Dating igneous volcanic rocks
The Auckland Islands lie approximately 375km south of Stewart Island on the Campbell Plateau.These islands were formed by multiple geological events.The Auckland Islands consist mainly of basalt, but there are also some occurrences of granite, gabbro, sandstone, conglomerate and limestone.Basalt, granite and gabbro are all igneous rocks – they form when magma rises from the mantle and cools.Conglomerate is a type of sandstone that contains a wide variety of particle sizes.Both sandstone and conglomerate are what is known as clastic sedimentary rocks, where mineral fragments from any of the three major rock groups accumulate and lithify (compact and cement)..pass_color_to_child_links a.u-inline.u-margin-left--xs.u-margin-right--sm.u-padding-left--xs.u-padding-right--xs.u-absolute.u-absolute--center.u-width--100.u-flex-align-self--center.u-flex-justify--between.u-serif-font-main--regular.js-wf-loaded .u-serif-font-main--regular.amp-page .u-serif-font-main--regular.u-border-radius--ellipse.u-hover-bg--black-transparent.web_page .u-hover-bg--black-transparent:hover.
One of the first things you can do to determine the geological history of an area is to look at the types of rocks that are present.
In order to gather this information geologists need to use absolute dating techniques.
Absolute dating needs only a small sample of the rock or fossil and can give an ‘exact’ age for that sample.
Available samples of oceanic basalt have all proved to be young.
In those cases where carbonate sedimentary rock overlies the basalt, the carbonate deposition occurred shortly after the formation of the volcanic mountain or basaltic floor.