Geoscience Reference
In-Depth Information
(a) Deltaic setting
Periodic breaching transports
suspended sediment into
adjacent areas
Flood-derived
inorganic silts
and clays
High
in situ
organic
production
High (seasonal)
fluvial inputs
Limited marine
influence
R
R
R
R
A
A
R
A
A
A
A
A
A
A
A
L
L
L
Lagoon
Oxidation reactions lead to
iron/calcareous nodule formation
Facies 2 - Levee deposits
- inorganic silts/clays
Facies 4 - Mudflats
- inorganic fine sand-silt-clay
Trapping of organic and inorganic
sediment around vegetation
Facies 1 - Distributary channel fill
- organic muds + inorganic silts/clays
Facies 3 - Interdistributary basin fills
- autochthonous organic sediment
(b) Estuarine setting
Extensive trapping of suspended
sediment in and around vegetation
Grain flocculation - enhanced
by high microbial productivity
in nearshore creeks
Limited fluvial
inputs
High marine
sediment
inputs
R
A
R
R
R
Inputs of reworked
clastic dune sands
C
R
A
B
C
A
Facies 2 - Low tide muds
- clay and silt with variable
carbonate content
Facies 3A - Upper creek deposits
- terrigenous sands
Facies 1 - Intertidal mudflats
- organic muds, silts
Facies 3C - Lower creek deposits
- shell lags
Facies 3B - Middle creek deposits
- organic muds, silts
(c) Open carbonate coast
High marine
sediment
inputs
Little/no fluvial
inputs
Sediment trapping
around plant roots
Localised precipitation of calcite
and aragonite within microbial mats
Organic inputs
(increase in
upper intertidal)
Aeolian sands from
surrounding dunes
Skeletal carbonates
washed into creeks
from shallow marine
sands
A
A
A
A
A
A
A
A
A
Extensive binding of
sediments by algal mats in
upper intertidal zone
Facies 1 - Intertidal sands
- quartz: carbonate wackestone/packstone
Facies 2 - Nearshore sands
- coarse shelly grainstone
Fig. 9.14
Schematic diagrams illustrating the sediment facies associated with different mangrove settings. (a) Deltaic setting - based
on the Grijalva-Usumacinta delta in Tabasco and Campeche, Mexico. Mangrove genera: A,
Avicennia
; R,
Rhizophora
; B,
Bruguiera
;
C,
Ceriops
; L,
Languncularia
. (Based on Thom 1967.) (b) Estuarine setting - based on Coral Creek, north-east Australia. (Based on
Grindrod & Rhodes 1984.) (c) Open carbonate-dominated shoreline - based on Spencer Gulf and Gulf of St Vincent, South Australia.
(Based on Butler et al. 1977.)
