It allows any young seafloor surveyed to be dated without any destructive sampling. The data obtained not only identified the position of the mid-ocean ridge in the area for the first time, but also revealed that despite there being 18 lava flows in the area in the last few thousand years, the volume of the eruptions was not enough to build the amount of new crust required by the plate separation.
Applied for the first time during research cruise POS436 aboard the German research vessel Poseidon to a section of the Mid-Atlantic Ridge north of Iceland called the North Kolbeinsey Ridge, the scientists were able to prove that there must have been repeated phases of volcanic eruption on a timescale of at least tens of thousands of years. “In fact, over the last 8,000 years we see at least 5,000 years with no volcanic eruptions whatsoever and what we do see the rest of the time isn’t nearly enough.
While we have some good estimates and hypotheses, the frequency and size of these eruptions, which are occurring under the oceans globally, is basically unproven,” said Dr. However, using a new method developed at GEOMAR the scientists have been able to simultaneously survey and date young lava flows on a segment of the Mid-Atlantic Ridge north of Iceland and show that large volume, episodic eruptions must be occurring.
The new method, developed using the Autonomous Underwater Vehicle (AUV) ABYSS at GEOMAR utilizes acoustic data of the seafloor collected by the robot alongside records from sediment cores collected in the vicinity.
Where excess argon is a problem, accurate, reliable dates typically can be obtained using harlequin2, 2001.
Geochronology and Thermochronology by the 40Ar/39Ar Method.
The problem is not universal, as the majority of minerals and rocks dated by K-Ar do not contain the excess argon.
As this lava flow is considered to be the youngest one of seven post-Jala lava flows, the age also defines a period of inactivity of Ceboruco volcano of about 730–860 yr before the historic 1870 eruption.
Future volcanic hazard analysis will have to take into account this result.
The Icelandic volcanic eruptions of Eyjafallajokull and Bardabunga have produced images of the volcanic activity on the island in recent years.
As Iceland is part of the Mid-Atlantic Ridge these eruptions also strikingly demonstrate how new material for the Earth’s crust is permanently produced at mid-ocean ridges.