Die Erzparagenese des Katzenbuckels im Odenwald

Frenzel, Gerhard

doi:10.1007/bf01129196

Cited by 8 publications

(4 citation statements)

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“…Representatives of the to series, or the or- In some alkali-gabbros and their variants (shonkinites), an to phase co-exists with an a phase as discrete independent grains in the alkali-feldspar-rich groundmass. Frenzel [1953] has described such an occurrence of an to phase in the Odenwald shonkinite, and White [1965] presented the analyses of a co-existing to phase and an a phase found as independent needlelike grains in the groundmass of an Hawaiian alkali gabbro. In both rock types an unusual yellow pyroxene rich in ferric iron is found as phenoerysts.…”

Section: Pseudobr00kite---the To Seriesmentioning

confidence: 99%

“…One conclusion from the data on the •, series may be of some interest in estimating the temperature at which subsequent oxidation may occur. At temperatures above 600øC, (the breakdown temperature of pseudobrookitc [Lindsley, 1965]), the oxidation of an a phase would produce lamellas of an • phase parallel to the rhombohedral planes (10-11) [Frenzel, 1953, Figure 13], but temperatures below 600øC the oxidation of an a phase would result in the exsolution of rutile. It is, therefore, possible by microscopic examination to determine whether the subsequent oxidation (with an assumed absence of metastability) occurred above or below 600øC; the subsequent low-temperature breakdown of the • phase lamellas to an a phase and rutile does not apparently destroy the critical textural evidence.…”

Section: All Show a Small Excess Of Fe•08 Over That Necessary To Combmentioning

confidence: 99%

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Iron-titanium oxides and oxygen fugacities in volcanic rocks

Carmichael¹,

Nicholls²

1967

J. Geophys. Res.

238

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It is shown that in silicate liquids the ferric‐ferrous equilibrium is controlled by temperature, oxygen fugacity, and the composition of the liquid, particularly its alkali content. Thus, if the iron‐titanium oxide minerals that precipitate from a silicate liquid reflect the ferric‐ferrous equilibrium, the oxygen geobarometer of Buddington and Lindsley will have to be calibrated, especially for such volcanics as phonolites and pantellerites, which are rich in alkali. Estimates of oxygen fugacities for average basalts show that they probably crystallize through a more restricted range of oxygen fugacity than acid volcanics. Alkali gabbros with pseudobrookite, for which analytical data is given, have crystallized at relatively high oxygen fugacities, as have the volcanics (and kimberlites) that contain perovskite and an oxide phase. The calculated oxygen fugacities of sphene‐bearing acid rocks approximate the values derived from the coexisting oxide equilibration data and indicate higher values than pyroxeneor olivine‐bearing acid volcanics. The data on oxygen fugacity and crystallization temperature for basaltic liquids have been used to predict the composition of their coexisting oxide minerals; accordingly, basalts with Curie temperatures significantly in excess of approximately 200°C are considered to have been subsequently oxidized. Unless the temperature at which this later oxidation occurs is known, thermoremanent magnetization (TRM) cannot be demonstrated to exist in basalts. TRM can only be mineralogically demonstrated in the basaltic rocks that contain an orthorhombic oxide phase or its breakdown products.

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Section: Pseudobr00kite---the To Seriesmentioning

confidence: 99%

Section: All Show a Small Excess Of Fe•08 Over That Necessary To Combmentioning

confidence: 99%

Iron-titanium oxides and oxygen fugacities in volcanic rocks

Carmichael¹,

Nicholls²

1967

J. Geophys. Res.

238

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“…3 TAS diagram for the investigated rocks in the southern CEVP. Thirty-four new analyses performed according to the XRF method reported in Braunger et al (2018) were supplemented by literature data from Dunworth and Wilson (1998), Frenzel (1975), Hegner et al (1995), Hurrle (1976), Keller et al (1990), Krause and Weiskirchner (1981), Neumann et al (1992), Staesche (1995), Stähle and Koch (2003), and Stellrecht and Emmermann (1970). All data have been renormalized to a volatile-free composition.…”

Section: Geological Settingmentioning

confidence: 99%

Two distinct age groups of melilitites, foidites, and basanites from the southern Central European Volcanic Province reflect lithospheric heterogeneity

Binder

Marks

Gerdes

et al. 2022

Int J Earth Sci (Geol Rundsch)

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Petrographic observations and in situ U–Pb ages of melilitites, foidites, basanites, phonolites, and trachytes from the southern part of the Central European Volcanic Province (CEVP) and related plutonic inclusions therein reveal two distinct age groups separated by a gap of ~ 20 Myr. A late Cretaceous to early Eocene group (~ 73–47 Ma; Taunus, Lower Main plain, Odenwald and Kraichgau area, Bonndorfer Graben and Freiburger Bucht area, Vosges and Pfälzerwald) is characterized by nephelinites and basanites mostly devoid of melilite and perovskite, and by rare haüynites, and trachytes. In contrast, a late Oligocene to late Miocene group (~ 27–9 Ma; Lorraine, southern Upper Rhine Graben, Urach, Hegau area) is dominated by melilitites, melilite-bearing nephelinites (both carrying perovskite), and phonolites. Both magmatic episodes are related to domal topographic uplift, erosion, and formation of major angular unconformities in the Upper Rhine Graben, suggesting an association with dynamic topography interrupted by phases of subsidence (or abatements of uplift). The investigated rocks in the southern CEVP (south of a line Eifel–Vogelsberg–Rhön–Heldburg), except for the Kaiserstuhl volcanic complex, mostly comprise small and isolated occurrences or monogenetic volcanic fields, whereas the northern CEVP is dominated by large volcanic complexes and dyke swarms, which are mostly SiO2-saturated to weakly SiO2-undersaturated. In the northern CEVP, evidence of spatially varying but recurrent volcanic activity exists since the Eocene, lacking the distinct 20 Myr gap as documented from the southern CEVP. While the temporal and spatial distribution of volcanism are a result of the Cretaceous to Miocene tectonic evolution in Central Europe, further studies are needed to explain the petrographic differences between the two age groups in the south.

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“…Some sparse volcanic activity occurred already in the Late Cretaceous (c. 70-68 Ma) with presumed genetic relationships to the URG and volcanoes aligned along the eastern shoulder of the northern URG from the Kraichgau (K) in the south to the eastern Taunus and western Spessart Mountains in the north (e.g. Anderle 1974;Frenzel 1955, Frenzel 1975Lippolt et al 1975;Schweizer and Kraatz 1982;Lorenz et al 2010). This Early Tertiary volcanism shows several main phases of activity with a climax in the Middle Eocene (49-47 Ma; e.g.…”

Section: Introductionmentioning

confidence: 99%