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André Steenken:

The emplacement of the Rieserferner Pluton and its relation to the DAV-Line as well as to the kinematic and thermal history of the Austroalpine basement (Eastern Alps, Tyrol)

2002. 120 pages, 52 figures, 5 tables, 14 plates, 16x24cm, 350 g
Language: English

(Geotectonic Research, Volume 94)

ISBN 978-3-510-50060-4, paperback, price: 69.00 €

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Keywords

AlpenRieserferner-PlutonAnisotropieGeochronologiethermische ModellierungAlpsRieserferner Plutonanisotropygeochronologythermal modelling

Contents

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As a consequence of this study fabric orientation within the Rieserferner Pluton is regarded to approximate its orientation during solidification of the intruding magma. Fabric orientation suggests magma accommodation in a westward opening pull-apart structure between the DAV-Line (Defereggen-Antholz-Vals-Line) in the south and the mylonites bordering the pluton to the north. From thermo-geochronological dating it is evident that the "tail" of the pluton represents the highest exposed part of the pluton.

Inhaltsbeschreibung top ↑

Aus den Ergebnissen dieser Arbeit wird geschlossen, daß die Orientierung der Gefüge des Rieserferner-Plutons annähernd der bei der Verfestigung des Magmas entspricht. Die Gefügeorientierung deutet darauf hin, daß das Magma in einer sich nach Westen öffnenden Pull-Apart-Struktur zwischen der DAV-Linie (Defereggen-Antholz-Vals-Linie) und den Myloniten am Nordrand des Plutons aufgenommen wurde. Thermogeochronologische Datierungen belegen, daß der Östliche Rieserferner den höchsten Teil des Plutons repräsentiert.

Contents top ↑

Abstract
Kurzfassung
1. Introduction 7
1.1. Granite tectonics 8
1.2. Cooling vs. exhumation, methodical considerations 10
1.3. Geographical setting 11
1.4. Geological setting 12
2. Geology 12
2.1. The Periadriatic Lineament and the Defereggen-Antholz-Vals-Line 12
2.2. The Rieserferner Pluton 15
3. Field observation 17
3.1. Petrologic sub-units 18
3.2. MacroscopiCfabric 20
3.2.1. Central and southern domain 21
3.2.2. Northernmarginaldomain 21
3.3. Enclaves 23
3.3.1. Country rock xenoliths 23
3.3.2. Microgranular enclaves 23
3.4. Late stage intrusions 25
3.5. Deformation in the country rocks 29
3.5.1. Syn-intrusive mylonites 31
4. Microfabric 33
4.1. Magmatic to sub-magmatic deformation 33
4.2. High temperature solid-state deformation 34
4.3. Low temperature solid-state deformation 39
4.4. Results 39
5. Anisotropy of magnetic susceptibility (AMS) 43
5.1. Methods 43
5.2. Sample preparation and measurement 46
5.3. Significance of magnetic fabrics 47
5.3.1. Biotite texture 47
5.3.2. Curie balance 48
5.3.3. HFA-analysis 48
5.4. Discussion of the magnetic parameters 50
5.5. Directional data 52
5.6. Results 53
6. Bulk susceptibility versus petrography 56
6.1. Calculating the bulk susceptibility 57
7. Age constraints 61
7.1. Data acquisition and experimental procedure 62
7.1.1. K/Ar-dating 62
7.1.2. Fission-track dating 64
7.1.2.1. Theoretical background of fission-track dating 66
7.1.3. Closure temperatures 67
7.1.4. Significance of Rb/Sr- and K/Ar-muscovite cooling ages 68
7.1.5. Regional distribution of Rb/Sr- and K/Ar-biotite cooling ages 70
7.1.6. Regional variation in FT-ages 72
7.2. Thermal history and constraints on the exhumation rates 78
7.3. Results 83
8. Exhumation versus post-intrusive cooling of the Rieserferner Pluton:
numerical modelling 84
8.1. Basic assumptions 86
8.1.1. Melt temperature 88
8.2. The thermal anomaly of the Rieserferner Pluton: results of modelling 89
9. Discussion and conclusion 94
9.1. Implications for the emplacement of the Rieserferner Pluton 94
Danksagung 99
References 100
Appendices
I. AMSdata 109
II. Apatite radial plots and track length distribution 113
III. Zircon radial plots 119