Please answer all the following questions correctly since they are related to th
ID: 292358 • Letter: P
Question
Please answer all the following questions correctly since they are related to the graph.
Figure: Graph showing oxygen isotope ratio in planktonic foraminifera shells at ODP site 677 (tropical Pacific Ocean)
1- The figure shows the foraminiferal oxygen isotope record for ODP Site 677, in the tropical Pacific Ocean. What is the range through which ?18O values fluctaute between 2 million and 1 million years ago? Between 500 kyr ago and the present?
2- What does your answer to #1 indicate about the magnitude of the change in global ice volume during these two intervals?
3- What is the frueqency of the large amplitudes cycles between 0 and 500 kyr? What are the dominant orbital rhythms controlling these samples? Does this change before 1 million years ago?
0 500 1000 1500 2000 2500 0.5 -1 2 -2 2.5 Age (kyr)Explanation / Answer
1. Fluctuation of oxygen isotope ratio values between 2 million and 1 million is (maxima(-.06)-minimum(-2.15))=1.55
and between ages 500kyr and present is -0.35(maximum) - -2.65(minimum) = 2.3
2. between 2 and 1 million it could be said to be increase in o18 isotopic concentration thus increase in global ice
where as in 500 kyr and present there is a decrease in O18 isotopic concentration suggesting decrease in global ice
3.five large amplituede cycle in .5 million thus frequency is no of cycles/time in years
f=5/0.5=10.
no, it is almost same the frequency changes after after 1million year