Beckenanalyse - sediment.uni-goettingen.de · Subsidenz ist eng verknüpft mit dem Prinzip der...

Beckenanalyse1. Subsidenz

Hohe Sediment-Akkumulation und die Bildung Sedimentärer Becken sind nicht möglich ohneentsprechenden Subsidenz. Subsidenz beschreibt die Senkung der Erdoberfläche (Landober-fläche oder Meeresboden) bzw. der Basis des Sedimentbeckens relativ zum Erdmittelpunkt (bzw. eines Bezugniveaus konstanten Drucks in der viskosen Asthenossphäre, s.u.).

Subsidenz ist eng verknüpft mit dem Prinzip der Isostasie: die Hebung (oder Senkung) der Erdoberfläche ist eine Funktion der Dichte und Dicke h der unterschiedlichen Lagen (Schalen). Vereinfacht sind dies: Meerwasser (w), Sediment (s), konsolidierte Kruste (c), lith hä i h M t l ( ) d t hä i h M t l ( ) Di M üb ilithosphärischer Mantel (m) und astenossphärischer Mantel (a). Die Masse über einemBezugniveau konstanten Drucks in der viskosen Asthenossphäre

whw + shs + chc + mhm + aha = c

Ein Beispiel zur Größenordnung (unter vereinfachten Bedingungen; Wasserfüllung, kein Sediment): Eine durch Extension bedingte Verdünnung der Kruste auf 15 km (statt normalen ca 30 km) führt zu einer Subsidenz von Meeresspiegelniveau auf 3 5 km Wassertiefe

HvE / Fazies- und Beckenanalyse

ca. 30 km) führt zu einer Subsidenz von Meeresspiegelniveau auf 3,5 km Wassertiefe.

Einsele 2000


Einsele 2000


Initiale (tektonische) vs thermische Subsidenz

Einsele 2000


Flexural response of thelithosphere due to crustallithosphere due to crustalor sediment loading

Einsele 2000Einsele 2000


Harwood et al. 2005Harwood et al. 2005


Fig. 27.7 Cartoon to show how shortening across a deepFig. 27.7 Cartoon to show how shortening across a deepthrust fault causes a regional load, which must flexure the whole brittle lithosphere and cause deeper compensatory viscoplastic flow (from Felemings & Jordan 1990).

Leeder1999


Leeder 1999

S hl l (1997) T i 16

10 kmEUSM Sedimentation Model (Chattian ~25Ma)

Schlunegger et al. (1997), Tectonics 16Floodplain

S

Rofluvial

N S

RigiAFCC

Boswil-1 Hünenberg-1

belt

25 Ma

meander

4

km

N SChurfirstenWattwil R

basement

0

-4

0 30 km

UMM


0 30 km

Jurassic/Cretaceous Alps (Helvetic) UMM (Rupelian)USM (Chatt./Aquit.)

OMM (Bur./Lan.)OSM (Lan./Tor.)

Backstripping 1. Dekompaktion

HvE / Fazies- und BeckenanalyseEinsele 2000

2. sediment load – isostasy

(3 paleo bathymetry & sea level change)


(3. paleo-bathymetry & sea-level change)

Young rift zonesou g t o es

Einsele 2000


passive margin subsidence models

SA

mor

e, U

Sor

Bal

timS

chel

f vo

Atla

ntik

-Sh

den

Aof

il du

rc


Pro

nach Bouma et al. (1982)


cm/ka Grand Banks area( ff N f dl d)(off Newfoundland)

Einsele 2000


Einsele 2000

Grand Banks area( ff N f dl d)(off Newfoundland)

a, b

Einsele 2000


Einsele 2000

ins

nd b

asi

fore

lan

f

HvE / Fazies- und Beckenanalyse Einsele 2000

Beckenanalyse 2. Genetische stratigraphische Konzepte

0se

le 2

00E

in


CYCLIC BEDDING

00ns

ele

20E

i


Sequenzstratigraphie

Das Konzept der Sequenzstratigraphie beruhtauf dem Zusammenspiel von Sedimentzufuhr und Akkomodationsraum, letzterer wird gesteu-

t üb t ti h M i l h kert über eustatische Meeresspiegelschwankun-gen und Subsidenz bzw. Hebung (Raten!).


Coe et al. 2003

sedimentary response tosedimentary response toperturbations of the equilibrium profile caused by uplift / subsidence y pand/or sea level change

HvE / Fazies- und Beckenanalyse Coe et al. 2003

The simplest way to understand sequence stratigraphy is to consider the interface area between coastal and shallow-marine siliciclastic depositional environments where changes

The parasequence forms the smallest and simplest unit in the framework of sequence

between coastal and shallow marine siliciclastic depositional environments where changesin relative sea level are easiest to interpret.

The parasequence forms the smallest and simplest unit in the framework of sequencestratigraphy. It results from a small-amplitude, short-term oszillation in the balance between sediment supply and accomodation space.

Example: coastal environment:


Coe et al. 2003


Coe et al. 2003


Coe et al. 2003


Coe et al. 2003


Parasequence Sets

Coe et al. 2003


Parasequence Sets

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forced regression


Sequences and System Tracts

A sequence or depositional sequence is composed of a succession of parasequence sets. Each sequence represents one cycle of change in the balance between accomodation space and sediment supply. Sequences generally range in thickness from a few meter to tens or even pp y q g y ghundreds of m, and they are the next larger (or longer duration) cycles above parasequences.

Similar to parasequences, sequences are the result of changes in eustatic sea-level and/or subsidence/uplift resulting in a changing relative sea-level ( accomodation space seesubsidence/uplift resulting in a changing relative sea-level ( accomodation space, seebelow), and/or changes in sediment supply.

t ti l l + b id l ti l leustatic sea level + subsidence relative sea-level


Every sequence is composed of up to four systems tracts each of which represents arelative sea-level curves systems tracts, each of which represents aspecific part in the cyclic change in the balance between accomodation space and sediment supply. Each systems tract is made up of atsupply. Each systems tract is made up of atleast one parasequence set. Different conditions may result in one or more of the systems tracts not being developed or y g ppreserved.

The four systems tracts are:Hi h t d S t T t (HST)- Highstand Systems Tract (HST)

- Falling Stage Systems Tract (FSST) - Lowstand Systems Tract (LST) - Transgressive Systems Tract (TST)

The high number of different factors involved in any one geological situation (such as climate, eustatic sea-level change, subsidence rate, sediment supply, lithology, ...) means that the

lt t hi hl i bl

Fig. 4.8b: blue curve taken from Fig. 4.8a; purple curve combines blue curve with short-term changes in

d ti i t d ith

C t l 2003

resultant sequences are highly variable.However, every sequence has similar genetic components related to changes in the rate of accomodation space creation

accomodation space associated withthe development of parasequences.


Coe et al. 2003 the rate of accomodation space creationand sediment supply.

Because the geometry of the basin floor is crucial to the evolution of depositional sequences and systems tracts, we will consider in the following to principal types of depositional profiles from the land to the sea:

shelf break marginshelf-break margin

ramp margin


Coe et al. 2003

The Highstand Systems Tract (HST)


shelf-break margin

(c)

ramp margin(d)

ramp margin

3t a

l. 20

03

HvE / Fazies- und Beckenanalyse Coe

et

Sequence Boundary (SB)


Coe et al.2003

200

3C

oe e

t al.

C

ramp marginramp margin


The Falling Stage Systems Tract (FSST)

HvE / Fazies- und BeckenanalyseCoe et al. 2003

shelf-break margin

(c)

submarine fans deposited at base of continental slope

(d)ramp margin

(d)

3et

al.

2003


Coe

e

Different geometries of Falling Stage Systems Tracts on ramp type margins

increasing rate of relative sea-level fallor (and)d i t f di tdecreasing rate of sedimentsupply

old young


Loss of accomodation space caused by relative sea-level fall

A + B<<

B

C + D D


The Lowstand Systems Tract (LST)


ramp margin

(d)

shelf-break margin(c)

Coe et al. 2003


TransgressiveSurface (TS)

Coe et al 2003


Coe et al. 2003

The Transgressive Systems Tract (TST)

(a)


shelf-break margin

(c)

ramp margin(d)

Coe et al. 2003

( )


Maximum FloodingSurface (MFS)

3t a

l. 20

03

HvE / Fazies- und Beckenanalyse Coe

et

Coe et al. 2003


Coe et al. 2003


Beckenanalyse - sediment.uni-goettingen.de · Subsidenz ist eng verknüpft mit dem Prinzip der...

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