Cosmogenic surface exposure dating

20 May

Researchers suggested that the accumulation of these isotopes within a rock surface could be used to establish how long that surface was exposed to the atmosphere.

Assuming a constant rate of production, the number of atoms of Be-10 and Al-26 that accumulate in a rock surface will be proportional to the length of time the rocks were exposed to cosmic ray bombardment and the respective rates of radioactive decay for each isotope.

Earth is constantly bombarded with primary cosmic rays, high energy charged particles — mostly protons and alpha particles.

These particles interact with atoms in atmospheric gases, producing a cascade of secondary particles that may in turn interact and reduce their energies in many reactions as they pass through the atmosphere.

Cosmogenic nuclides are rare nuclides that form in surface rocks because of bombardment by high-energy cosmic rays[3].

Cosmogenic isotopes are created when elements in the atmosphere or earth are bombarded by high energy particles (-mesons and protons, collectively known as cosmic rays) that penetrate into the atmosphere from outer space.

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It is an excellent way of directly dating glaciated regions.Surface exposure dating is a collection of geochronological techniques for estimating the length of time that a rock has been exposed at or near Earth's surface.Surface exposure dating is used to date glacial advances and retreats, erosion history, lava flows, meteorite impacts, rock slides, fault scarps, and other geological events.Surface exposure age dating requires intensive chemistry.Our samples are now pre-treated at the University of Canterbury.