Here are images of the huge Achala batholith structure which has been up-heaved in
an area near Cordoba, Argentina. There are at least four magma suites within this
batholith and each section has emerged at a different stage (M.Demange et al, 1996).
The massive uplifted granite batholith in the distance.
On the top of the batholith, looking down to the lower terrace.
It is likely that the higher section of the terraced batholith emerged first. The
lower terrace will have emerged as a lateral intrusion at the side of the first ‘plug’.
As with most volcanism, the first to break through the crust has the most energy
and subsequent intrusions have lower energy levels. The basin in the mid-distance
is likely to be a third intrusion of less energy still and this will unlikely emerge
but just power the spreading of the basin area between the original batholithic structures.
Dorais et al, date the batholith at around 348 mya, in the early Carboniferous Period.
According to my Small Earth Model, see Pangaean Earth Section, the palaeo-equator
ran along the length of the Andes Mountains. This is consistent with my suggestion
that igneous activity is most prominent along contemporary equatorial lines.
The Halfway House Granite Dome, South Africa
The Halfway House granite dome probably formed when this part of South Africa was
on the equator (Late Triassic?). Like a batholith it initially developed by the upwelling
of a mantle plume but stayed below the surface of overlaying sedimentary rock. Here
it accreted as an enormous ‘plug’. Subsequently, when perhaps the area was back on
the palaeo-equator (early Jurassic times?) it was subjected to further hydrostatic
uplifting which caused it to burst through the overlaying sedimentary structure.
Sugar Loaf Mountain Rio de Janeiro,Brazil
The Halfway House Granite Dome.
Video which illustrates the development of a granite dome or batholith