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Heinrich Bahlburg:

The Ordovician basin in the Puna of NW Argentina and N Chile: Geodynamic evolution from back-arc to foreland basin

1990. 107 pages, 55 figures, 5 tables, 16x24cm, 290 g
Language: English

(Geotectonic Research, Volume 75)

ISBN 978-3-510-50041-3, paperback, price: 45.00 €

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Keywords

forelandOrdovicianArgentinavolcaniclavarockLandspitzeOrdoviziumArgentinienvulkanischLavaFels

Contents

Content Description top ↑

In the southern Central Andes of northwestern Argentina and northern Chile, Ordovician sedimentary rocks occur in the Argentinian Cordillera Oriental mainly in shelf facies, in the westwardly adjacent Puna highlands predominantly in deep marine turbidite facies. Measuring of detailled sedimentological sections and their sequence stratigraphic interpretation together with finds of graptolites in many new localities led to a more detailled subdivision of the c. 7000 m thick basin fill and an analysis of the Ordovician Puna basin and its geodynamic evolution.

Descriptión del Contenido top ↑

En la parte sur de los Andes Centrales, en el sector noroeste de Argentina y norte de Chile, existen afloramientos de clastitas del Ordovícico, en el área de la Cordillera Oriental de Argentina en facies de plataforma y, hacia el oeste en la Puna, a lo contrario predominantemente en facies marinas profundas de turbiditas. Perfiles sedimentológicos levantados en estas facies, en la Puna septentrional, con gran cantidad de nueva fauna de graptolides, permiten una divisíon estratigráfica más detallada de la serie sedimentaria de aproximadamente 7000 m de potencia y una analisis de la evolucíon geodinamica de la cuenca Ordovícica de la Puna.

Inhaltsbeschreibung top ↑

In den südlichen Zentralanden von Nordwestargentinien und Nordchile kommen Klastite ordovizischen Alters im Bereich der argentinischen Ostkordillere in Schelf-Fazies, im westlich angrenzenden Puna-Hochland hingegen überwiegend in tief mariner Turbidit-Fazies vor. Die Aufnahme sedimentologischer Profile sowie zahlreiche neue Graptolithenfunde in den Turbiditen der Nordpuna ermöglichen eine detailliertere sequenzstratigraphische Gliederung der ca. 7000 m mächtigen Sedimentserien sowie eine Analyse des ordovizischen Punabeckens und seiner geodynamischen Entwicklung.

Table of Contents top ↑

Abstract 1
Resumen 3
Zusammenfassung 4
Preface 6
1. Introduction 9
1.1 Regional overview- Location of the study area 9
1.2 Distribution of Ordovician sedimentary and volcanic rocks in the southern
Central Andes 10
1.2.1 Bolivia 10
1.2.2 Northern Chile 11
1.2.3 Argentina 13
1.2.3.1 Precordillera 14
1.2.3.2 Famatina-System 15
1.2.3.3 Sierras Subandinas 15
1.2.3.4 Cordillera Oriental 15
1.2.3.5 Puna 17
1.3 Contradictory model concepts for the geodynamic development of the
Ordovician in the southern Central Andes - Aims of this paper 19
2. The stratigraphy of the Ordovician successions in the Argentinian-Chilean
Puna 20
3. Sedimentology 21
3.1 Introduction 21
3.2 The eastern part of the northern Puna 23
3.2.1 Previous studies 23
3.2.2 Rio Taique and Sierra del Cobre sections (RT, SC) 24
3.2.3 Cordon de Escaya section (CE) 25
3.3 The western part of the northern Puna 25
3.3.1 The Volcanosedimentary Successions of the middle and upper Arenig 25
3.3.1.1 Previous studies 25
3.3.1.2 Rio Huaytiquina section (HY) 26
3.3.1.3 Filon Pircas section (FP) 27
3.3.2 Lower Turbidite System (upper Arenig-Llanvirn) 29
3.3.2.1 Quebrada Juntas section (QJ) 29
3.3.2.2 Morro Coralito section (MC) 29
3.3.2.3 Cerro Agua Chica section (CA) 30
3.3.2.4 Esquina Colorada section (EC) 30
3.3.2.5 Olaroz Grande section (OL) 30
3.3.2.6 Rio Rosario section (RR) 32
3.3.2.7 Rio Grande section (RG) 33
3.3.2.8 Mina Pirquitas section (MP) 33
3.3.2.9 Cordon de la Rinconada section (SR) 34
3.3.2.10 Santa Catalina section (ST) 35
3.3.3 Upper Turbidite System (Llandeilo (-flower Caradoc)) 36
3.3.3.1 Sierra de Lina section (SL) 37
3.3.3.2 Cerro Queta/Sierra de Cochinoca section (SQ) 39
3.4 Sedimentological model of the northern Puna during the Early Ordovician. 39
3.5 Sedimentological model of the northern Puna during the Middle Ordovician 41
3.6 Sedimentary cyclicity and sea-level changes 44
4. Sedimentary petrography 47
4.1 Sedimentary rocks of the eastern part of the northern Puna 47
4.2 Sedimentary rocks of the western part of the northern Puna 48
4.2.1 The Volcanosedimentary Successions 48
4.2.2 The Turbidite Systems 50
4.3 Interpretation 51
5. Geochemical features of the Volcanosedimentary Successions and their
significance for the geodynamic interpretation of the Ordovician Puna-Basin 52
5.1 Introduction 52
5.2 Petrography of the lavas 53
5.3 Geochemical features of lavas and volcanoclastic rocks 53
5.4 Interpretation 57
6. The ,Faja Eruptiva de la Puna Oriental' 60
6.1 The Faja Eruptiva de la Puna Oriental in the northern Puna 61
6.1.1 Outcrop features and petrography 61
6.1.2 Geochemical features 64
6.1.3 Discussion 68
7. Tectonics 72
8. Geodynamics 76
8.1 Bases of a geodynamic model for the Ordovician Puna basin 76
8.1.1 Regional basin development 76
8.1.1.1 Palaeoceanographic factors 77
8.1.2 Geohistory plots 78
8.1.3 Tectonic subsidence 80
8.2 Geodynamic model of the Ordovician Puna basin: from back-arc- to
foreland basin 81
References 98