scholarly journals III.—On some British Pillow-lavas and the Rocks associated with them

1911 ◽  
Vol 8 (5) ◽  
pp. 202-209 ◽  
Author(s):  
Henry Dewey ◽  
John Smith Flett
Keyword(s):  
Lava Flow ◽  
External Surface ◽  
Igneous Rocks ◽  
Pillow Lavas

The pillow-laves are a group of basic igneous rocks that occur, in our experience, only as submarine flows, and very frequently exhibit ‘pillow-structure’. A lava-flow of this type is composed of sack-shaped masses, globular or elongated, and varying in size. The external surface of the pillows may be compact, but in their interior there are numerous cavities often concentrically arranged. First described in Britain by Nicholas Whitley (1), and figured also by De la Beche (2), they have become generally known through the work of Teall (3), Raisin (4), Reid and Dewey (5), and their importance among the Palæozoic eruptive rocks of Britain is now well established.

Paleointensity derived from igneous rocks of Kamchatka volcanoes of the Late Pleistocene-Holocene epoch

2020 ◽  
Author(s):  
Iuliia Sleptsova ◽  
Valeriy Maksimochkin
Keyword(s):  
Magnetic Field ◽  
Curie Temperature ◽  
Lava Flow ◽  
Geomagnetic Field ◽  
Single Domain ◽  
Igneous Rocks ◽  
Lava Flows ◽  
Virtual Geomagnetic Pole ◽  
Temperature Oxidation ◽  
Curie Temperature Tc

<p>This work is devoted to paleomagnetic studies of lava samples from three volcanoes of Kamchatka in order to define the age of lava flows and to obtain data of paleosecular variations of the geomagnetic field for the Kamchatka region. We studied 53 samples from 7 sites from lava flows of the Avachinsky, the Gorely and the Tolbachik volcanoes. The study of paleosecular variations recorded in the magnetization of the lava flows of volcanoes makes it possible to create a magnetochronological scale for epochs of the same polarity.</p><p>According to the data of electron microprobe and thermomagnetic analyzes, the magnetic properties of samples from the lava flows of the Avachinsky volcano are mainly determined by titanic magnetite with a Curie temperature Tc = (540-580) °С. The study of magnetic mineral grains using electron and magnetic force microscopy showed the presence of decay structures in grains, indicating the high-temperature oxidation of titanomagnetite. Ferrimagnetic grains of samples from the Gorely and Tolbachik volcanoes are represented by titanomagnetite with a Curie temperature Tc = (200–300) °C. According to the hysteresis characteristics, the magnetic structure of the grains corresponds to a single-domain and pseudo-single-domain state. Thermal and magnetic cleanings showed the predominance of one component in the NRM. The geomagnetic field intensity was determined by the Thellier method in the Coe modification.</p><p>It was found that the paleointensity value H<sub>anc</sub> = 55±3 μT, determined from the NRM of samples of the 2012 eruption from the Tolbachik volcano, differs from the modern magnetic field in the area of this volcano by the IGRF-12 model by only 4% (Н<sub>IGRF</sub> = 53 μT). This indicates the reliability of our methodology for determining paleointensity from the most stable part of the NRM of igneous rocks.</p><p>A comparison of the coordinates of the paleomagnetic pole (N 66º±4º, E 266º±5º) and the virtual dipole magnetic moment of the Earth (VDM = 8.3±0.9*10<sup>22</sup> A*m<sup>2</sup>) with data on variations of the geomagnetic field over the past 10,000 years [Burlatskaya, 2007; McElhinny, 1982] allows us to conclude that the investigated lava flow belongs to the historical eruptions of 1827. The coordinates of the virtual geomagnetic pole (N 83º±3º, E 254º±21º) and the value of VDM = 8.0±0.3*10<sup>22</sup> A*m<sup>2</sup> determined from the samples belonging to the second lava flow of the Avachinsky volcano indicate that rocks are formed in the result of the eruption, which occurred 5-5.5 thousand years ago.</p><p>It was revealed that the magnitude (H<sub>anc</sub> =65±5μT) and the direction of paleointensity determined by the NRM of the samples from Gorely volcano significantly differ from the characteristics of the modern magnetic field. The assumption is made that the studied samples belong to the outpouring of lava, which occurred about 2.7 thousand years ago, during the "Sterno-Etrussia" geomagnetic excursion.</p><p> </p><p>This work was supported by the Russian Foundation for Basic Research, project 20-05-00573.</p>

Mount Etna and the 1971 eruption - Recent submarine pillow lavas in the Catania area, eastern Sicily

1973 ◽  
Vol 274 (1238) ◽  
pp. 153-162 ◽  
Keyword(s):  
Chemical Composition ◽  
Lava Flow ◽  
Electron Microprobe ◽  
Sea Water ◽  
Chemical Exchange ◽  
Mount Etna ◽  
Bulk Chemical Composition ◽  
Pillow Lavas ◽  
Bulk Chemical

A series of scuba dives were made during the summer of 1971 to examine the development and morphology of pillow lavas. A prehistoric and a fourteenth-century lava flow were sampled, and the subaerial to submarine transition observed and photographed. The structure of the pillows formed is believed to be dependent on rate of flow and general topography. The lack of hyaloclastite is discussed and related to the pillow formation. The development of palagonite rims to the pillows by the contact of sea water on sideromelane is described. Comparative analyses obtained by electron microprobe are presented. These results indicate a leaching of Si, Ca, Na and K in the altered portions of the pillows. The possible role of this chemical exchange to the bulk chemical composition of the oceans is discussed.

Comparing petrographic signatures of bioalteration in recent to Mesoarchean pillow lavas: Tracing subsurface life in oceanic igneous rocks

2007 ◽  
Vol 158 (3-4) ◽  
pp. 156-176 ◽  
Author(s):  
Harald Furnes ◽  
Neil R. Banerjee ◽  
Hubert Staudigel ◽  
Karlis Muehlenbachs ◽  
Nicola McLoughlin ◽  
...  
Keyword(s):  
Igneous Rocks ◽  
Pillow Lavas

Scanning and Transmission Microscopy of Nematocyst Batteries in Epitheliomuscular Cells of Hydra

1971 ◽  
Vol 29 ◽  
pp. 410-411 ◽  
Author(s):  
Jane A. Westfall ◽  
S. Yamataka ◽  
Paul D. Enos
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Osmium Tetroxide ◽  
External Surface ◽  
Three Dimensional ◽  
Surface Structures ◽  
Transmission Microscopy ◽  
Transmission Electron ◽  
Freeze Dried ◽  
Scanning Electron

Scanning electron microscopy (SEM) provides three dimensional details of external surface structures and supplements ultrastructural information provided by transmission electron microscopy (TEM). Animals composed of watery jellylike tissues such as hydras and other coelenterates have not been considered suitable for SEM studies because of the difficulty in preserving such organisms in a normal state. This study demonstrates 1) the successful use of SEM on such tissue, and 2) the unique arrangement of batteries of nematocysts within large epitheliomuscular cells on tentacles of Hydra littoralis.Whole specimens of Hydra were prepared for SEM (Figs. 1 and 2) by the fix, freeze-dry, coat technique of Small and Màrszalek. The specimens were fixed in osmium tetroxide and mercuric chloride, freeze-dried in vacuo on a prechilled 1 Kg brass block, and coated with gold-palladium. Tissues for TEM (Figs. 3 and 4) were fixed in glutaraldehyde followed by osmium tetroxide. Scanning micrographs were taken on a Cambridge Stereoscan Mark II A microscope at 10 KV and transmission micrographs were taken on an RCA EMU 3G microscope (Fig. 3) or on a Hitachi HU 11B microscope (Fig. 4).

High-resolution gold labeling

1993 ◽  
Vol 51 ◽  
pp. 330-331
Author(s):  
James F. Hainfeld ◽  
Frederic R. Furuya ◽  
Kyra Carbone ◽  
Martha Simon ◽  
Beth Lin ◽  
...  
Keyword(s):  
Dihydrofolate Reductase ◽  
Polypeptide Chain ◽  
External Surface ◽  
Gold Cluster ◽  
Macromolecular Complex ◽  
Gold Compound ◽  
Central Cavity ◽  
Chain Folding ◽  
E Coli ◽  
Chaperonin Groel

A recently developed 1.4 nm gold cluster has been found to be useful in labeling macromolecular sites to 1-3 nm resolution. The gold compound is organically derivatized to contain a monofunctional arm for covalent linking to biomolecules. This may be used to mark a specific site on a structure, or to first label a component and then reassemble a multicomponent macromolecular complex. Two examples are given here: the chaperonin groEL and ribosomes.Chaperonins are essential oligomeric complexes that mediate nascent polypeptide chain folding to produce active proteins. The E. coli chaperonin, groEL, has two stacked rings with a central hole ∽6 nm in diameter. The protein dihydrofolate reductase (DHFR) is a small protein that has been used in chain folding experiments, and serves as a model substrate for groEL. By labeling the DHFR with gold, its position with respect to the groEL complex can be followed. In particular, it was sought to determine if DHFR refolds on the external surface of the groEL complex, or whether it interacts in the central cavity.

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