Which older mesopotamian civilization did the chaldeans admire and study?

The correct answer is - Sumerian culture.

The Sumerian culture is the first Mesopotamian culture, and it was a culture much ahead of its time and much more developed than the other civilizations. The Sumerians discovered lots of things and lied the foundations for lots of sciences, so it is no wander that they have been admired by the other people. The Chaldeans were one of their biggest admirers, and they were especially admiring their achievements in mathematics and astronomy.