spitzbergen-3
fb  Spitsbergen Panoramas - 360-degree panoramas  de  en  nb  Spitsbergen Shop  
Marker

Magmatic rocks or magmatites
(rocks derived from melting)

The ori­gin of every mag­ma­tic rock is mol­ten rock mass. For the result, the kind of rock which was mol­ten is an important fac­tor, as it pro­vi­des the che­mi­cal mate­ri­al which can then be re-used. Sim­pli­fied, the­re are ‘aci­dic’ mag­ma types which are simi­lar to gra­ni­tes and ‘basic’ ones which che­mi­cal­ly resem­ble basalt. The terms ‘aci­dic’ and ‘basic’ do not have anything to do with the pH value, but with the amount of sili­ca (SiO2): the more sili­ca, the more ‘aci­dic’. Aci­dic lava (mag­ma which has reached the sur­face) tends to be very vis­cous, but other fac­tors such as tem­pe­ra­tu­re, con­tent of flu­ids (water, CO2 and others) also play an important role. 

Most mag­mas cool down way below the sur­face to form Plu­to­ni­tes; lar­ge rock bodies such as gra­ni­te which can com­pri­se many km3

Dark (‘basaltic’) intru­si­on in light-grey gra­ni­tic rocks (Ant­arc­tic Pen­in­su­la).

Some­ti­mes, smal­ler volu­mes of mol­ten rocks fill weak zones such as cracks wit­hin the pre-exis­tent rocks, forming so-cal­led intru­si­ons. Basaltic intru­si­ons are com­mon in many are­as and are visi­ble as dark stri­pes.

Small gra­ni­tic vein in Rypefjord (inner Scores­by­sund)

Small granitic vein in Rypefjord (inner Scoresbysund)

If mag­ma comes to the sur­face, a vol­ca­nic erup­ti­on will be the result. The­re is a lar­ge num­ber of dif­fe­rent erup­ti­on mecha­nisms and an end­less choice of rocks which can be for­med as a result; they are collec­tively cal­led vol­ca­ni­tes or sim­ply lava.

Back

BOOKS, CALENDAR, POSTCARDS AND MORE

This and other publishing products of the Spitsbergen publishing house in the Spitsbergen-Shop.

last modification: 2013-10-12 · copyright: Rolf Stange
css.php