Fig.1. – An illustration of basins in an extensional set up (Source –
google images)
In the case of intracratonic rift basins, although formed within
continental masses in extensional set up, they are normal fault bounded
basin. Most normal faults in rift basins are associated with both
extensional and strike-slip components. In strike-slip presence, when
extensional regime dominates, faulting is called as transtensional
basin. So basin bounding fault zone has more offset on one side of the
rift than the other zone. They are structurally more disturbed. If
rifting continues to operate, there could be possibilities of opening of
oceanic basin along margins of continent (pericratonic). There could be
development of aulacogens or failed rifts in special conditions like a
plume which might lead to a dome like build-up generating three
fractures, two of which could be active in terms of rifting and third
becomes inactive & might be filled with sediment later.
In the case of passive margin basins, they are usually developed at
continent-ocean margins where no subduction is occurring. The more it
accentuates to the oceanic areas away from continental crust, the more
it has potential to allow biogenic processes to work on it and can lead
to formation of carbonate build ups. It is to be noted that if
continental drainage occurs, then siliciclastic sediments can allow
deltaic accumulations to form. This can also lead to sediment loading
due to gravity deformation of basinward transported materials.
While considering the continental margins, in convergent settings
(Fig.2.), we usually come across an oceanic crust subducting below a
continental crust and a trench which may roll-back beneath landward side
of volcanic chain on other side of subduction zone along with
development of volcanic arcs due to accretionary prisms. If accretion to
continental margins is complete, then there can be accreted back-arc and
accreted fore-arc basins.