Coronal holes,solar wind streams,and geomagnetic activity during the new sunspot cycle

We have extended our previous study of coronal holes, solar wind streams, and geomagnetic disturbances from the declining phase (1973–1975) of sunspot cycle 20 through sunspot minimum (1976) into the rising phase (1977) of cycle 21. Using daily He I 10830 Å spectroheliograms and photospheric magnetograms, we found the following results:

1. As the magnetic field patterns changed, the solar atmosphere evolved from a structure having a few, large, long-lived, low-latitude coronal holes to one having numerous small, short-lived, high-latitude holes (in addition to the polar holes which persisted throughout this 5-year interval).
2. The high-latitude holes recurred with a synodic rotation period of 28–29 days instead of the 27-day period already known to be characteristic of low-latitude holes.
3. During 1976–1977 many coronal holes were intrinsically ‘weak’ in the sense that their average intensities did not differ greatly from the intensity of their surroundings. Such low-contrast holes were rare during 1973–1975.

An updated Bartels display of the occurrence of holes, wind speed, and geomagnetic activity summarizes the evolution of their characteristics and interrelations as the sunspot cycle has progressed. Long-lived, low-latitude holes have become rare but remain terrestrially effective. The more common high-latitude holes are effective only when the Earth lies at a relatively high heliographic latitude in the same solar hemisphere.     

Regular precessions of a gyrostatic satellite in a circular orbit

In the present paper, the regular precessions about the mass center are studied, for a Volterra-type gyrostatic satellite in a circular orbit under a Newtonian force field. All the possible regular precessions are determined.     

A new model for X-ray emission from NGC 4151

We present an analysis of the reported spectral features of NGC 4151 in X-rays. It is shown that the origin of X-rays from the source is inconsistent with a single production mechanism. We suggest a new two-component model in which soft X-rays arise from the black-body emission of a tiny hot nucleus withT2×10⁷ K and the hard X-ray photons are generated in an extended region by inverse Compton scattering of electrons with the infrared photons.     

Lower Cambrian patch reefs and associated sediments: southern Labrador, Canada

The complex pattern of biological accretion, internal sedimentation, early lithification, and biological destruction, that characterizes modern reefs and many fossil reefs has been recognized in archaeocyathid-rich patch reefs of Lower Cambrian age in the Forteau Formation, southern Labrador. Patch reefs occur as isolated masses or complex associations of many discrete masses of archaeocyathid-rich limestone and skeletal lime sands, surrounded by well-bedded skeletal limestones and shales. Each reef is composed of many loafshaped mounds stacked on top of one another. The limestone of each mound comprises archaeocyathids and Renalcis or Renalcis-like structures in a matrix of argillaceous lime mud rich in sponge spicules, trilobite and salterellid skeletons. Numerous growth cavities roofed by pendant Renalcis-like organisms and Renalcis are partially to completely filled with geopetal sediment indicating that much of the matrix was deposited as internal sediment. Two stages of diagenetic alteration are recognized: (1) syn-depositional, which affected only the reefs, and (2) post-depositional, which affected both reefs and inter-reef sediments. On the sea floor reef sediments were pervasively cemented and fibrous carbonate was precipitated in intraskeletal and growth cavities. These limestones and cements as well as archaeocyathid skeletons, were subsequently bored by endolithic organisms. Later post-depositional subaerial diagenesis resulted first in dissolution of certain skeletons and precipitation of calcite cement above the water table, followed by extensive precipitation of pore-filling calcite below the water table. These carbonate reefs are similar in structure to the basal pioneer accumulations of much younger lower and middle Palaeozoic reefs. They did not develop into massive ‘ecologic’ reefs because archaeocyathids never developed the necessary large, massive, hemispherical skeletons. This occurrence indicates that reefs developed more or less coincident with, and not long after, the appearance of skeletal metazoans in the Lower Cambrian.     

Molecular weight distribution of humic and fulvic acids of sediments from a north Florida estuary

The molecular weight distribution of the humic and fulvic acid fractions of two sediments was determined using Amicon ultrafiltrat ion techniques. All fractions of humic substances had a molecular weight range of less than 500 to greater than 300,000. The largest component of humic acids was in the greater than 300,000 molecular weight range, whereas, the largest percentages of fulvic acids were in the less than 500 molecular weight range and the 100,000–300,000 molecular weight range. From this preliminary investigation there appears to be a qualitative relationship between the molecular weight composition of the humic substances in the sediment and the salinity of the overlying water within an estuarine environment.     

Primary fractionation of elements among iron meteorites

The primary fractionation process in iron meteorites is that responsible for the distribution of elements between the groups, most notably Ga and Ge, which show concentration ranges of 10³ and 10⁴ respectively. To investigate the cause of the primary fractionation, concentrations of 16 elements were converted to relative abundances by dividing the element/Ni ratio by the CI chondrite ratio. These abundances were plotted on logarithmic graphs with data for each group (except IB and IIICD) and each cluster of closely related anomalous irons averaged.Co, P, Au, As, Cu, Sb, Ge and Zn are positively correlated with Ga. For most groups (except IA, IC and IIAB) relative abundances of these elements tend to decrease from about 1 in approximately the order listed above. This is the expected order in which these elements will condense into Fe, Ni during equilibrium nebular condensation. Mean relative abundances of refractory elements in groups generally lie within a narrow range of 0.5–2, and are uncorrelated with Ga. Although the equilibrium model may be only a gross approximation, it suggests that most primary fractionation did occur during nebular condensation.The anomalous irons are essential for defining many of the primary fractionation trends. On several element-Ga graphs the displacements of the anomalous irons from the primary curves indicate that these irons experienced the same secondary fractionation process (probably fractional crystallization) that produced the trends within most groups. The anomalous irons appear to be samples from over 50 minor groups, which have similar histories to the 12 major groups.     

Fair weather and storm sand transport on the Long Island, New York, inner shelf

Both spring-summer and fall-winter sand transport have been observed on the Long Island, New York, inner shelf at water depths of 20-22 m using a radio-isotope sand tracer system. The extent of dispersal of the tagged, fine sand was measured at 3 week intervals in two 70 day experiments. In the late spring and early summer, movement was primarily diffusive in nature, extending 100 m around the line of tracer injection, while late fall-winter patterns had strong advective features, including an ellipsoidal outline extending approximately 1500 m westward of the injection points after the passage of several storms with strong northeasterly winds. Near-bottom current observations made with Savonius rotor sensors identify the event responsible for the bulk of the transport over the 135 day observation period as a storm flow of 2 days duration. Tracer and current observations together suggest that westward winter storm flow along the Long Island shelf is the major mechanism of sand transport at these depths on a yearly time scale. A least-squares fit of several of the observed winter patterns with a plume model yields average sediment mass flux lower bounds of 3.2 × 10^?3 gm/cm/sec and 1.7 × 10^?1 gm/cm/sec for ‘typical’ and extreme winter storm activity.     

Calcretes of Olduvai Gorge and the Ndolanya Beds of northern Tanzania

Pedogenic calcretes are closely associated with Pliocene to Holocene wind-worked deposits of volcanic ash in the Olduvai and Ndolanya Beds of northern Tanzania. The typical profile with calcrete consists of an unconsolidated sediment layer, an underlying laminar calcrete, and a lowermost massive calcrete. The laminar calcrete is a relatively pure limestone, whereas massive calcrete is aeolian tuff cemented and replaced by calcite. An Olduvai calcrete profile can develop to a mature stage in only a few thousand years. Carbonatite ash was the dominant source for most of the calcite in the calcretes. Replacement was a major process in formation of the massive calcretes, and oolitic textures have resulted from micrite replacing pelletoid clay coatings around sand grains. Phillipsite and possible other zeolites were extensively replaced in the massive calcretes. Replacement of clay by micrite in the Olduvai calcretes is accompanied by dissolution or leaching of phengitic illite and the formation of clay approaching the composition of halloysite or kaolinite. In the upper calcrete of the Ndolanya Beds, montmorillonite was altered to a kaolinite-type mineral and to dioctahedral chlorite. Authigenic dolomite, zeolite, and dawsonite in the Olduvai calcretes probably received at least some of their components from replaced materials.     

Tectonics and sedimentation a century later

This paper is one of a series that commemorates the fiftieth anniversary of the founding of the Society of Economic Paleontologists and Mineralogists in 1926. At that time, thought about tectonics and sedimentation was dominated by the ruling hypothesis of continental accretion. Marginal geosynclines were thought to have been filled with sediments derived from borderlands of Precambrian rocks, and then welded tectonically to the continent. In the 1930s, the fundamental distinction noted by Bailey and Jones between graded graywacke- graptolitic slate suites and cross-bedded sandstone-shelly carbonate suites provided a prelude to Krynine's petrographic-tectonic sandstone clans. In the 1940s sedimentary petrography finally emerged from its heavy mineral era to broaden its vistas. Prior notions of evolutionary successions of sediment types linked to a supposed tectonic cycle (e.g. the European ophiolite-flysch-molasse sequence) became more explicit. Refinements of sandstone classifications by Folk, Pettijohn, Gilbert and others, coupled with Krynine's tectonic cycle and the stratigraphic syntheses of Krumbein, Sloss, Dapples, and others, led in the 1940s to the belief that tectonics is the ultimate sedimentary control.Meanwhile the geosyncline had been dissected by Stille and Kay (1936–1951). Ideas about sources of geosynclinal sediments and paleogeography were revised to include volcanic islands and tectonic lands raisedwithin geosynclines rather than borderlands of Precambrian rocks standing outside the geosynclines. In the 1950s and 1960s, sedimentologists exploited the turbidity current revolution and the combined paleocurrent-petrographic approach pioneered by Pettijohn to delineate in detail the paleography and provenances of orogenic belts. Provenance studies have recently reached a high level of sophistication thanks to the efforts of many workers (e.g. Blatt, Crook, Dickinson, Füchtbauer, McBride, Schwab, Suttner, etc.). This work has demonstrated clearly that the cratonic, volcanic and tectonic source land types proposed by Kay had all been important, but to varying degrees at different times and places. When plate tectonics arrived in the late 1960s, sedimentologists were all equipped to reinterpret their rocks using petrographic, paleocurrent and sedimentary structure analyses to help diagnose different types of plate boundaries and to aid in making palinspastic plate restorations. Thus the study of tectonics and sedimentation is alive and thriving a century later.