Deformation, erosion and natural resources in continental collision zones [Elektronische Ressource] : insight from scaled sandbox simulations / Geoforschungszentrum Potsdam, Stiftung des Öffentlichen Rechts. Vorleget von Silvan Hoth

Hoth

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• Publié par: freie_universitat_berlin
• Publié le: 01 janvier 2006
• Nombre de lectures: 40
• Poids de l'ouvrage: 27 Mo

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ISSN 1610-0956
Scientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamDeformation, erosion and natural resources
in continental collision zones
Insight from scaled sandbox simulations
Dissertation
zur Erlangung des akademischen Doktorgrades
doctor rerum naturalium (Dr. rer. nat.)
im Fachbereich Geowissenschaften
der Freien Universität Berlin
vorgelegt von
Silvan Hoth
Potsdam, August 2005
Scientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamTag der Disputation: 09. November 2005
Gutachter
Prof. Dr. Onno Oncken (1. Gutachter)
Freie Universität Berlin, GeoForschungsZentrum Potsdam
Prof. Dr. Manfred Strecker (2. Gutachter)
Universität Potsdam
Scientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamSie begriffen, daß die Vernunft nur das einsieht, was sie selbst
nach ihrem Entwurfe hervorbringt, daß sie mit Principien ihrer Ur-
theile nach beständigen Gesetzen vorangehen und die Natur nöthi
gen müsse auf ihre Fragen zu antworten, nicht aber sich von ihr
allein gleichsam am Leitbande gängeln lassen müsse; denn sonst
hängen zufällige, nach keinem vorher entworfenen Plane gemachte
Beobachtungen gar nicht mit einem nothwendigen Gesetz zusam
men, welches doch die Vernunft sucht und Bedarf...
Immanuel Kant, Zweite Vorrede zur Kritik der reinen Vernunft, Königsberg, 1787
Scientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamScientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamContents
Summary iii
Zusammenfassung v
1 Introduction 1
2 Orogen scale erosion 5
3 Continental collision zones 13
3.1 Kinematic concepts of bivergent orogens . . . . . . . . . . . . . . . . . . . . . . . . . 13
3.2 models of fold and thrust belts . . . . . . . . . . . . . . . . . . . . . . . . 13
3.3 The Critical Coulomb Wedge concept . . . . . . . . . . . . . . . . . . . . . . . . . . 17
3.4 The minimum work concept of mountain building . . . . . . . . . . . . . . . . . . . . 23
4 Experimental method 25
4.1 Physical properties of analogue materials . . . . . . . . . . . . . . . . . . . . . . . . 26
4.2 Experimental setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
4.3 Data acquisition and processing with Particle Image Velocimetry . . . . . . . . . . . . 34
4.4 Data mining and its limitations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 36
5 Kinematic boundary conditions and their influence on bivergent wedge evolution 41
5.1 Reference experiment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
5.2 Experiments with other kinematic boundary conditions . . . . . . . . . . . . . . . . . 50
5.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
5.3.1 Four staged evolutionary model for bivergent sand wedges . . . . . . . . . . . 65
5.3.2 Strain transfer in bivergent wedges . . . . . . . . . . . . . . . . . . . . . . . . 66
5.3.3 The timing of thrust initiation . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.3.4 The spacing of thrusts . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 72
5.3.5 Frontal accretion in the retro wedge . . . . . . . . . . . . . . . . . . . . . . . 73
5.3.6 Parameter combinations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75
5.3.7 Self similar growth . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 76
5.4 Implications and predictions for natural bivergent wedges . . . . . . . . . . . . . . . . 77
5.5 for erosion experiments . . . . . . . . . . . . . . . . . . . . . . . . . . . 82
i
Scientific Technical Report STR 06/06 GeoForschungsZentrum Potsdamii Contents
6 The influence of erosion on bivergent wedge evolution 83
6.1 Reference experiment without erosion . . . . . . . . . . . . . . . . . . . . . . . . . . 83
6.2 Experiments with erosion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
6.3 Discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 95
6.3.1 Concepts of bivergent wedge evolution and the accretion cycle . . . . . . . . . 95
6.3.2 Discrete erosion versus continuous deformation . . . . . . . . . . . . . . . . . 95
6.3.3 Influence of erosion on bivergent wedge kinematics . . . . . . . . . . . . . . . 98
6.4 Implications and predictions for natural orogens . . . . . . . . . . . . . . . . . . . . . 100
7 Deformation versus erosion 103
8 Foreland basin evolution and the growth of an orogenic wedge 105
8.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 105
8.2 Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 106
8.3 Results and discussion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107
9 Perspectives 111
Acknowledgements 113
References 115
Appendices 129
A Abbreviations and symbols 131
B Supplementary data on DVD 133
C Technical specifications of tested springs 135
D List of experiments 137
Curriculum vitae 141
Scientific Technical Report STR 06/06 GeoForschungsZentrum PotsdamstBased on the 1 experimental series we sug Summary
gest a four staged evolutionary model for biver-
gent orogenic wedges. An initial crustal scaled
pop up (stage I) or backfold is followed by a proto
pro wedge, in which frontal accretion dominatesMountain belts result from the interaction between
(stage II). Basal accretion commences if a mid deformation, flexure and surface processes. Previ
crustal detachment is present (stage III). Frontalous research has either focused on the mechanics
accretion within the retro wedge occurs duringof orogenic evolution and thereby paid special at
stage IV.tention to its shape, or on the influence of surface
processes on deformation. Thus, both attempts We propose the conceptual model of an ac
follow the bird‘s eye view. However, conceptual cretion cycle. Each accretion cycle consists of
models such as the Critical Coulomb Wedge con a thrust initiation, an underthrusting and a re
cept or the forward and the backward breaking activation phase, where the first and the third
model of thrust propagation provide only little to phase of two consecutive accretion cycles are co
no predictive power with respect to the magnitude eval. It follows that strain transfer between thrusts
and location of deformation and surface uplift. We is a gradual process. Furthermore, each accre
therefore aim to elucidate the spatio temporal evo tion cycle initiates a surface uplift and a strain
lution of strain partitioning within and the associ wave at the toe of the pro wedge and both mi
ated surface uplift of bivergent wedges. However, grate coevally towards the retro wedge. Thereby,
such a methodological approach would require the strain accumulation and surface uplift depend on
view from below. the phase within the accretion cycle and thus vary
predictably in space and time. Although Mohr-This challenge is addressed with two series of
Coulomb is time independent, strain hardeningsandbox experiments, each with a specific pur-
st and strain softening processes within fault zonespose. The 1 experimental series was designed
determine the timing and magnitude of slip. Weto analyse the influence of flexure, the mechanic
therefore consider the accretion cycle as an inter-stratigraphy as well as the strength contrast be
nal clock of orogenic deformation.tween the lower and the upper plate on the ratio be
tween internal deformation versus foreland ward We strongly emphasise that this conceptual
ndpropagation of deformation. With the 2 exper- model combines previously unrelated observa
imental series, special emphasis was devoted to tions, such as the periodicity of thrusting, the topo
the effect of the location of erosion with respect to graphic evolution of bivergent wedges and the cu
the convergence geometry as well as the mode of mulative slip history of thrusts. Additionally, this
erosion on the tectonic mass transfer in bivergent conceptual model highlights farfield connections
wedges. between the initiation of a new thrust within the
pro layer (cause) and the resulting “strain and up We introduce a setup, which allows for the first
lift pulse” at the retro shear zone (response). How time in sandbox experiments, the simulation of
ever, the degree of “strain communication” be load driven flexure. Incorporation of Particle Im
tween the pro and the retro wedge decreases, asage Velocimetry provided time series of the incre
the former grows laterally.mental displacement field and its derivates such as
horizontal shear strain. To facilitate interpretation Surface uplift of the pro wedge is highly
and to successfully communicate results, two new episodic and reflects individual accretion cycles.
display types, i. e., the surface uplift and the evo Thereby, re activation of thrusts leads to order-
lution of deformation map are introduced. of magnitude variations in surface uplift. Thus,
iii
Scientific Technical Report STR 06/06 GeoForschungsZentrum Potsdamiv Summary
changes of the kinematic or mechanic boundary cause (retro wedge erosion) and response (defor-
conditions as well as surface processes