2
$\begingroup$

Can fissure eruptions dislocate/deform ( fault, rotate, bend, folding) the surrounding strata which fissure ascending into. Or, can a laccolith reach to the surface (and flow) after folding the surrounding strata?

( the magmatic rock on the photo is dacite-rhyodacite according to geochemical analysis)

pi

$\endgroup$
  • $\begingroup$ .... Or, can a lava flow swallow the strata that it flowing over ? $\endgroup$ – Muharrem Yavuz Sep 10 at 19:29
2
$\begingroup$

A fissure eruption typically occurs in basaltic terrain, where the magma is relatively fluid. Hawaii is a great example. Fissure eruptions occur along dilated fault zones. You show a picture of an andesitic unit. This magma has a much different chemistry than basalt, and is generally found in a different geologic terrain, like a convergent plate margin (Japan, South America.) Basalt might form a sill in certain conditions, but not a laccolith. Andesite and granite laccoliths are more common since these magmas are much more viscous/stiff.

Laccoliths almost by definition deform surrounding country rock, the degree to which they do this depends on the size and depth of the laccolith. If the magma from a laccolith reaches the surface it results in a dome or other volcanic ejecta. This portion of the magmma system would not be referred to as a laccolith. It has a root that is a laccolith, but the surface materials have other names.

$\endgroup$
1
$\begingroup$

A fissure eruption can dislocate and cause faults in surrounding strata, but these strata are not plastic enough to be bent and folded in the short term. Strata can be bent and folded, but only if subjected to the sort of pressures exerted by plate movements at great depth over millions of years. Fissure eruptions can reach the surface and flow, but will not bend or fold the strata encountered on the way, though they might fracture it.

$\endgroup$
  • 1
    $\begingroup$ What about soft sedimentary layers like marls and clays? There's no problem with bending those, even at very low pressures. $\endgroup$ – Gimelist Sep 8 at 8:18
0
$\begingroup$

After several days i made a new explanation beyond fissure and laccolith. For refreshing 1-) I have observed the disturbed marl layers 2-) i also saw flowing structures (froth etc.). The problem is how can that these two phenomenon meet for solution. There is one another option to talk about. Exogenus domes, which can bend surrounding layers and able flow (when reaching enough slope angle)

$\endgroup$

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.