Sea level curve

High and low stands of sea level are directly recorded as sedimentary coastal onlap sequences and as erosional terraces. These records are complicated in regions of crustal instability, and the rate and nature of crustal deformation determines whether evidence of short-term or long-term sea-level fluctuations are preserved and how easily this evidence is interpreted. Because continental basement warps and fractures through time, and because evidence of sea level is erased by erosion, the interpretation of this evidence to produce sea-level curves for the Phanerozoic has been a subject of considerable debate. 

Phanerozoic trends In the 1970 s, Vail and colleagues (e.g., Vail et al., 1977) using seismic stratigraphic data to determine the extent of onlap of coastal deposits in marine sequences derived a relative sea level curve for the Phanerozoic. The latest representation of this curve is shown in Figure 10.13, and compared with that... 

Figure 10.13. Two interpretations of the Phanerozoic sea level curve. A. Hallam, 1984. B. Vail et al., 1977.

Figure 10.18. Number of occurrences of Phanerozoic ironstones (upper diagram, data from Van Houten and Bhattacharyya, 1982) and odlitic limestones (lower diagram, data from Wilkinson et al., 1985) as a function of geologic age. The relative sea level curve is that of Hallam (1984). Minima in occurrences appear to correlate with times of sea level withdrawal from the continents and major cycles of orogenesis (Caledonian, Hercynian, and Alpine).

The Period-averaged mass ratio of calcite to dolomite (Figure 10.29) is relatively high for Cambrian, Permian, and Tertiary System rocks, whereas this ratio is low for Ordovician through Carboniferous age sediments and rises in value from the Triassic through the Recent. The generalized sea level curve of Vail et al. 

Figure 10.29. The Phanerozoic distribution of the mass ratio of calcite/dolomite in sedimentary carbonates as a function of age. The relative sea level curve is that of Vail et al. (1977). In general, times of low sea level seem to be times of high calcite/dolomite ratios in sedimentary carbonates.

Figure 2.2 Sea level curve during the Holocene. (From Curray, 1965, with permission.)...

The sea-level curves in Figure 19 have two maxima. In the Hardie (1996) model these maxima are taken to coincide with maxima in the rate of seawater cycling through MORs and hence to minima in the concentration of Mg and sol in the contemporaneous seawater. To that extent the predictions of the Hardie (1996) model agree well with the fluid inclusion data... 

For the reconstiTiction of coastline change in the Baltic relative sea-level curves for the last 8000 year can be used (Rosentau et al., 2007). They are derived from data of ancient nearshore sediments. To illustrate the general pattern of sea-level change in the Baltic area, eight typical curves are shown in Fig. 14.4. Each curve mirrors the effects of both eustatic sea-level... 

FIGURE 14.4 lypical relative sea level curves around the Baltic Sea (after Rosentau et al.. 2007). 

TABLE 14.1 References of Typical Relative Sea-Level Curves Shown in Fig. 14.4... 

Uscinowicz, S., 2006. A relative sea-level curve for the Polish Southern Baltic Sea. Quaternary International, 145-146, 86-105. 

Fig. 13. Burial and thermal history diagram of the Namorado turbidites in the Abacora Field (B). Note in the relative sea-level curve of Vail et al. (1977) (A) that at the time of the turbidite deposition there was a s nificant sea-level fall (Cenomanian). The low sea-level stand favoured meteoric water invasion at this time.

---