Abstract--In many half-graben, strata progressively onlap the hanging
wall block of the basins, indicating that both the basins and their depositional
surface areas were growing in size through time. Based on these constraints,
we have constructed a quantitative model for the stratigraphic evolution
of extensional basins with the simplifying assumptions of constant volume
input of sediments and water per unit time, as well as a uniform subsidence
rate and a fixed outlet level. The model predicts (1) a transition from
fluvial to lacustrine deposition, (2) systematically decreasing accumulation
rates in lacustrine strata, and (3) a rapid increase in lake depth after
the onset of lacustrine deposition, followed by a systematic decrease.
When parameterized for the early Mesozoic basins of eastern North America,
the model's predictions match trends observed in Late Triassic-age rocks.
Significant deviations from the model's predictions occur in Early Jurassic-age
strata, in which markedly higher accumulation rates and greater lake depths
point to an increased extension rate that led to increased asymmetry in
these half-graben. The model makes it possible to extract from the sedimentary
record those events in the history of an extensional basin that are due
solely to the filling of a basin growing in size through time and those
that are due to changes in tectonics, climate, or sediment and water budgets.
|Quantitative filling model for continental extensional
basins with applications to early Mesozoic rifts of eastern North America
Figure 1 [18 k] Cross section and seismic lines
of typical half graben.
Figure 2 [9 k] Full-graben geometry.
Figure 3 [18 k] Full-graben basin filling model.
Figure 4 [14 k] Half-graben basin filling model.
Figure 5 [18 k] Mesozoic rift basins of eastern
Figure 6 [27 k] Stratigraphy of the Newark
basin and accumulation rate data.
Figure 7 [32 k] Geologic map of the Newark
Figure 8 [14 k] Cross section of the Newark
basin, palinspastic reconstruction, and full-graben equivalent.
Figure 9 [27 k] Predictions of the basin filling
model for the Newark basin.
Figure 10 [14 k] Effects of asymmetric basin
Figure 11 [23 k] Chronostratigraphy and accumulation
rate data for Mesozoic rift basins of eastern North America.
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