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| Titel: |
Cooling rate effects on the magnetization of volcanic rocks: Some implications for paleointensity determination |
| Auteur: |
Juan Morales Avto Goguitchaichvili Jaime Urrutia-Fucugauchi |
| Verschenen in: |
Geofísica internacional |
| Paginering: | Jaargang 45 (2006) nr. 2 pagina's 141-146 |
| Jaar: |
2006 |
| Inhoud: |
Effects of variation of cooling rate in the acquisition of thermoremanent magnetization (TRM) are analyzed on a suite of volcanic rocks. We use a three-step cooling rate experimental procedure applied at three distinct temperatures of TRM acquisition. Sixteen selected, thermally stable samples from Late Quaternary lava flows were given a pTRM (300°C) at a slow cooling rate. The acquired intensities were measured at room temperature. A second pTRM was applied to the same specimens using a fast cooling rate, and the acquired intensities were measured at room temperature. Finally a third pTRM was induced as in the first step, using a slow cooling rate. The procedure was repeated to create pTRM’s at higher temperatures of 450° and 550°C. Corresponding percent variations between magnetization intensities acquired at slow-fast and at slow-slow cooling rates were calculated to investigate the influence of cooling rate on TRM intensity acquisition, and on TRM acquisition capacity. We observe values as high as 300 % in the former case (300 °C). Intensity of the ancient geomagnetic field obtained from volcanic rocks could be overestimated by at least 15% due to a variation in cooling rate normally employed in the laboratory, as compared to slower rates found in nature. |
| Uitgever: |
Universidad Nacional Autónoma de México, Instituto de Geofísica (provided by DOAJ) |
| Bronbestand: |
Elektronische Wetenschappelijke Tijdschriften |
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