摘要:

The join CaSiO3—MgO—FeO is a plane through the regular tetrahedron representing the system CaO—MgO—FeO—SiO2. This join cuts the primary phase‐volumes of three interesting series of solid solutions, namely, the magnesio‐wustites (MgO—FeO solid solution), the olivines [monticellite (CaMgSiO4)—iron‐monticellite (CaFeSiO4], and the meliiltes [akermanite (Ca2MgSi2O7)— iron‐akermanite (Ca2MgSi2O7)]. This join also cuts the primary phase‐volumes of pseudowollaztonite (α‐CaSiO3)

ISSN:0002-8606    

DOI:10.1029/TR024i001p00251-3

年代:1943

数据来源: WILEY

摘要:

The recent discovery of the widespread occurrence of helvite, a beryllium‐bearing mineral, at Iron Mountain, New Mexico, has aroused interest in the commercial possibilities of a mineral which heretofore has been considered to have only scientific significance. Helvite contains about 13 per cent beryllium oxide as compared with five to ten per cent beryllium oxide in the mineral, beryl, which at present is the principal source of commercial beryllium. Helvite is consistently distributed, though sparingly in some places, through great masses of contact‐metamorphic rock at Iron Mountain and, therefore, provides great hope for the future when the metallurgical problems have been solved and large‐tonnage, low‐grade ore can be u

ISSN:0002-8606    

DOI:10.1029/TR024i001p00252

年代:1943

数据来源: WILEY

摘要:

In 1907 Cushing [see 1 of “References” at end of paper[ published evidence that dikes of quartz syenite sharply cut the western side of the large Adirondack anorthosite body (or massif), thus indicating a distinctly younger age of the Adirondack syenite‐granite series. He then also described an intermediate rock, lying without sharp contacts, between the anorthosite and the synite, and gave reasons for believing that this rock was a product of assimilation or digestion of anorthosite by syenite

ISSN:0002-8606    

DOI:10.1029/TR024i001p00257-2

年代:1943

数据来源: WILEY

摘要:

Field study of the Modoc Lava Beds in northern California suggest that the simple grouping of the three forms of lava‐surface asaa,pahoehoe, andblock, might well be expanded. The surfaces studied appeared to be of the same general appearance and quality as similar surfaces studied near Mt. Lassen to the south, and on the Hawaiian Islands. Though there should be some common ground of understanding, there is still some doubt and confusion as to what ispahoehoeand what isaa. Most geologists, who accept the terms, will say thatpahoehoeis smooth and thataais rough, and that is correct as far as it goes. During the field study it was noticed that there was a gradual scaling down from very rough or rugged aa to considerably less roughaa. Though still far from smooth, thisaawas much less coarse. In one case these aa projections were found arranged in rows or ropes about six inches apart and it appeared probable that a ropy structure had becomeaaalong the crests.Furroughed aadescribes this somewhat unusual lava‐surface. Curiosity was aroused as to where the line of division between the two types of surface might be, and the field study was modified accordingly. Two methods of attack were adopted, actual measurement and general appearance. In making the measurements, the relief of the points with respect to the cavities was the portion tested (Fig. 1). Except for the glazed surfaces in lava‐tubes and vents, the outer vesicles were not sealed over, leaving the so‐called smoothpahoehoequite rough to the touch. If there were no other projections close by, the relief of the surface would be a little less than that of the diameter of the vesicle. Such measurements as were made onpahoehoewere about equal to, or less than,

ISSN:0002-8606    

DOI:10.1029/TR024i001p00265

年代:1943

数据来源: WILEY

摘要:

The correct interpretation of petrofabric data has been waiting for many years for assistance from the study of experimentally deformed rock‐fabrics. The rock‐deformation at high confining pressures, carried on by David T. Griggs at Harvard University, was an ideal field for such a study and it was agreed to carry out a series of carefully controlled experiments upon definitely oriented rock‐cylinders, whose original fabric had been determined by petrofabric analysis and whose deformed fabric would be studied in the sam

ISSN:0002-8606    

DOI:10.1029/TR024i001p00271-3

年代:1943

数据来源: WILEY

摘要:

In two previous papers, the author has called attention to the possibility of measuring rock‐flowage quantitatively [see 1 and 2 of “References” at end of paper]. Inasmuch as a complete report on the method and its application is delayed due to the emergency, the author feels justified in presenting a brief outline at this time. Oolite deformation in the central Appalachians has been measured systematically under a grant from the Penrose Bequest of the Geological Society of America and a comprehensive report on that work will be published

ISSN:0002-8606    

DOI:10.1029/TR024i001p00273

年代:1943

数据来源: WILEY

摘要:

As there has been no satisfactory method developed to measure and record the orientation of the opaque ore‐minerals, a technique is proposed whereby the orientation of many of the opaque minerals can be measured and statistically recorded on the conventional contoured petrofabric diagram.The method is limited to minerals that have a planar element related to a crystallographic direction that will permit measurement and subsequent recording of the orientation of that crystallographic direction. Some planar elements that can be readily used are: Cleavage; twinning; exsolution plates, when they exhibit relatively sharp boundaries and uniform orientation; crystal faces; replacement or alteration along crystallographic directions; and compositional banding or timing. In many cases etching with the proper solvent will bring out these structures and greatly facilitate the measurement

ISSN:0002-8606    

DOI:10.1029/TR024i001p00280

年代:1943

数据来源: WILEY

摘要:

An investigation of amplitudes of P̅‐waves in southern California in about 300 instances, having epicentral distances from 50 to 570 km, indicates that the velocity V of longitudinal waves in the granitic layer at depths h (in km) between about 2 km and its bottom at about 18 tan is given by V = (5.56 + 0.001 h) in km/sec. The second term is a first approximation only and indicates an increase in the bulk‐modulus by about ¾ per cent corresponding to an increase in pressure by 1000 atmospheres. This is of the same order of magnitude as the values found for granite in laboratory experiments and from the theory of finite s

ISSN:0002-8606    

DOI:10.1029/TR024i001p00281-2

年代:1943

数据来源: WILEY

摘要:

Page 282—In view of possible misunderstanding, the following copy for Figure 1 is to replace that originally published in the article “The interdiurnal variability of temperature on Mount Washington” by V. Conrad (pp. 279

ISSN:0002-8606    

DOI:10.1029/TR024i001p00324

年代:1943

数据来源: WILEY