Area Of Volcanic Rocks Research Articles

北陸地方の地質構造と微小地震分布

There are many cases in which microseismicities are connected with active faults. Nevertheless, investigating the spatial distribution of microearthquakes more precisely, it is occasionally revealed that some microseismicities have no clear connections with any active fault, but have some correlations to geological structure. On the basis of this observational facts, an analysis was made on the correspondence between the hypocentral distribution and the geological structure of the Hokuriku district.As a whole tendency, microseismic activities are high in Paleozoic area and they are low in Tertialy and Quaternary volcanic area. Locally, it is recognized that Quaternary volcanic rock areas are specially aseismic and microseismic activities are found around those volcanic areas, and that the granitic areas in Paleozoic area are often aseismic. The sharp spatial contrast of microseismic activities which is not connected with any active fault seems to be resulted from the relative differences of the properties of the neighbouring rocks. The geological structure seems to be one of the control factors of microseismicities.

Stratigraphy and Sedimentation of Redbed Facies in Narrabeen Group of Sydney Basin, Australia

A study of a widespread within the Narrabeen Group of the Sydney basin indicates that the material is a transported laterite that was deposited in a piedmont deltaic environment and was derived from two major source areas. These conclusions are based on paleocurrent data, mineralogic and petrographic data, and geometry and stratigraphy of the redbeds. The Triassic Narrabeen Group has a maximum thickness of 520 m and is dominated by clastic sediments that were deposited in a fluvial environment. The widespread redbeds within the group have a variable thickness. Redbeds of the western Sydney basin, previously uncorrelated with major developments over the eastern part of the basin, are time-equivalent units and hence, sedimentation covered an area of more than 13,000 sq km. These redbeds, which are present near the top of the group, range in thickness from 90 to 180 m and are defined as the redbed facies. The most significant of this is the Bald Hill Claystone in the southern Sydney basin, which was found to correlate with the Wentworth Falls Claystone Member over the remainder of the basin; most of the data presented in this paper are centered around these units. Paleodrainage patterns within the redbed facies were determined on a basinwide scale and restricted to a vertical interval 30 m above and below the base of the Bald Hill Claystone and the Wentworth Falls Claystone Member. At a few widely spaced localities in the western Sydney basin, current data were compiled for complete Narrabeen Group sections. Paleodrainage direction in the section below the base of the Bald Hill Claystone and Wentworth Falls Claystone Member is dominantly southeastward, with an abrupt change in direction to northeast above the base of the units in the southern Sydney basin. A disconformity surface which separates the Bald Hill Claystone from the underlying units resulted when uplift in the south exposed large areas of volcanic rocks. Lateritization and ransportation of this material by the newly developed northerly drainage system yielded the Bald Hill Claystone. Drainage in the northern area of the basin remained unchanged and was southeastward throughout Narrabeen Group sedimentation. From the central area of the basin where the two systems merged, drainage was eastward. Flint clays associated with the redbeds are distributed over three areas of the Sydney basin (the southeastern part, the Blue Mountains, and the Putty area), and occur at the same stratigraphic level. The oolitic flint clays of the southern region (the Garie Formation), which are thought to represent transported bauxitic material, were deposited rapidly on the flanks of exposed bauxitized areas on the eastern and southern margins of the basin. The other deposits, which are more massive and relatively devoid of oolites, represent floodplain deposits formed in low swampy depressions in the western and northern Sydney basin, by an internal drainage system.

Velocity-Porosity Logging in Volcanic Rocks

Velocity-Porosity Logging in Volcanic Rocks

COASTAL TERRACES OF THE SADO ISLAND, JAPAN

The Sado Island with 857 km2 in area is situated in the Japan Sea, about 35 km off Honshu. This islandd consists of two regions, Osado and Kosado. The former region which lies in the northern half is larger than the latter and also higher in altitude, and considered to be a tilted block with steeper foreslopes on the east side. This area is composed mainly of volcanic rocks such as andesite, liperite, basalt, and Miocen green tuff. Surrounding this island are coastal terraces developed widely. The author surveyed these coastal terraces and their deposits in the Osado region, in order to clarify their distribution, altitude, and nature and to consider the geomorphic history. The main results are summarized as follows: 1) The coastal terraces are divided into six plains owing to their altitude and continuity. They are as follows: the first terrace (160-220 m in altitude), second (80-140 m), third (60-120 m), fourth (35-70 m), fifth (25-40 m), and the sixth (5-8 m). 2) These terraces are well developed in the western coastal region in general. On the east side, however, they are no more than a fragmentary distribution. Among the terraces of the Osado region, the third and fourth terraces show a broad and cotinuous distribution. The sixth terrace is also developed all around the island in spite of the limited width. 3) Considering from the thickness and facies of the terrace deposits, the nature of the terrace plains can be classified into four groups. A a In the western coastal region, every terrace plain is of a marine origing formed by striking abrasion of the open sea. B: On the coast along the Mano Bay, the terraces are thought to be of a marine origin formed by the cut and built action of waves in the inland bay. C: In the Kuninaka Plain, the second and third terraces are elevated fans built by the rivers from the northern mountains. On the contrary, the fourth terrace is a dissected coastal plain which consists of thicker neritic sediments deposited in the inland bay. D: In the eastern coastal region, marine terraces are hardly recognized, and most of the flat plains are very small elevated fans consisting of poorly sorted boulders transported by the torrential streams down from the steep slopes. 4) The sixth terrace continues to the alluvial plain of the Kuninaka area, composed of marine alluvial deposits containing the fauna which indicates warmer water temperautre than the present sea in the vicinity and having about 70 m in thickness. Therefore, the formation of the sixth terrace plain is to be correlated with the transgression of early alluvial age which is recognized at many places in Japan. As for the fourth terrace which has a wide distribution and thicker neritic sediments, it may be considered that it was built by the transgression preceeding the regression of the last glacial age just before the alluvial trans-gression. 5) The differences in the character of terrace plains which were mentioned in 3) seem to haue been influenced chiefly by the asymmetry of topography and the condition whether open-sea-facing or not. Rock control is recognized where stacks are found on the terrace plains in the volcanic rock areas of Osado. Concerning the formation of the terrace as a whole, however, it is of the secondary importance, since topographic differences such as those of slopes seem to be the primary differentiating causes. 6) On every marine terrace plain, the elevations of the ancient strand lines increase in an accelerated manner towards the middle part of both sides of the Osado coasts, and this tendency is more evident on the older terraces. This means the upwarping movement with the axis at the middle part of the island has continued since the formation of the first terrace plain.

Discussion

Mr. T. E astwood said that although the paper dealt principally with an area south-east of Ullswater some of the structures to the north of that lake were discussed and he therefore enquired if the author had examined the Skiddaw-Borrowdale junction exposed in the two lowest levels (221 and 237) at the north end of the Greenside Mine and also penetrated by borings. It was reported by Mr. C. Conner, the manager, that there Skiddaw Slates formed one wall of the Greenside Lode, the other being of Borrowdale rocks , that nowhere had he seen both walls of dark slates and that the vein, or at least values, appeared to be cut off by slate. It might be added that the Greenside Lode haded east from 8° to 18°, had been worked over a length of 3500 feet and vertically from outcrop at 2300 feet to about —250 feet O.D. Mr. Eastwood suggested that some of the structural details described by the author might be attributable to the differences between the relatively incompetent Skiddaw Slates and the tougher Borrowdale rocks, as was the case in parts of the Coal Measures in South Wales. Professor S. E. H ollingworth said that when surveying the Eycott Hill area of volcanic rocks on the northern flank of the Skiddaw anticline some thirty years ago, he had made a few traverses on the southern flank around Ullswater in the hope of a quick link up with the northern flank. On Gowbarrow Fell in particular

On the Regional Properties of Hotsprings in Japan

There are another kinds of hotsprings in Japan besides those of Quaternary volcanic areas which are accompanied with fumaroles. Most of them are distrbuted in Tertiary volcanic rock areas, Tertiary plutonic and hyperbyssal rock areas, pre-Tertiary granite areas, Teatiary oil-fields and non-igneous rock areas. Judging from the relation that Quaternary volcanic zones are parallel to those of Tertiary in Japan, hotsprings distributed in above-mentioned areas seem. to be related to Tertiary igneous activities, except a few related to pre-tertiary granite.Chemical characters of hotsprings emitted from altered rock areas are as follows : (1) hotsprings of younger altered rock areas central areas (A) acidic SO4--type (B) acidic Cl--SO4--type outerside areas Cl- type, Cl--SO4-- type and HCO3- type(2) hotsprings of older altered rock areas central area type and Cl--HCO3- type outerside area HCO3- typeAmong them, Cl- type and Cl--HCO3- type of group (2) are charcterized by high content of Cl- 1.5g/1 above and HCO3- 1g/1 above. Through group (1) and (2), hotsproings of outside areas are diluted by ground water and characterized by HCO3- in general.Refering to the genesis of igneous saline waters, hotsprings of Cl' type and Cr-HCO3- type seem to be related to hydrothermal solutions corresponding to hgihly concentrated magmatic waters which were formed below critical temperature under high pressure.The ratio of Na+ to K+ and Br- to Cl-- is characteristic to reveal the regional properties of hotsprings. The ratio of Na + to K+ relates to pH, but there are some hot springs which indicate a wide range of ratio in spite of having constant pH value. The ratio of Br- to Cl- seems avairable to distinguish thermal waters of igneous origin from those of sea water or fossil water origin. Hot springs of volcanic origin are generally characterized by low value. However, some hot springs in igneous rock areas have so high value that it corresponds to that in those of Tertiary oil-fields. The ratio of halogens and alkali-metals in thermal waters may serve as the valuable key to study the regional properties of hotsprings.

Aeromagnetic Study of Copper River Basin, Alaska: ABSTRACT

An aeromagnetic survey was made of approximately 6,000 square miles of the Copper River Basin, Alaska, in 1954 and 1955. North-south flight lines spaced one mile apart were flown from Latitude 61°45^prime to 63°00^prime. The eastern and western borders of the surveyed areas are at Longitudes 145°00^prime and 147°22^prime. The magnetic patterns closely parallel the generally east-west arcuate geologic grain and seem to be correlative with lithology and with geologic structure. Outcropping areas of volcanic rocks are reflected by the configuration of the magnetic contours. A large area of low-amplitude magnetic anomalies extends from the Chugach Mountains north to about Latitude 62°30^prime. This area may possibly outline a structural basin of Tertiary age superimposed upon a depositional and structural trough of Jurassic and Cretaceous age. Anomaly-producing rock masses in this area are estimated to be a mile or more beneath the surface and are interpreted to be most deeply buried beneath the southern part of the Copper River Basin. The magnetic data suggest that lower Jurassic volcanic rocks exposed in the Talkeetna and Chugach mountains underlie the marine and non-marine sedimentary rocks of the southwestern part of the surveyed area. The change in the magnetic pattern at the northern front of the Chugach Mountains is caused by a contact between these volcanic rocks and the younger sedimentary rocks on the north. The magnetic data suggest that the Wrangell lavas of Tertiary and Quaternary age are present at shallow depths beneath the basin in the vicinity of Mount Drum. End_of_Article - Last_Page 219------------

Origin and structural relationships of the igneous member of the livingston formation, Montana

In southwestern Montana north of the Beartooth Mountain uplift and between the north‐flowing Boulder and Stillwater Rivers is an area of volcanic rocks previously known as the agglomerate member of the Livingston Formation [see 1 of “References” at end of paper]. The name Livingston Formation was first applied to about 7,000 feet of sandstones, shales, and conglomerates north and east of Livingston, Montana, but later studies have resulted in considerable remapping of the Livingston as Claggett, Judith River, Bearpaw, Lennep, Lance, and Fort Union formations. Only the original agglomerate member, better called the Igneous member, now remains in the Livingston. These volcanic rocks are one unit of the many upper Cretaceous extrusive rocks in western Montana.

Volcanic sequence in the Marysvale region in southwest‐central Utah

As a consequence of the detailed investigation of the alunite and other mineral deposits of the Marysvale Region in southwest‐central Utah, opportunity was afforded to map and study the succession of volcanic rocks that underlie most of this area. The Marysvale Region is part of a large area of volcanic rocks, which occupies much of the High Plateaus of Utah (Fig. 1). It is believed that the Marysvale Region covers sufficient area to furnish an adequate sample of this volcanic area, and, though horizontal variations are known to occur, the study may serve as a guide as to what may be expected in other parts of the area. The chemical analyses are the most completely representative of any ever taken in this part of Utah, and they furnish a basis of comparison within the High Plateaus and with other areas in Utah.

The Ceja Del Rio Puerco: A Border Feature of the Basin and Range Province in New Mexico: I. Stratigraphy and Structure

The triangular highland known as the Llano de Albuquerque lies in Bernalillo and Valencia counties, New Mexico, between the Rio Grande and the Rio Puerco. Westward it breaks off in a low escarpment called the Ceja del Rio Puerco, which in part forms the western boundary of the Basin and Range Province. The northern 30 miles of the Ceja is a fault-line scarp which marks a series of nearly north-south en echelon faults between the late Tertiary Santa Fe formation and the older rocks of the Plateau Province. Part I.-The Santa Fe consists of fine-grained, alluvial fan deposits. Part of the material was derived from areas of volcanic rocks, but the major portion of it came from the sedimentary rocks of the Plateau Province to the northwest. The boundary of the basin of deposition lay some 10 miles or more northwestward. Ten miles east of this area the Santa Fe consists of river gravel, indicating that the fan deposits were laid down in the western portion of a basin containing a through-flowing river comparable to the present Rio Grande. Four main faults or fault zones, successively offset to the west, separate the Santa Fe from the older rocks. In addition, there are three fault zones within the Santa Fe. Because the Santa Fe is here divisible into three lithologic units, Lower Gray, Middle Red, and Upper Buff members, it has been possible to estimate the minimum throw of these faults and to speculate on the amount of depression of the basin as a result of this faulting.

VII. A Petrographical Sketch of the Carrick Hills, Ayrshire

Introduction. The Carrick Hills form an upland region abutting on the shore of the Firth of Clyde about 6 miles to the south-west of the town of Ayr. They consist of a series of lava flows of Old Red Sandstone age, which are exposed in a magnificent shore section and in many scarps in the interior. There are three principal areas of volcanic rocks in the district. By far the largest is that which forms the Carrick Hills proper. This area is irregular in shape, approximating to a scalene triangle, of which the coast forms one side. The longest direction of extension, E.N.E. from Dunure to a point on the Ayr-Maybole road 2 miles north-west of Dalrymple, is about 6 miles in length. The greatest breadth, from near the Heads of Ayr in a south-easterly direction, is about 2½ miles. The area covered by the lavas must be about 12 square miles. Much smaller areas occur at Culzean and Turnberry. At Culzean the volcanic rocks are exposed in a fine mile-long cliff section, and they have a thinning, faulted extension for about a mile and a half inland towards Mochrum Hill, upon which is a small outlier of lava. At Tumberry is another fine coastal section from Maidens to Turnberry Lighthouse, a distance of 1½ miles. The lavas are confined to a narrow strip along the shore, and any inland extension is masked by broad raised-beach deposits, which are backed by a cliff of Old Red This 250-word extract was created in the absence of an abstract