The endothermic decomposition of thaumasite from Mothae which has been investigated by DTA and TG... more The endothermic decomposition of thaumasite from Mothae which has been investigated by DTA and TG shows a peak temperature of 138–203°, and reaction orders of 0.45–1.00, depending on the heating rate employed. The activation energy of the reaction was found to be about 19 kcal/mole; the enthalpy is 246 cal/g.
The Alno igneous complex intruded local migmatites and granite country-rocks of Svecofennian age ... more The Alno igneous complex intruded local migmatites and granite country-rocks of Svecofennian age at ~580 Ma and produced a suite of early alkaline silicate intrusives (e.g., ijolites, nepheline syenites) and dykes (e.g., trachytes, phonolites) and later a suite of carbonatite sheet intrusions for which Alno is widely known. The Alno igneous complex displays an older and deformed northern ring complex and the main “southern” ring complex. An explosive carbonatite vent with melilitite lapilli is apparently a late event, as are kimberlitic alnoite dykes. The latter seem not to be diamantiferous.
The Alno ring complex is one of the best known carbonatite complexes in the world, with ca. 100 s... more The Alno ring complex is one of the best known carbonatite complexes in the world, with ca. 100 scientific articles published since 1895. The Alno complex hosts a suite of alkaline silicate and car ...
Der Glauberg und der Altkonig sind zwei befestigte Hohensiedlungen in Hessen, die etwa gleichzeit... more Der Glauberg und der Altkonig sind zwei befestigte Hohensiedlungen in Hessen, die etwa gleichzeitig am Ende der spaten Hallstatt- und in der fruhen Latenezeit besiedelt waren. Beide Anlagen wurden durch Pfostenschlitzmauern vom Typ Altkonig-Preist geschutzt, die in einem Schadensfeuer zugrunde gingen. Dabei kam es zum Phanomen der Gesteinsschmelze, das am Glauberg in mehreren Schnitten im Mauerkern nachgewiesen werden konnte, am Altkonig im Bereich des Tors des inneren Ringwalls. Handelt es sich bei den analysierten Proben vom Glauberg um Gesteinsschmelzen, die beim Brand der spathallstattzeitlichen Mauer I in deren Kern entstanden sind, so sind die Proben vom Altkonig das Resultat der Herstellung und Bearbeitung von Eisen, deren Datierung freilich einstweilen unsicher bleibt.
While attempting to date material from the vitrified ramparts of various hill-forts in central an... more While attempting to date material from the vitrified ramparts of various hill-forts in central and western Europe by thermoluminescence (TL) methods, obviously erroneous results appeared. Searching for possible reasons, an investigation into the upper temperature limit of TL-dating was started. It is well known that insufficient heating causes far too old erroneous TL-ages. Less well known and yet unexplored is the temperature region where vitrification commences. From a hill-fort near Uppsala, samples were taken along a trench through the vitrified rampart. Firing temperatures were determined for each sample by petrographic methods within ±50°C, and TL-measurements were carried out. The results show that the ages determined become successively younger with increasing firing temperatures, for samples heated to temperatures exceeding 900°C. The younger the apparent age, the higher the glass content of the sample. Although most of our data are from vitrified ramparts – somewhat exotic...
The model of dyke emplacement proposed by v. Eckermann could not be confirmed by the present stud... more The model of dyke emplacement proposed by v. Eckermann could not be confirmed by the present study. A new model is suggested, involving up-doming of the wall-rock due to the intrusion of magma (accompanied by the formation of radial dykes and two sets of cone sheets), followed by subsidence (formation of sövite ring dykes and two other sets of cone sheets).
The endothermic decomposition of thaumasite from Mothae which has been investigated by DTA and TG... more The endothermic decomposition of thaumasite from Mothae which has been investigated by DTA and TG shows a peak temperature of 138–203°, and reaction orders of 0.45–1.00, depending on the heating rate employed. The activation energy of the reaction was found to be about 19 kcal/mole; the enthalpy is 246 cal/g.
The Alno igneous complex intruded local migmatites and granite country-rocks of Svecofennian age ... more The Alno igneous complex intruded local migmatites and granite country-rocks of Svecofennian age at ~580 Ma and produced a suite of early alkaline silicate intrusives (e.g., ijolites, nepheline syenites) and dykes (e.g., trachytes, phonolites) and later a suite of carbonatite sheet intrusions for which Alno is widely known. The Alno igneous complex displays an older and deformed northern ring complex and the main “southern” ring complex. An explosive carbonatite vent with melilitite lapilli is apparently a late event, as are kimberlitic alnoite dykes. The latter seem not to be diamantiferous.
The Alno ring complex is one of the best known carbonatite complexes in the world, with ca. 100 s... more The Alno ring complex is one of the best known carbonatite complexes in the world, with ca. 100 scientific articles published since 1895. The Alno complex hosts a suite of alkaline silicate and car ...
Der Glauberg und der Altkonig sind zwei befestigte Hohensiedlungen in Hessen, die etwa gleichzeit... more Der Glauberg und der Altkonig sind zwei befestigte Hohensiedlungen in Hessen, die etwa gleichzeitig am Ende der spaten Hallstatt- und in der fruhen Latenezeit besiedelt waren. Beide Anlagen wurden durch Pfostenschlitzmauern vom Typ Altkonig-Preist geschutzt, die in einem Schadensfeuer zugrunde gingen. Dabei kam es zum Phanomen der Gesteinsschmelze, das am Glauberg in mehreren Schnitten im Mauerkern nachgewiesen werden konnte, am Altkonig im Bereich des Tors des inneren Ringwalls. Handelt es sich bei den analysierten Proben vom Glauberg um Gesteinsschmelzen, die beim Brand der spathallstattzeitlichen Mauer I in deren Kern entstanden sind, so sind die Proben vom Altkonig das Resultat der Herstellung und Bearbeitung von Eisen, deren Datierung freilich einstweilen unsicher bleibt.
While attempting to date material from the vitrified ramparts of various hill-forts in central an... more While attempting to date material from the vitrified ramparts of various hill-forts in central and western Europe by thermoluminescence (TL) methods, obviously erroneous results appeared. Searching for possible reasons, an investigation into the upper temperature limit of TL-dating was started. It is well known that insufficient heating causes far too old erroneous TL-ages. Less well known and yet unexplored is the temperature region where vitrification commences. From a hill-fort near Uppsala, samples were taken along a trench through the vitrified rampart. Firing temperatures were determined for each sample by petrographic methods within ±50°C, and TL-measurements were carried out. The results show that the ages determined become successively younger with increasing firing temperatures, for samples heated to temperatures exceeding 900°C. The younger the apparent age, the higher the glass content of the sample. Although most of our data are from vitrified ramparts – somewhat exotic...
The model of dyke emplacement proposed by v. Eckermann could not be confirmed by the present stud... more The model of dyke emplacement proposed by v. Eckermann could not be confirmed by the present study. A new model is suggested, involving up-doming of the wall-rock due to the intrusion of magma (accompanied by the formation of radial dykes and two sets of cone sheets), followed by subsidence (formation of sövite ring dykes and two other sets of cone sheets).
Uploads
Papers by Peter Kresten