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One such example is just before the formation of the northeast Atlantic Ocean, around 62-55 million years ago, when there were several changes in the relative motions of North America, Greenland, and Eurasia (the combined landmass of Europe and Asia) in just a few million years.A technique called radioisotopic dating allows us to determine the exact age of volcanic rocks.The half-life (the rate at which radioactive decay occurs) of each system varies from milliseconds to billions of years, which means that different isotope systems can be used for dating, depending on how far back in time your interest lies.This is an edited version of Figure 5 from the paper, created using the open source plate tectonics software GPlates by Grace Shephard and Morgan Jones.They were once part of a mountain chain that formed due to Greenland and Svalbard pushing together.This was followed later by sideways movement as the northeast Atlantic Ocean began to open; pulling Greenland and Svalbard apart.The rocks in south-central Svalbard, adjacent to this ancient mountain range, are sedimentary deposits that were formed in deltas and shallow seas.Mountain ranges often have low-lying regions alongside them (called basins) where sediments accumulate.
The orange areas show the rifting zone to the east of Greenland where the northeast Atlantic would later open.
Modern examples include the Po Valley next to the Alps in Italy and the Ganges Basin next to the Himalayas in India.
Importantly, these basins form at the same time as the mountains grow, which means that techniques to work out the age of rock formations can be used to accurately date when both the basin and the mountains started to form.
This means that understanding the geological history of Svalbard can shed light on when and why Greenland became its own tectonic plate.
The Geology of Svalbard The rock outcrops in western Svalbard are intensely folded and cut by long faults.