McGinnis (1968) stated that crustal uplift (a forebulge
) occurs in proximity to an ice margin because of crustal deflection beneath the ice.
During this time wave base may have contributed to suabaquatic erosion to levels now at depths >60 m, depending upon local isostacy and forebulge
The Fennoscandian postglacial rebound and glacial forebulge
in relation to the underlying tectonic stress have engendered a pattern of alternating regions of higher and lower seismicity, whereas evidences of active faulting and seismicity are mostly connected to the areas where ice sheets reached their maximum thickness, including the marginal regions (Morner 2003; Steffen & Wu 2011; Hoffmann & Reicherter 2012; Brandes et al.
Seisms concentrate toward the SE of the Madrid Basin, owing to a flexural forebulge
, and in basement faults at the southern edge of the Central System (Fig.
One area, the Bisoni-McKay, at the south end of the Fish Creek Range, displays an olistostrome, shed eastward during the Late Devonian (early Famennian) from a migrating Antler orogenic forebulge
. The other area, the Warm Springs-Milk Spring, at the south end of the Hot Creek Range, displays a deeper marine terrane affected by the Late Devonian (middle Frasnian) Alamo impact.
At the margins of the Guayana Shield and in the outer areas of the peripheral forebulge
was deposited the Eocene Caratas Formation, marking the end of the continental passive margin stage in Northeastern Venezuela.
In addition, on the distal part of a foreland basin (such as Tingri and Gamba), the forebulge
will occur earlier than the foredeep, and consequently the age of the forebulge
may better constrain the timing of the IIACC.
The initial fall in sea level after deglaciation was caused by isostatic rebound and the passing of a crustal forebulge
northward across the region.
It was followed by development of an Acadian forebulge
and foredeep which migrated northwestward from coastal Maine through the study area until the Middle Devonian.
In a tectonic loading cycle, the foreland basin system is similar to that of the DeCelles and Giles model (1996) and consists of the four depozones i.e., the wedgetop depozone, the foredeep depozone, the forebulge
depozone and the backbulge depozone.