Zur Morphologie des Taramellits

Zusammenfassung Taramellit kommt im westlichen Nordamerika an mindestens acht Fundstellen vor, wo er bis jetzt wenig beachtet wurde. Die Taramellite dieser Fundstellen sind alle sehr Ti-reich. Bisher wurde Taramellit nach dem ersten Vorkommen, Candoglia in Italien, meist als faserig beschrieben. Die Ti-reichen Taramellite in Nordamerika, besonders die in California, welche mit Sanbornit und Gillespit vorkommen, erscheinen aber als gut ausgebildete Einkristalle. Es wurden viele solche Kristalle goniometrisch gemessen. Obgleich etwa dreißig Formen verzeichnet wurden, ist der Habitus der orthorhombischen Kristalle meist durch das Vorherrschen der Pinakoide und einiger {hk0} und {0kl} Prismen bedingt. Am häufigsten ist der tafelige habitus nach {100}.

---

On the morphology of taramellite

Summary Taramellite is known from at least eight localities in western North America but has received little notice. The taramellite at all of these localities is especially Ti-rich. Hitherto taramellite has mostly been described as fibrous after its habit at the type locality, Candoglia, Italy. The Ti-rich taramellites of North America, especially those found with sanbornite and gillespite in California, occur as well-developed single crystals. Many such crystals were measured goniometrically. Though about thirty forms were recorded, the habit of the orthorhombic crystals is mostly determined by the pinacoids and a few {hk0} and {0kl} prisms. A tabular habit with {100} dominant is most common.

---

---

Mit 3 Abbildungen

---

herrn Prof. Dr.H. Meizner zum 70. Geburtstag gewidmet.     

Some thoughts on the pre-Alpine metamorphic history of the austridic basement of the Eastern Alps

Summary In several places of the old crystalline basement of the Eastern Alps a classification of the pre-Alpine metamorphic effects into an older, high-to intermediate-pressure metamorphism (eclogites, kyanite) and a younger, lower-pressure one (and±ky±cord) is recognizable. Some local geological situations allow a sharp chronological distinction to be made between these two events; and the available radiometric age values demonstrate the Caledonian age (500 m.y.) of the older metamorphism and the Hercynian age (320 m.y.) of the younger one. Elements exist showing that the Caledonian metamorphism, belongs to a complex cycle of geological processes which took place substantially during the Ordivician age (?) and has all the ingredients of the orogenic cycles. This evolutional picture represents a possible model for the whole of the Eastern Alps.

---

Überlegungen zur Entwicklung der voralpidischen Metamorphose im Ostalpin

Zusammenfassung An mehreren Stellen im altkristallinen Grundebirge der Ostalpen ist eine Gliederung der voralpidischen metamorphen Ereignisse in eine ältere Metamorphose, die einer hoch-bis mitteldruckbetonten Faziesserie (Eklogite, Disthen) angehört und eine jüngere weniger druckbetonte Metamorphose (Andalusit±Disthen±Cordierit) erkennbar. Einzelne lokale geologische Situationen erlauben eine scharfe chronologische Trennung dieser zwei Ereignisse; das Caledonische Alter ( 500m.y.) der älteren und das Hercynische Alter ( 320 m.y.) der jüngeren Metamorphose wird durch radiometrische Altersdaten demonstriert. Es gibt Hinweise, daß die Caledonische Metamorphose zu einem komplexen geologischen Ereignis mit allen Kennzeichen eines orogenen Zyklusses gehört, das im wesentlichen während des Ordoviziums stattgefunden hat. Diese genetischen Vorstellungen scheinen als mögliches Modell für die gesamten Ostalpen annehmbar.

---

---

With 3 Figures     

Einige Probleme des Variszikums von Neo-Europa

The Periadriatic Lineament and its possible extension, the Balatonline, on the one hand and the Balcan-Dinaric Lineament and its continuation (?) the Zagreb-line, on the other hand, separate an outer-region, characterized by clastic, terrestrical Upper Carboniferous and Permian strata, from a marine Inner-region. This Inner-region includes the Southern Alps, the Dinarides, and the ?Igoler“-trough. The aforementioned lineaments were not evident during the Lower Paleozoic, whereas in the Upper Paleozoic (after the Variscan orogenese) a clear separation of the two areas can be seen. As a consequence of the overlapping of the marine sequence into the regions north of the Periadriatic lineaments during the Triassic, the contrast between outer- and inner-regions are agained wiped out. For a full understanding of these facts, significant details are still missing. Above all it is important to find a solution for several still unanswered questions: how far the outer region is still a part of the paleomagnetic “Stabile Europe”; how far the metamorphic development within the region of the Balcan Peninsula, the Pannonic Basin and the Karpates can be compared with the ideas (supported by isotopic-geological dates) of the metamorphic development on both sides of the Insubric line and also how far the Dinaric Ophiolite zones are remains of a Paleothetys. Only when these questions are answered will it be possible to insert the Variscan area into the discussion of plate-tectonics within the Neo-European region.     

Pulsation of tectonic phenomena and tectonophysical mechanisms

At present, it is believed that the main tectonic phenomena result from progressive displacements of a small number of rigid plates which form the crust of the Earth. If the plates separate, a rift (of oceanic type) will open; and, if they approach, compression will shorten the crust and form eventually a mountain chain. Both rifting and compression produce earthquakes at the plate borders, and the seismic activity must depict the rate of movement of the plates. There is some indication that this seismic activity occurs in pulses with a period of about 11 years, rifting probably alternating with compression. For long lasting monotonic plate movements, thermal convection and radioactive undations could be adequate causes; but, for these short-period alternating phenomena, gravitational pulsations are considered the best available mechanism. Gravitational pulsations seem to be a necessary consequence of General Relativity, when applied to a convenient cosmological model.     

Paläogeographische Entwicklungen an mobilen Schollengrenzen im Westhindukusch (Bande Amir,Zentralafghanistan)

In the region of Bande Amir, located on the southern rim of the Tadschik basin, the Mesozoic section starts with detrital and conglomeratic limestones. These marine deposits of Upper Cretaceous age (Cenomanian-Turonian) disconformably cover a truncated complex of Upper Paleozoic rocks (Permian). After an interval of neritic sedimentation (Santonian, Campanian) the Upper Cretaceous sea (Maastrichtian) regressed from the Central Afghanian High. In the Hindukusch mountains the regression is related to crustal movements and regional uplifts, which hinged on the Herat lineament. Intermontane basins, developed on this mobile zone during mid-Tertiary time, gathered continental debris (Neogene conglomerates; Zohak-Formation) and led to the deposition of lacustrine sediments (Ghulghola-Formation). Orogenetic movements along the colliding edges of crustal blocks were rejuvenated in Plio-Pleistocene time, shifting the focus of deposition to the northwest. The basin was finally captured by the Amu Darja drainage system, leading to the development of canyon-like incisions. During warm periods of the Quaternary, fluviatile erosion in Bande Amir was interrupted at least four times by the retention of water behind large dams of travertine.     

Seismische Anisotropie des oberen Erdmantels und Intraplatten-Tektonik

Specially planned explosion seismic measurements in the oceans provided conclusive evidence that the velocity of P_n-waves depends on the azimuths of the direction of propagation through the upper mantle. The orientation of this azimuthal anisotropy suggests a close connection with the generation of the oceanic lithosphere: in the Pacific the maximum and minimum velocities are measured in a perpendicular and parallel direction to the axis of the oceanic ridges respectively. The observed anisotropy is so strong that a number of models for the generation of anisotropy can be discarded. The most likely cause is a preferred orientation of minerals. The generation of the anisotropy can be simulated in the laboratory under P-T-conditions of the upper mantle. The influence of the rate of deformation can be studied as well. A recent analysis of explosion seismic data in Southern Germany suggests that the continental upper mantle possesses also a velocity anisotropy dependent on azimuth.     

Pétrographie des „Permoskyth“ der Jaggl-Plawen-Einheit (Südtirol) und Diskussion der Detritusherkunft mit Hilfe von Kathoden-Lumineszenz-Untersuchungen

The Permo-Scythian deposits E of Lake Reschen (North-Italy) are composed of a sequence of terrestrial sediments in Verrucanofacies and of a series of detrital carbonate and lagoonal-evaporitic rocks (“Wechselschichten”) overlaid by Anisian fossiliferous dolomites. Examinations by cathodo-luminescence give reference to the source area of the detrius and to the diagenesis of the sediments. Further statements can be made by X-ray (triclinity of K-feldspars; inclusions in authigenic minerals) and chemical examinations (composition of dolomites). The detritus of the slightly metamorphic rocks, indicated by the crystallinity of illite, does not originate from the underlying “Plawenkristallin” and from the adjacent “ötztalkristallin”, respectively, but by 70% from a porphyritic source area that is supposed to be located in the region of Lugano.