Page 41 - Carbonate Sedimentology and Sequence Stratigraphy

32 WOLFGANG SCHLAGER

A) Allison Guyot (pelagics Paleocene-Recent, platform Albian) B) Limalok Guyot (pelagics Eocene-Recent, C) Darwin Guyot
platform Paleocene-Recent) (platform Cretaceous)
1500 m

5 km
16 km 2 km
D) Blake Plateau (pelagics Late Cret.-Recent, E) Campeche Bank (pelagics Late Cretaceous-Recent,
Platform Aptian-Albian) platform Early Cretaceous)
SE NW
W E
2 2
2
3sec

10 km 3sec 3sec
10 km

Fig. 2.25.— Drowned platforms in modern oceans commonly show thin, lens-shaped pelagic caps and significant hiatuses between
platform sediments and pelagic cover. Some platforms have remained virtually bare for 100 My. After Schlager (1999b), modified.

orders of stratigraphic sequences
4 3 2 1

A) Atlantic, Pacific (ODP) N = 23
number of samples 20 8 4
16
12

B) Tethys (Mesozoic) N =56
number of samples 20
June 1986 16
12
Fig. 2.26.— Current record from the top of a seamount in the 8
east Pacific at 500 m water depth. Sluggish currents of few cm/s 4
rise with the diurnal tide to short peaks of over 40 cm/s – enough
10 -1 10 0 10 1 10 2 >10 2
to put sand in motion. The peaks are interpreted as resonance duration of hiatus (my)
between the diurnal tide – generally associated with currents of
few cm/s – and the sharp topography of the seamount. Current Fig. 2.27.— Hiatuses on drowned platforms in the Pacific and
amplification by sharp topography may be one way to produce the Mesozoic Tethys frequently extend to millions of years. Extreme
long hiatuses on drowned carbonate platforms. After Genin et al. examples of over 100 My are among the longest non-tectonic hia-
(1989) and Schlager (1999b), modified. tuses in the Phanerozoic. After Schlager (1999b).