protactinium-ionium age method

A method of calculating the ages of deep-sea sediments formed during the last 150,000 years from measurements of the ratio of protactinium-231 to ionium (thorium-230), based on the gradual change of this ratio over time because of the difference in half-lives.

Related terms:

• slice method
• corona method
• three-point method
• Thiessen polygon method
• hyperbolic distribution method
• parcel method
• porphyroclast aspect ratio method
• uranium age
• age ratio
• induction method