CURIE TEMPERATURES OF THE Fe-Ti OXIDES OF BASALTS: IS IT POSSIBLE TO USE CURIE TEMPERATURES TO ASSESS THE SOURCE OR THE DEPTH OF ORIGIN OF THE Fe-Ti OXIDES AND RELATED BASALT MAGMAS?

Year, pages: 1996, 51 - 58

The Curie temperatures (T_C) of magnetic Fe-Ti oxides of basalts from 31 localities of Central and Southern Slovakia were measured. Titanomagnetites (TMs) are magnetic minerals in basalts with an ulvospinel content in the range from 3O to 70 %. The results of the laboratory tests proved a specific property of the TMs. They are able to change very easily their previous composition depending on either oxidative or reductive conditions. The original magnetic phases (of low T_C ≤ 300 °C) have been preserved in most of basalts. We suppose that the original — quasi homogeneous TMs were formed within a "dry magma". The basalts from 19 localities contain two magnetic phases. One of them has the T_C ≤ 300 °C (it is supposed to be the quasi-primary one), and the second — more oxidized phase (T_C ≤ 490–610 °C). There are basalts of eight localities containing only one, more oxidized phase (T_C ≤ 538–600 °C). Fe₃O₄, Fe₂O₃ and other Fe-Ti oxidized products are present in these basalts. These basalts are located near Kysihybel-Kalvaria, Savol, Sid, Konradovce, Blhovce, Blhovce Buda, Pohansky vrch (most of them are located in the NE part of the Cerova vrchovina Upland). The basalts with only one, more oxidized magnetic phase (T_C ≤ 538–600 °C) were formed probably from a "wet" (saturated by magmatic water) magma. I tried to assess the depths of the origin of basalt magmas, based on the T_C of the TMs of basalts, applying an idea of Petchersky et al. (1981). (The T_C of the quasi-primary phase — T_C ≤ 300 °C of the TMs oxides were used). The assessed depths are in the range 35–59 km in Central and Southern Slovakia. Huraiova & Konecny (1993) estimated that xenoliths were uplifted from depths of 35–85 km in Southern Slovakia. Fediuk (in Bucha & Blizkovsky et al. 1994) deduced from the evaluated results of thermodynamic calculations that balancing of lherzolite nodules took place at depths of about 50–80 km (i.e. under conditions of the uppermost mantle) — in the north of Bohemia, north of Moravia and south of Slovakia. The upper mantle/lower crust boundary lies ca. 27–29 km (Bezak et al. 1995) and melted asthenospheric material lies in the depth ca. 80–60 km, according to Sefara et al. (in press). The assessed depths of origin of basalt magmas based on the Curie temperatures of the TMs are compared with the data obtained by other authors. Geological phenomena and physico-chemical conditions have been considered in this contribution, to support or deny an idea for deriving the depth of origin of basalt magmas based on the Curie temperatures of the TMs of the basalts.

Orlicky, O. 1996. CURIE TEMPERATURES OF THE Fe-Ti OXIDES OF BASALTS: IS IT POSSIBLE TO USE CURIE TEMPERATURES TO ASSESS THE SOURCE OR THE DEPTH OF ORIGIN OF THE Fe-Ti OXIDES AND RELATED BASALT MAGMAS?. In Geologica Carpathica, vol. 47, no.1, pp. 51-58. 1335-0552.

Orlicky, O. (1996). CURIE TEMPERATURES OF THE Fe-Ti OXIDES OF BASALTS: IS IT POSSIBLE TO USE CURIE TEMPERATURES TO ASSESS THE SOURCE OR THE DEPTH OF ORIGIN OF THE Fe-Ti OXIDES AND RELATED BASALT MAGMAS?. Geologica Carpathica, 47(1), 51-58. 1335-0552.