A Multi-Disciplinary Study Evaluating Magma Emplacement Processes of the Oligocene Zákupy Diatreme (Czech Republic)
Abstract
The Oligocene Zákupy diatreme, Czech Republic is located at the SE termination of the NE-SW Eger Rift, near the intersect with the NW-SE dextral Labe-Odra fault system. The formation of maar-diatremes in continental rift systems remains an important but poorly understood subject as the roots of these systems are not often accessible. The Zákupy diatreme was quarried for building stone and the exposed high walls reveal up to 50m of the lower and upper diatreme facies that consist of proto-diatreme like intrusions injected into unconsolidated, lithic-rich, diatreme fill, that during assent, changed geometry, forming sills along bedding planes in water saturated, non-welded, lapilli tuffs. These sills are often highly fragmented with angular peperite horizons. Anisotropy of magnetic susceptibility data from 32 Zákupy sites yields primarily oblate magnetic fabrics. K1-K2 magnetic foliation planes and K1 lineation directions from paired margins of dikes indicate that there could be a structural control on magma flow in and out of the diatreme as dikes either follow a NE-SW fabric or a NW-SE fabric. Preliminary paleomagnetic data from 19 of 25 sites yield stable, single component magnetizations that decay linearly to the origin with less than 10% of the characteristic remenant magnetization remaining after treatment in 120mt applied field or thermal demagnetization up to 550° C. These data show scatter about the expected Miocene reverse polarity direction and statistically distinct directions between individual intrusions. We argue that these data reflect secular variation of the geomagnetic field and thus significant time between events. In addition, we report five new 40Ar/39Ar age determinations from dikes and sills that further constrain the age of emplacement. The results from this multidisciplinary study reveal that the Zákupy Diatreme is a complex, long-lived, volcanic system that displays characteristics that are better described by polygenetic emplacement model.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2016
- Bibcode:
- 2016AGUFM.V53C3130S
- Keywords:
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- 8419 Volcano monitoring;
- VOLCANOLOGYDE: 8434 Magma migration and fragmentation;
- VOLCANOLOGYDE: 8439 Physics and chemistry of magma bodies;
- VOLCANOLOGYDE: 8486 Field relationships;
- VOLCANOLOGY