Quaternary%20Sea-level%20Change

1
Quaternary Sea-level Change
2
(No Transcript)
3
(No Transcript)
4
(No Transcript)
5
I. Appropriated and Inappropriated Technology
A. Stratigraphy Context of Study Materials
There are lots of good types of data to work with
and there are lots of pitfalls. 1.
Morphostratigraphic units Coral-reef terraces
and former strand-line complexes in clastic
sediments are examples of morphostratigraphic
units. 2. Layer-cake stratigraphy (column) a.
Bad examples of this practice exist especially
where geologists correlate on the basis of
questionable radiometric dates rather than on the
basis of physical characteristics or
stratigraphic continuity. b. Deep-sea cores
from many portions of the world ocean sample an
extremely reliable "layer-cake stratigraphy".
6
3. Peats It can be easily dated using the
C-14 method and it is difficult to move peats
around as sea-level moves up and down. 4. Mollusk
shells a. If mollusc samples are to have
stratigraphic integrity, one must be able to
demonstrate that the shells have not been
transported by rising sea-level, subsequent
current activity, seagulls, or man. b.
Contamination 5. Corals a. Reef-crest corals
(Acropora palmata) can be outstanding indicators
of paleosea-level. b. The coral did not live
above sea-level but beyond that, things get
complicated. 6. Beach Rocks The claim that
"beach rock" identifies a former intertidal
environment must be held to close scrutiny.
7
B. Geochronology/Chronostratigraphy
1. C-14 dating One would hope that all the
material would have met selection criteria but
in fact this is not the case and much of existing
data must simply be regarded as irrelevant to the
questions under consideration. 2. Uranium-series
dating a. One simply cannot trust dates on
sparse samples from a single or a few terraces.
b. One simply should not trust uranium-series
dates on materials that were collected from
within the modern freshwater phreatic lense or
that can be demonstrated to have resided in a
paleophreatic lense at some time in the history
of the sample. 3. Magnetic stratigraphy 4. The
SPECMAP Time Scale 5. Other methods nanno
fossil, thermoluminescence dating(TL), optical
stimulated luminescence dating(OSL), electron
resonance dating, fission track, amino acid.....
8
(No Transcript)
9
(No Transcript)
10
(No Transcript)
11
(No Transcript)
12
(No Transcript)
13
(No Transcript)
14
(No Transcript)
15
(No Transcript)
16
(No Transcript)
17
(No Transcript)
18
(No Transcript)
19
(No Transcript)
20
(No Transcript)
21
(No Transcript)
22
(No Transcript)
23
(No Transcript)
24
(No Transcript)
25
(No Transcript)
26
(No Transcript)
27
(No Transcript)
28
II. The 180 to 18 kaBP Time Interval

• pick up information concerning maximum sea-level
  fluctuation from glacial to interglacial
  conditions
• pick up important calibration concerning the
  relative importance of ice-volume variation and
  temperature variation in the observed d18O curve
  from deep-sea cores

29
A. Coral-Reef Terrace Sequences
On the basis of the record within the range 14C
dating, it appears that only the d18O signal in
deep-sea cores covaries with the sea-level signal
from submerged shoreline. a. well-dated
morphostratigraphic units 1. Barbados
(Mesolella et al., 1969 Bender et al., 1979)
2. New Guinea (Bloom et al., 1974 Aharon, 1983)
3. Haiti (Dodge et al., 1983) 4. the New
Guinea terrace sequence contains several younger
terraces that are not represented on Barbados or
Haiti because the uplift rate of Barbados and
Haiti is considerably less than the uplift of the
New Guinea terrace sequence
30
b. The Constant Uplift Rate Hypothesis 1.
with the work of Stockmal(1983) this assumption
seems reasonable for a relatively simple tectonic
setting such as Barbados, but this assumption is
not easily justified for such complex areas as
New Guinea or Haiti 2. we should be thankful
for the uplifting of these terrace but should
not rely on the "constant uplift hypothesis" to
tell us anything about relative sea level 3.
this hypothesis remains substantially ad hoc and
can considered valid at this time only on an
empirical, statistical basis
31
(No Transcript)
32
(No Transcript)
33
(No Transcript)
34
(No Transcript)
35
(No Transcript)
36
(No Transcript)
37
(No Transcript)
38
(No Transcript)
39
(No Transcript)
40
(No Transcript)
41
(No Transcript)
42
(No Transcript)
43
(No Transcript)
44
(No Transcript)
45
(No Transcript)
46
(No Transcript)
47
(No Transcript)
48
(No Transcript)
49
(No Transcript)
50
(No Transcript)
51
(No Transcript)
52
(No Transcript)
53
(No Transcript)
54
(No Transcript)
55
(No Transcript)
56
(No Transcript)
57
(No Transcript)
58
(No Transcript)
59
(No Transcript)