from 2 to 125 km. Along the Avila and La Victoria fault zones, this right‐lateral offset is estimated to range from 2 to 30 km. On this basis, the maximum right‐lateral offset along the southern Caribbean plate boundary that can be documented along the Boconó‐Morón‐El Pilar fault system has not exceeded 100–125 km. If there has been larger offset, it has to be documented by other means, or it has taken place along other fault zones within the system.

Reflected reentry in nonhomogeneous ventricular muscle as a mechanism of cardiac arrhythmias.

Arrhythmogenesis in ventricular muscle exhibiting nonhomogeneous excitability was studied in isolated tissues from feline and canine hearts. Longitudinal bundles were mounted in a three-chambered bath and simultaneous transmembrane recordings were obtained from fibers in each chamber. Nonhomogeneous excitability was established by depressing only the central segment (1 to 2 mm wide) with high-K+ Tyrode's solution, which induced discontinuity of propagation associated with step delays mediated by electrotonic current flowing through the depressed zone. When transmission delays were long, activity distal to the site of block returned to proximal tissue as one of two forms of reflected reentry, each elicited by a different mechanism. Type I reflection, occurring with antegrade delays of 30 to 60 msec, was characterized by an early secondary depolarization due to electrotonic spread of currents from delayed responses in the depressed segment. Type II reflection evolved with delays greater than 90 msec and was manifest as a closely coupled regenerative action potential that developed independently of a pacemaker mechanism and of slow but continuous conduction. We conclude that delayed activation of excitable elements, which occurs when propagation is discontinuous, may lead to rhythm disturbances of focal origin that are mediated by electrotonic interactions across a zone of depressed tissue.

Part-time farming in Cyprus

Part-time farming may be viewed as a part of the process of labour migration out of agriculture associated with economic growth and development. It helps to sustain the rural sector by reducing the rate of out-migration. This paper reports on a pilot survey of part-time farmers in the Greek speaking ‘government-controlled’ part of Cyprus. The survey findings suggest that in Cyprus part-time farmers are slightly younger and operate smaller holdings than average; they rent in less land and irrigate a smaller area. There are substantial differences between the agricultural zones. In coastal fruit- and vegetable-producing areas, commercial part-time farming complements off-farm work which is available locally. The farmers' confidence in their long-term prospects is reflected in their willingness and ability to invest on the farm and in low levels of out-migration. In the relatively depressed mountain zone, off-farm work is necessary to supplement family income, and debts are incurred for consumption purposes. Farmers travel long distances to find work and may have more than one off-farm occupation. Much of the burden of farm work falls on other family members. Although mountain farmers would like to spend more time in agriculture they have little confidence in its future prospects and expect their children to migrate. Government support may be necessary in such areas to ensure the survival of rural communities.

中央日本南部の第四紀地殻運動 地殻運動の変化と場の移動

Various opinions on the Quaternary tectonism previously pointed out are discussed and summarized as follows:1) The tectonic culmination in the middle Quaternary is not at least an extensive phenomenon at this area.2) The uniform rate of deformation in the Quaternary seems to be accepted in the order of less than 105yrs, but not likely in the order of more than 106yrs.3) Although the accelerated rates towards the present are often suggested by many recent studies, these may be an apparent feature due to a fluctuation in a relatively short time span within a long-term displacement, or due to a change from a long-wave (or extensive) deformation to a short-wave (or limited) deformation. And also may result from a growing process, as typically expressed with formative advance of fault, even in a same stress condition.4) The SW Japan has been under the regional stress field of WNW-ESE compression through the Quaternary, being originated from the subduction of oceanic plates.5) The shallow depression along the median zone of SW Japan had come into existence simultaneously with the subduction along the Nankai Trough from the middle Pliocene. This may suggest the rejuvenation of the Philippine Sea Plate from that time.6) The leading edge of the underthrusting slab of the Philippine Sea Plate locates at the outer zone in the active segment of the Median Tectonic Line, whearas it extends to the inner zone in its inactive segment (Fig. 4A). These indicate that the outer zone underthrust at very low angle (ca 10°) by the plate behaves as a rigid bloack. As such belts as the outer zone, the longitudinal depression zone and the upwarping mountain of the inner zone have gradually shifted to the northwestward with the times (Fig. 4), these systematic migrations of tectonic province with miscellaneous changes of its process are likely caused by an advance of the underthrusting slab.7) The landward tilting terraces along the Pacific coast of SW Japan are considered to be caused by reverse faults which have emerged as accretionary prism on the upper part of continental slope from the middle to late Quaternary.

Formation and distribution of gas-oil accumulations in the Paleozoic subsalt deposits of the northern marginal zone of the Caspian depression

We consider the formation and distribution of the gas--oil (gas-condensate) accumulations in the upper Paleozoic subsalt deposits of the northern marginal zone of the Caspian depression. On the basis of a detailed analysis of the geological, geochemical, and other conditions of preservation and conversion of the disseminated organic matter (DOM), we conclude that the principal sources of the hydrocarbons (HC) are the Devonian--Middle Carboniferous oil-source sequences. A result of the complex (stepped) migration of the hydrocarbons from these deposits, accumulations of oil and gas (gas-condensate) were formed in the Middle Carboniferous--Lower Permian deposits. From factual geological--geophysical and geochemical data, and also the results of sampling deep exploratory wells (the West Teplovo area), there is a possibility of discovering tectonically screened deposits of oil and gas in the marginal sectors of the basin, confined to the sunken blocks of structures and associated with faults in the subsalt Paleozoic sequence.

REGIONAL CHARACTERISTICS AND THEIR GEODYNAMIC IMPLICATIONS OF LATE QUATERNARY TECTONIC MOVEMENT DEDUCED FROM DEFORMED FORMER SHORELINES IN JAPAN

In the Japanese coastal area, deformation patterns deduced from the height of former shorelines are classified into four types, A, B, C and D, each reflecting different response of tectonic regions to island arc movements. Each area has been progressively and acceleratedly deformed in a same pattern during the late Quaternary. Maximum rate of average uplift is 1.5m/1, 000 years for the Last Interglacial terrace and 4m/1, 000 years for the Holocene terrace.The landward tilting, type D, on the Pacific coast of Southwest Japan has been associated with great earthquakes occurring below the inner slope of the Nankai Trough. Type D area is separated from upwarping mountains by hinge lines along which subsidence has accumulated. Tectonic basins filled with younger sediments on the continental slopes are assumed to be depressed zones along the former hinge lines. Ages of deformed shorelines suggest that until the early Pleistocene seismic deformation had affected only the continental slopes and later propagated onto the coastal area in the late Pleistocene at the latest, resulting in the intensification of deformation of former shorelines. In contrast, type C deformation has predominated on the Pacific coast of Northeast Japan, which are 200km distant from the Japan Trench and seem to be still located landward of hinge lines of seismic crustal movement.

FAULT TOPOGRAPHY AND QUATERNARY FAULTING ALONG THE MIDDLE AND EASTERN PARTS OF THE ARIMA-TAKATSUKI TECTONIC LINE, KINKI DISTRICT, CENTRAL JAPAN

The Arima-Takatsuki Tectonic Line (ATL), located on the northwestern rim of the Kinki Triangle, is an active fault zone developed along the geologic boundary separating the Tanba Zone of Paleozoic rocks to the north and the Ryoke Zone of granite to the south. Along the middle and eastern parts of this tectonic line, limiting the northern border of the Osaka Plain, displacements of terrain features, mainly terrace surfaces (dissected fans), due to fault activities can be clearly observed. The writer has investigated these displaced topographies and attempted to elucidate the nature of fault activities of the middle and eastern parts of the ATL. The findings can be summarized as follows. 1) Faults in this area, trending either E-W or ENE-WSW, can be classified into three types, those having: 1) displaced terrace surfaces vertically, and valleys cutting these surfaces dextrally, such as Kiyoshikojin and Satsukioka Faults; 2) formed shallow depression zones such as Hanayashiki, Koyaike and Ibaraki Depressions in the E-W direction on the terrace surfaces; and 3) cut through and displaced valleys in the mountains on the north, such as Ishizumitaki, Satsukioka, Minoo and Nyoidani Faults. 2) Rates of displacements have been computed by estimating ages of the terrace sur-faces and valleys dissecting these surfaces; for type 1), 0.5-1.5m/103 years dextrally and 0.06-0.2m/103 years vertically, and for type 2), a maximum of 0.8m/103 years in vertical direction. 3) The active fault system of the Rokko Mountains is continuous to that of the study area. Active faults of both regions are distributed in the shape of E-W extending wedge, with the tip pointing to the eastern end of the study area. These fault systems have been active in the second half of the Quaternary under the stress field of E-W compression. Accordingly, NE-SW trending faults have greater amounts of vertical displacements than ENE-WSW trending faults, with both having dextral movements. 4) The Median Tectonic Line (MTL), bordering the base of the Kinki Triangle, is also an E-W trending geologic boundary. Along active faults associated with the MTL, the rates of displacements both in vertical and dextral directions are twice as great as those found for the active faults of the ATL. Distribution of type 3) faults of the ATL is similar to that of the MTL in the sense that both are located on the northern side of geologic boundaries.

Paleomagnetism of samples from the axial zone of the Afar depression

A series of oriented lava flows has been collected for paleomagnetic work from an axial graben situated in the Afar depression. This graben has many geophysical and structural features which suggest a similarity with the median valleys found in many mid-oceanic ridges. The results of the paleomagnetic work show that all the samples collected from the graben have normal magnetizations. This, coupled with the fact that they are obviously very young, suggests that they were emplaced during the Brunhes normal epoch of the earth's magnetic field. A series of four older lavas was sampled. These lavas gave directions just below the horizontal, but with easterly declinations. These directions could have been caused by a deviation of the earth's field from its normal axial dipole direction, or they could be caused by large-scale rotation about a vertical axis. This rotation could be connected to the distortion necessary to close up the continental portions of crust around the Gulf of Tadjoura.

The Relationship between the Landform and Crustal Movement in the Southwestern Part of the Shonai Plain

The paper deals with the relationship between the landform and crustal movement of the Ohyama River delta plain in the southwestern part of the Shonai Plain, and the depression zone on this delta plain. The results are summarized as follows:The alluvial plain of the Ohyama River is composed mainly of delta plain. To the west this alluvial plain adjoins the Kamo moutains, and to the south Yakushidake and Sanbokura mountain blocks. The Akagawa floodplain, the eastern boundary of this alluvial plain, coincides with a tectonic line running from north to south, which divides the Shonai Plain into the eastern and the western parts. Judging from landform, alluvial geological structure, bedrock geological structure and gravity anomaly distribution, the author is certain that this delta plain corresponds to a trough between the tectonic line above and that at the east of Kamo mountains.The trough forming movement has continued throughout the making of delta plain, and is partly reflected in the results of repeated precist levelling.Moreover, the 10-15m contours on this plain show a depression zone in the same direction with the Kamo mountains.Under this depression zone, a synclinal movement of the Kamigo formation, which comprises the eastern part of the Kamo mountains, has been continuing even after the formation of delta plain.This movement has brought the undulation on the plain surface such as a down-warping with dimensions of 1-1.5km by about 9km.According to the results of repeated precise levelling from 1956-1966, including the crustal movement caused by the Niigata earthquake, the bench mark located closest to this depression zone is still dropping.Therefore, the author concluded that the depression movement of the Ohyama River basin is still going on in the recent geological time. The Ohdo River flows south-southwest to north-northeast on this depression zone.

Precordial ST-segment mapping 4. Experience with mapping of ST-segment depression in anterior transmural myocardial infarction

In order to assess the relative significance of precordial ST-segment elevations and depressions, 32 patients with anterior transmural myocardial infarction were studied utilizing serial 49-lead precordial maps. Theoretically, zones of ST-segment depression adjacent to major zones of ST-segment elevation might represent border areas of mild ischemia, and hence could be more readily amenable to intervention therapy. As expected, an extensive zone of ST-segment elevation was observed precordially in each of these patients. However, zones of ST-segment depression in adjacent areas were noted to occur inconsistently, were limited in distribution and magnitude, and bore no fixed relationship to zones of ST-segment elevation. Thus, mapping of precordial ST-segment depression in anterior transmural infarction probably has a limited role in assessing evolution of ischemic injury or therapy in these patients. This finding does not, however, vitiate the significance of ST-segment depressions in angina, intermediate coronary syndrome, or non-transmural infarction, conditions which may deserve further study using mapping techniques.

Possible evidence of a cultural practice affecting head growth in some late pleistocene east Asian and Australasian populations

It is well known that a number of cultural practices can leave their mark on the skeletonas altered morphology or incisions. Deformed head and foot shapes, tooth removal or modification for aesthetic or ritual reasons are well known However, the evidence for these human behavioural traits is generally to be found in material dated only to the past few millennia. A possible exception could be cranial deformation, the result of pressure influence on bone modelling during childhood. This may be of two kinds: (a) accidental, the result of variable head covering or cradle devices which could have long term influence on some aspect of cranial growth; (b) intentional modification by the application of well designed “binding” or “boards”, resulting in the squaring off or elongation of the vault. Although intentional deformation as a widespread cultural trait has been well reviewed by Dingwall (1931) and more recent authors, little attention has been given to the possibility of minor and accidental external influences on head growth. Yet the possibility arises that this could have occurred commonly in some communities who ornament or cover their heads in certain ways. Moreover, it is clear that any slight changes resulting might all too easily be missed with the result that multivariate analyses of measurements from such skulls might present a very distorted picture of actual population affinities. Furthermore, such misinterpretation becomes especially dangerous in the case of fragmentary fossil and sub-fossil hominid material. As yet, there have been no claims that the skull morphology of Pleistocene communities might be affected by such cultural agents, but it in fact seems possible to present a case for accidental head deformation in at least the late Palaeolithic period of eastern Asia. The evidence comes from three sites, as follows: (a) Upper Cave site. Choukoutien, China. This is probably the earliest evidence so far of minor frontal deformity. In the so called “Melanesian woman” the skull is in a relatively good state of preservation and shows a slightly depressed zone extending laterally across the upper part of the frontal roughly from one temporal line to the other. The anomaly is seen in good lateral views of the skull [Figure 1 (b)], but as the extent of the shape change is minimal, it is understandable that it has previously been missed. In view of the generally good condition of the skull, it seems unlikely that this localized variation is the result of post mortem deformity.

ON THE AREAL VARIATION OF LAND AND ITS UTILIZATION PATTERNS IN THE STATE OF PRAIBA, NORTHEASTERN BRAZIL

This paper is an approach to the analysis of land and its utilization patterns in Northeastern Brazil. It was based on the field observations of the multiple relationship existing between natural environment and human activities. The Department of Geography, Tokyo Kyoiku University, planned a field study of Northeastern Brazil, and sent the research missions to this area three times, sponsored by the Japanese Ministry of Education. The first field study was carried on from December, 1966 to February, 1967, the second from January to March, 1971, and the third from December, 1972 to February, 1973. This report outlines the results of field observation in the third field study, mainly in the state of Paralba. Many geographers have established the areally corresponding relationship between natural environmental factors and land use. Our research group, including myself, proposes a division of land use regions in the state of ParaIba. This consists of three regions and ten subregions as follows: 1) Zona da Mata a) Coastal lowland. b) Tabuleiros. c) Varzea (Rio de Acucar). 2) Agreste d) Peripheral Tabuleiros. e) Depression Zone (low relief plain formed on crystaline rock). f) Borborema Massif. g) Brejos. 3) Sertao h) Cariris. i) Piranhas basin. j) Alto-Sertao.

Plastic Deformation in Cracked Plates of Low-Carbon Steel under Monotonic Tension and Cyclic Tension-Compression

Specimens of 0.03%C steel with a crack of the length 1.5 or 3mm were subjected to the cyclic tension-compression of amplitude 10 or 13kg/mm2 or to the monotonic tensile stress 10 or 13kg/mm2. In each case, the following three parameters defining the plastic deformation ahead of the crack tips were measured by means of optical microscopy and the back-reflection X-ray microbeam diffraction method, i. e., (i) the depressed zone size, (ii) the slip band zone size and (iii) the distribution of the excess dislocation density in the vicinity of the crack tips. The plastic deformation in cracked plates was compared in terms of these microscopic parameters. The results obtained are summarized as follows:(1) The size of the depressed zone formed ahead of the crack tips under monotonic loads was accurately predicted by Dugdale's equation. The increase in the excess dislocation density was detected in the depressed region, the maximum value being reached at a small distance away from the crack tips. The maximum stress in the depressed region evaluated from the excess dislocation density was smaller than the lower yield strength of the material.(2) As to the plastic deformation due to cyclic tension-compression, the depressed zone was observed in the specimen under a high stress intensity factor, but not under low stress intensity factors. The antinucleation in the depressed zone under low stress intensity factors may be caused by the following reasons: (i) the strain rate in the cyclic tests is higher than that in the monotonic tests, (ii) the work-hardening of the material at the crack tip due to cyclic stress is higher than that due to monotonic stress, and (iii) the compressive residual stress exists near the tip of fatigue cracks. The excess dislocation density took the maximum value at the crack tip, and its value is several times as large as that under monotonic stress. The flow stress of the material at the crack tip under cyclic stress is nearly twice as high as that under monotonic stress.(3) Slip bands were not observed in the vicinity of the crack tips of the specimens that were deformed under monotonic loads, while they were observed near the tip of fatigue cracks. The zone of slip bands near the crack tips does not correspond to the monotonically deformed zone, but to the cyclically deformed zone.

Mechanism of the Wedensky phenomena in the left bundle branch

In a man with acute myocardial infarction, second degree atrioventricular (A-V) block with the Wenckebach phenomenon was observed. Paradoxically, only the first sequence beat showed left bundle branch block; beats conducted after shorter R-R intervals had normal intraventricular conduction. The most likely explanation of this, and of 2 earlier similar cases, is that Wedensky facilitation follows the beat that terminates a long R-R interval and allows the passage of the next descending impulse through the left bundle branch; the Wedensky effect allows the conduction of any further impulses that pass the A-V node to arrive at the depressed zone while the enhancing mechanism is still operative. An extrapolation of certain properties of conduction in nerve allows this hypothesis: electrotonic (physical) potentials spread through and beyond the depressed zone in the wake of the blocked, propagated (biologic) impulse. Further electrotonic potentials invade the depressed area from the antidromic invasion of the distal left bundle, and also from nearby fibers. These potentials summate to raise the resting potential of the zone of block nearer to threshold, and thus facilitate conduction. Conditions most provocative of this phenomenon would appear with a small patch of disease in a bundle branch. This is consonant with previous clinical, pathologic and electrocardiographic experience.

FEATURES OF SUNFLOWER BIOPRODUCTIVITY IN INFLUENCE ZONE OF FOREST BELTS

Sunflower occupies considerable acreages and is one of the principle species for vegetable oil production in Russia, so the specificities of its growing in the systems of forest belts with the use of no-till technology are to be studied. The research was conducted in Mikhailovsky and Ilovlinsky areas, the Volgograd region. The main research object was the sheltered sowings of sunflower hybrid LG-5456 on southern chernozems with the use of no-till technology in different vegetation phases. The comparative data on sunflower variety Rodnik grown on light-chestnut soils by the common technology is presented. The unique scheme of fields observation was used which was based on the system analysis and study of the patterns of agrophytocenoses functioning in the zone of forest belts influence. The data on leaves area, assimilating surface, and photosynthetic activity were obtained. The leaves area during the three years of research has reached its maximum values in 2016, wherein there was its burst caused by abundant rainfalls and registered in July, 12, 2017, in the zone of depression at a distance of one height (1H) of the forest belts. In the droughty 1999 the maximum quantity of leaves of the variance Rodnik in the phase of full ripeness was at a distance of 5H and equaled 21, and decreased up to 16 in control site. The analysis of assimilating surface in timing displayed its changes in logistic dependence. The photosynthetic potential of sunflower in space at a different distance from forest belts changes in exponential dependence. The said characteristics provide the prediction of species development. The harvest quality indices of sunflower hybrid LG-5456 grown by dry farming in the zone of windbreaks influence were obtained. The weight of 1000 grains reached the maximum value of 59.27 g in 2016 at a distance of 15H and 45.06 g in 2017 at a distance of 30H. The diagnosis of mineral nutrition in sunflower plants was carried out. The insufficiency in boron content at a distance of 10H in 2017 resulted in the stopping of the development of flowers and decrease in weight of calathides, number of grains per calathide, weight of 1000 grains which affected the indices of oil content and seeds fullness.

Continental drift and thermal fields

The moving apart of platform regions during a continental drift results in large depressions in which the more intensively heated deep-seated masses approach the earth surface. It is natural that major thermal anomalies originate in these areas. According to the ideas of mobilism, a classical example of the moving apart of continental blocks is the continental drift associated with the dissociation of the western and eastern hemispheres and their falling apart. The major depressions formed between them became filled with oceans (the Atlantic. the Indian Ocean, etc.) producing their spectacular cooling effect. Thus, though the more intensively heated deep-seated masses approached the earth surface as a result of the moving apart of the platforms, major positive thermal fields should have been produced here. However, the cooling influence of the oceans diminished this effect substantially, often reducing it to a minimum or eliminating it altogether. Major thermal fields originating as a result of the moving apart of platforms could be retained and maintained most of all within land boundaries but not in oceanic regions. The author suggested an idea concerning the West-Siberian continental drift ( Tamrazyan 1963) in the course of which the ancient moving apart of the East-European and Siberian platforms had occurred with resulting large tectonic depressions between them where the so-called continental plates (the West-Siberian, Turan, and Skif plates) had been formed during geological history. The intensive tectonic sagging within these depressions produced favourable conditions for the intake of erosion products from the surrounding vast territories. As a result of such a process very thick beds of terrigenous deposits having high heat resistance were formed in these depressions. This in turn contributed to the origination and retention of major positive heat anomalies here. All the most important high-temperature regions of the USSR (the West-Siberian, Turan, and Caspian lowlands, the pre-Caucasus, the Kuban lowland, the Crimea Steppe and other regions) are situated just between the moved-apart edges of the West-Siberian ruptured joint and in its branchings. This is in relation to a paradoxical phenomenon consisting in the fact that the interior of the cold West Siberia is much more heated than the interior of the not so cold and temperate-climate medium-latitude areas as well as many southern areas of the East-European plain located 1500–2000 km to the south. In West-Siberia coincident with the depression zone between the East-European and Siberian platforms which have been moving apart, a sharp displacement of high-temperature regions in the northern direction takes place at the same hypsometric levels (at depths of 0.5; 1; 1.5; 2 km or more below sea level). The continental drift ideas are also of practical importance with regard to the use of the interior heat of the earth, as they outline wast areas characterized by sharply intensified heat fields.

KARAKTERISTIK MINERAL LEMPUNG HASIL UBAHAN PADA SUMUR LW-1 DAN LW-2 DENGAN MENGGUNAKAN METODE DIFRAKSI SINAR-X PADA SISTEM PANAS BUMI GUNUNG LAWU

Sumur panas bumi LW-1 dan LW-2 yang terletak pada zona depresi antara Gunung Lawu dan Gunung Jabolorangan memiliki batuan yang telah mengalami ubahan hidrotermal, dicirikan dengan mineral-mineral ubahan yang tergolong ke dalam tipe ubahan argilik-argilik lanjut. Untuk mengetahui karakter mineral ubahan yang terbentuk, khususnya kehadiran mineral lempung pada sumur LW-1 dan LW-2, maka diperlukan studi mengenai mineral lempung dengan menggunakan pendekatan metode difraksi sinar-X (X-Ray Diffraction/XRD). Penelitian ini bertujuan untuk mengetahui keterdapatan dan karakteristik mineral lempung pada sumur LW-1 dan LW-2 serta hubungannya dengan pembentukan sistem panas bumi di daerah Gunung Lawu. Penggunaan metode XRD pada sumur LW-1 dan LW-2 menunjukkan bahwa pada saat temperatur mengalami peningkatan maka bentuk kristal dari mineral lempung semakin sempurna yang kemudian diikuti oleh semakin kecilnya nilai derajat kristalinitas, sedangkan pengaruh ukuran butir pada pola XRD memperlihatkan bahwa derajat kristalinitas mineral lempung cenderung mengalami penurunan seiring dengan bertambahnya ukuran butir. Mineral lempung hasil ubahan pada sumur LW-1 dan LW-2 terdiri dari smektit, illit, kaolinit dan haloisit yang dapat berfungsi sebagai lapisan penudung dalam sistem panas bumi Gunung Lawu.

Evaluation of operational reserves of high temperature waters

Exploitational resources of geothermal steam are at present evaluated on the basis of the experimental-exploitational outlet of steam-water mixture. During exploitation it has been stated that steam-water wells, such as ordinary hydrogeological wells, influence the pressure high-temperature water-bearing complex, causing the depression of stratum pressure. It is shown on the concrete example, that the evaluation of exploitational resources of thermal waters for a certain period of exploitation of a deposit may be done by definition of piezometric level sinking according to the unstable filtration formula. In the operating steam-water wells, in connection with the movement in the upper part of steam-water mixture trunk, it is difficult to determine the sinking of the level and dynamics of its change with time ( t). Hydrological parameters were evaluated on the data of the level restoration (s) after experimental outlet of the steam-water mixture, considering the observed dependence: S = f ( lgt) Exploitational resources after a short-time outflow of the thermal waters through the wells are provided mainly by a mass of heated water, which is located in the upper part of hydrothermal systems and constantly regenerated. Continuous exploitation of the systems is maintained by outflow of the heat, which is located in the heated rocks in the limits of thermal anomalies, and by the inflow of the goethermal deep-seated steam to the zone of depression of the strata pressure with intensive outflow of the mass and heat from the upper horizons. This explains the considerably greater heat capacity of the artificial outflow in comparison with the natural heat capacity of hydrothermal systems. The obtained regularities of the discharge change or level sinking in the process of the experimental outlets of the steam-water mixture, or a short-time exploitation, may be used for evaluation by the hydrodynamic method of the maximal resources of the thermal deposits. This will afford the possibility to evaluate correctly the possible capacity of geothermal power stations in the initial period of prospecting and accelerate the preparation of the deposit for exploitation.