Let’s pretend to be the end of Cretaceous, around 66 to 100 million years ago. We have dinosaurs that roam the ground and early bird species that look strange, even though the shark as we know has swimmed in the prehistoric ocean which covers 82% of the earth. Redwood trees and other nonak make their debuts, such as roses and flowering plants, and with they come bees, termites and ants. Most importantly, this is warm, volcanic and humid active in all places with no visible ice layer. Except, according to a group of scientists from UC Santa Barbara, Oregon University and Manitoba University, ice conditions do exist in the South Pole.
“And it’s not just a single valley glacier,” UCSB geologist John Cottle said, “it might be glaciers or large ice layers.” Contrary to our picture which is widely held about the late limestone as “heat everywhere,” he said, there was evidence that polar ice was existed during that period, even at the peak of global greenhouse conditions. Forward quickly to this day. Let’s pretend we are in Antarctica. It was cold, barren, and we stood near a large group of open glass stones along the Transantarctic mountains, adjacent to the Ross ice rack, called the butcher ridge Ignous Complex (BRIC).
“I really heard about these stones when I was a postgraduate student 20 years ago, and they were really strange,” Cottle said. Remote, even with the current Antarctic exploration standard, BRIC is unusual because the composition and formation of rocks is not as usual from the rock formation nearby, with, among others, a large number of glasses and multiple changes that show physical, chemical or significant environmental events Occurs with significant significant events carried out by significant significant, significant chemical, chemical or environmental events that change their mineral composition.
Cottle had the opportunity to finally taste BRIC in this new expedition, and in the process of analyzing how it was formed, he and his team found “large amounts of water.””So, you have very hot stones that interact with water, and when they are cold, put it in the glass,” he said. “If you look at the composition, then you can tell something about where the water comes from. It can be as a hydroxyl, which tells you that it might come from magma, or it can be molecular, which means it might be external.”
What they expect to be seen is that the changes in the stone are caused by water that is already in magma when cooled. What they found was a record of the climate process that was considered not there at that time.
In their spectroscopy analysis from the sample, the researchers determined that while some of the water came from magma when he rose to the top of the earth’s interior, when the liquid rock cools into the glass right below the earth’s surface, it also includes groundwater. “We determine that most of the water on these rocks was reduced externally,” Cottle said. “We then measure the composition of oxygen and hydrogen isotopes from water and is very suitable with the composition of snow and Antarctic ice.”
Perform argon-argon geocronology To lock their results, Cottle and Team also do argon-argon geocronology for now rocks and changes. “The problem is, these stones are Jurassic, so around 183 million years,” he said. “So when you measure changes, what you don’t know is when it happens.” They are able to restore the age of stones (jurassic), but also find a younger age (Cretaceous). “So when these stones cool and change,” he continued, “it also rearranges argon isotopes, and you can match the age of change in the composition of change.”
There are other similar volcanic rocks about 700 km north of BRIC which also has the age of Cretaceous changes, showing that polar glaciation may be regionally extensive in Antarctica during that time. “What we want to do is go to other places in Antarctica and see if we can determine the scale of glasiation, if we restore the same results that we have found,” he said.
Finding evidence of a large layer of ice originating from limestone may not change our general picture of the hot and humid earth at that time, Cottle said, “But we must think of Cretaceous and Antarctica which is very different from what we are doing now.” The study in this study was also conducted by Demian A. Nelson (First Author) UCSB, Ilya N. Bindeman at the University of Oregon and Alfredo Camacho at the University of Manitoba. (Ani)