DARWIN Digitale Dissertationen German Version Strich

FU Berlin
Digitale Dissertation

Detlef Kurth :
The North-Chilean Costal Cordillera at Taltal: Shear-Zones and Forearc-Sliver in the Jurassic and lower Cretaceous Magmatic Arc
Die Nordchilenische Küstenkordillere bei Taltal: Scherzonen und forearc-sliver im Jurassischen und Unterkretazischen magmatischen Bogen

 FU Logo

|Abstract| |Table of Contents| |More Information|

Abstract

The investigated area is located in the coastal cordillera of Northern Chile, south of the village named "Taltal" (25°24´50" S / 70°29´00" W). The geology comprises palaeozoic basement as well as rocks of the jurassic and lower cretaceous magmatic arc, the latter belonging to the Andine phase of the western South American orogenesis. The Atacama fault zone (AFZ) as a deeply plunging, orogen parallel strike slip zone divides the area into two different units. These units, classified in this thesis as crustal blocks, represent a distinct different geological evolution: The crustal block west of the AFZ - the Cifuncho block - exhibits a nearly complete stratigraphic record from Devonian and Permo-Carbon rocks, followed by Triassic and Jurassic rocks up to lower Cretaceous rocks. In the Pingo-Block the Triassic and Jurassic are lacking; the Cretaceous rocks following directly upon the paleozoic basement. The target of the presented investigations is the reconstruction of the evolution of the different crustal blocks (and subblocks) in space and time. The selected area exhibits structures of two magmatic arcs (Jurassic and lower Ceataceous) as well as the structures of both forearcs. Special interest was focussed both on movements, which were induced by subduction, and if the Cifuncho block due to its stratigraphic record could be defined as a terrane. As a result of the investigations it can be seen that the two magmatic arcs are affected by two intra-arc-faults. In the Jurassic magmatic arc one is represented by the "Las-Luces-fault"; in the lower Cretaceous magmatic arc it is represented by the AFZ. The tectonic evolution of the Cifuncho block correlates with the evolution of the Northern Chilean continental margin at that period. Furthermore it was worked out, that a movement of the Cifuncho block was possible only at that moment, that weakening of the lithosphere by intense arc magmatism was so intense, that a decoupling of upper and lower crust was possible. The following movement of the Cifuncho block was directed southwards, due to the subduction parameters at that time. Therefore the AFZ represents a complex system of elder strike-slip-faults and an intra arc fault leading into a sutur zone between the South american continental margin (the "Pingo-block) and a forearc-sliver, the Cifuncho-block. The results of this thesis prove the presence of an active magmatic arc as a weak zone of the continental crust, in which the subduction induced deformation is focussed.

Table of Contents

Download the whole PhDthesis as a zip-tar file or as zip-File

For download in PDF format click the chapter title

1. TITELBLATT
1. EINFÜHRUNG UND ARBEITSANSATZ 1
1.1. VORWORT 1
1.2. GEOLOGISCHER RAHMEN 1
1.3. ARBEITSANSATZ 8
1.4. ARBEITSGRUNDLAGEN UND METHODIK 12
1.5. GEOGRAPHIE DES ARBEITSGEBIETES 13
1.5.1. Taltal / Infrastruktur 13
1.5.2. Morphologie 15
1.5.3. Klima 15
1.5.4. Tiere und Pflanzen 16
2. GEOLOGIE 17
2.1. SEDIMENTÄRE UND VULKANISCHE FORMATIONEN 17
2.1.1. Formación Las Tórtolas (Devon - Karbon) 17
2.1.2. Formación Cifuncho (Obertrias) 21
2.1.3. Formación Pan de Azucar (Hettangium - Sinemurium) 28
2.1.4. Formación Posada de los Hidalgo (Hettangium - Sinemurium) 32
2.1.5. Formación La Negra (Toarcium - Bathonium) 34
2.1.6. Formación Aeropuerto (Unterkreide) 37
2.1.7. Gravas de Atacama (Oligozän - Miozän) 44
2.1.8. Quartäre Ablagerungen 44
2.2. PLUTONISCHE UND SUBVULKANISCHE INTRUSIONEN 46
2.2.1. Grupo Plutonico Cifuncho (Permo-Karbon) 46
2.2.2. Grupo Plutonico Matancilla (Jura) - Überblick 47
2.2.3. Grupo Plutonico Matancilla: Altersverteilung im Arbeitsgebiet 50
2.2.4. Grupo Plutonico Cerro del Pingo (Unterkreide) 51
2.3. GÄNGE UND STÖCKE 53
2.3.1. Jurassische Lagergänge und Stöcke in der Formación Cifuncho 53
2.3.2. Jurassische dykes 55
3. STRUKTUREN 56
3.1. DIE ATACAMA-STÖRUNGSZONE 58
3.1.1. Verlauf der Atacama-Störung und Störungsgesteine 58
3.1.2. Schersinnindikatoren entlang der Atacama-Störungszone 62
3.1.3. Alter der Bewegung an der Atacama-Störungszone 62
3.1.4. Druckindikatoren an Intrusivgesteinen im Bereich der Atacama-Störungszone 66
3.2. DAS LAS-LUCES-LINEAMENT 67
3.3. N- BIS NW-STREICHENDE STÖRUNGEN AN TEILBLOCKGRENZEN 71
3.3.1. Störungssystem in der Quebrada Buena Esperanza 71
3.3.2. Störungssystem in der Quebrada del Gritón 72
3.3.3. Aguada Jacinto Diaz 73
3.4. NE-STREICHENDE STÖRUNGEN 73
3.4.1. NE-Versatz in der Quebrada Fuente del Arriero 73
3.4.2. NE-Lineament entlang der Quebrada Cifuncho 76
3.5. TALTAL-STÖRUNG 78
3.6. STRUKTUR-INVENTAR AUSGEWÄHLTER GEBIETE 80
3.6.1. Strukturen in den Cerros de Gritón und der Quebrada del Gritón 82
3.6.2. Strukturen im Bereich der Quebrada Buena Esperanza 86
3.6.3. Strukturen nördlich der Quebrada Tigrillo 91
3.6.4. Tektonik in den kretazischen Serien der Mina Unión 91
4. ENTWICKLUNG 92
4.1. PRÄANDINE ENTWICKLUNG 92
4.1.1. Paläozoikum im Cifuncho- und Pingo-Block 92
4.1.2. Trias im Cifuncho-Block - Erste andinotype Entwicklungen 94
4.2. ANDINE ENTWICKLUNG - DER JURASSISCHE MAGMATISCHE BOGEN 99
4.2.1. Das Initialstadium (208-195 Ma) 102
4.2.2. Aktiver jurassischer magmatischer Bogen (195-160 Ma) 104
4.2.3. Sinistrale Transtension (160-150 Ma) 109
4.2.4. Transtension und Extension (150-140 Ma) 113
4.2.5. Der unterkretazische magmatische Bogen 116
4.2.6. Die Atacama-Störungszone (148-123 Ma) 117
4.2.7. Zusammenfassung 122
4.3. DAS GEBIET ALS FOREARC 124
4.3.1. NW-streichende Lineamente und Störungen 125
4.3.2. NE-streichende Lineamente und Störungen 125
5. DISKUSSION 128
5.1. TERRANE UND FOREARC-SLIVER - EIN VERGLEICH 128
6. LITERATURVERZEICHNIS 132
7. ANHANG 140

More Information:

Online available: http://www.diss.fu-berlin.de/2002/55/indexe.html
Language of PhDThesis: german
Keywords: Chile, Costal Cordillera, Strike Slip Zones, Atacama Fault Zone, Magmatic Arc, Taltal
DNB-Sachgruppe: 31 Geowissenschaften
Date of disputation: 20-Apr-2000
PhDThesis from: Fachbereich Geowissenschaften, Freie Universität Berlin
First Referee: Prof. Dr. Klaus-Joachim Reutter
Second Referee: Priv.-Doz. Dr. Ekkehard Scheuber
Contact (Author): DetKurth@aol.com
Contact (Advisor): scheuber@geophysik-fu-berlin.de
Date created:14-Apr-2002
Date available:15-Apr-2002

 

|| DARWIN|| Digitale Dissertationen || Dissertation|| German Version|| FU Berlin|| Seitenanfang ||

Mail-Icon Fragen und Kommentare an:
darwin@inf.fu-berlin.de

© Freie Universität Berlin 1999