Post-Paleozoic activity - Lamont-Doherty Earth Observatory ...
Post-Paleozoic activity - Lamont-Doherty Earth Observatory ...
Post-Paleozoic activity - Lamont-Doherty Earth Observatory ...
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Strata within these Mesozoic basins are also cut by major<br />
oblique-trending cross faults, Sanders (1963) reports that in the<br />
Newark basin some faults have as much as 20 km of horizontal<br />
displacement and 3 km of vertical displacement, and Van Houten<br />
(1969) reports that some northeast-trending strike-slip faults in<br />
the Newark basin may be part of a strike-slip system involving<br />
the Ramapo border fault (Fig. 5). Published geophysical and<br />
subsurface data from the Newark-Gettysburg basin (Sumner,<br />
1977; Cloos and Pettijohn, 1973), the Hartford basin (Wenk,<br />
1984), the Durham basin (Bain and Harvey, 1977), and the<br />
Sanford basin (Deep River; Randazzo and others, 1970) show<br />
that the basement is cut by cross faults creating intrabasin grabens<br />
and horsts that, most probably, formed early and concurrently<br />
with the onset of sedimentation (see Sumner, 1977; Cloos and<br />
Pettijohn, 1973). However, field data (e.g., Faill, 1973; Lucas and<br />
^<br />
-J -r<br />
-'<br />
0 I-<br />
I-<br />
-<br />
2-<br />
-<br />
3-<br />
-<br />
NW<br />
<strong>Post</strong>-<strong>Paleozoic</strong> <strong>activity</strong> 329<br />
USGS LINE 9 LONG ISLAND BASIN<br />
S P* 400 500 600<br />
others, 1988) also show that some rift-related deformation of the<br />
onshore basins postdates the youngest rift strata (Early Jurassic)<br />
and may have continued through the Middle Jurassic, when sea-<br />
floor spreading and drifting began offshore. Seismic profiles<br />
across the passive margin show that, except for intrusions by salt<br />
and igneous rocks, the younger drift strata appear essentially<br />
undisturbed (Figs. 8,9).<br />
That the onshore rift basins have been deformed during the<br />
drifting phase is supported by many studies, including McHone<br />
and Puffer (this chapter) and Prowell (this chapter). The defor-<br />
mational continuum and complexity is documented in field stud-<br />
ies of the north-trending Hartford basin, where de Boer and<br />
Clifford (1988) and Wise (1982) show that late Triassic faulting<br />
was accomplished by oblique slip with a dextral shear component<br />
along north-south (grain parallel) fractures in the basement. As<br />
S P# 400 500 600 700<br />
I I I I I I 0<br />
T/UK TERTIARY /QUATERNARY<br />
T/LK<br />
UPPER CRETACEOUS<br />
Figure 8. Seismic-reflection profile and interpreted line drawing of USGS line 9, showing the Long<br />
Island basin beneath the post-rift unconformity. The low-angle western border fault, tilted (sedimen-<br />
tary?) horizons, and high-angle cross faults can be identified on this profile. PRU: post-rift unconformity,<br />
T/UK: top of Upper Cretaceous, T/LK: top of Lower Cretaceous, T/UJ: top of Upper Jurassic. Figures<br />
and caption from Hutchinson and others, 1986.<br />
SE<br />
LOWER CRETACEOUS - I<br />
-<br />
-<br />
CRYSTALLINE<br />
BASEMENT - 2<br />
5 KM<br />
O- -3<br />
-<br />
-