Geology Reference
In-Depth Information
Age (Ma)
0
1
2
3
4
5
6
7
8
0
Platform
aggradation
CLINO
50
Sr-isotope age
range-celestite
100
SSB-C
150
Rapid sediment accumulation
associated with prograding
clinothem (= LOADING)
200
250
d
Early cementation of
coarse-grained skeletal
'interruptions' ?
300
350
'Background' hemipelagic
SSB-D
Fractures
400
e
'Background' hemipelagic
Fractures
SSB-E
450
Fig. 9.
Age-depth plot for core Clino
from McNeill
et al
. (2001). The upper,
middle and lower fracture intervals
are shown in middle Pliocene age
host sediments. Progradation loading
above SSB-D in the latest Pliocene
rapidly added over 300 m of sediment
on top of the skeletal 'interruptions'
to produce compression fractures.
'Background' hemipelagic
f
500
SSB-F
550
BASIN
PLATFORM
Progradational loading
Extentional
fractures
(compaction)
Extentional
(axial split)
fractures
Shear
load fractures
(conjugate?)
76º-90º
(Saller, 1996)
Uncemented
hemipelagic
SSB-D
Cemented
skeletal
'interruption'
Depositional slope angle = ~5º
Uncemented
hemipelagic
Fig. 10.
A cartoon summarizing the
general forces and fracture types at the
progradational margin of western Great
Bahama Bank. The key to early fracture
is the preferential early cementation of
the skeletal 'interruption' beds.
Platform
Basin
