STRATA OF PILBARA

Explanation by Prof Martin Van Kranendonk, Professor of Geology, Director, Australian Centre for Astrobiology

North Pole Dome drilling, Western Australia, 2019

Strata of Pilbara – Core #410
„Black chert. This dark, extremely hard rock is an enigma – what does it represent, how did it become so hard and rich in silica? Was it originally a softer sediment that was hardened by mineralised fluids, or was it actually a hard rock to start with and came from the depths of the crust. What secrets will we find when we put it under the microscope and when we analyse its chemistry? Will it hold some useful information about our planet when it was very young?“

Strata of Pilbara – Core #426
„These very unusual, swirly patterns were the prime reason for our undertaking the scientific drilling program and, in fact, reflect on a very exciting moment in my life! We were searching for the fossilised deposits from ancient hot springs, 3.5 billion years old, which we had seen on the surface, where they are weathered and altered by exposure to oxygen. But we had never seen the in fresh rocks from beneath the effects of surficial oxidation. Here, with this sample, when it popped out from the drilling tube, we had found them! We are hoping these samples will tell us about how life on Earth got started and what conditions were like on a very young Earth.“

Strata of Pilbara – Core #414
„These swirly green layers are ancient deposits of sand, likely from a stream on the Earth’s surface 3.5 billion years ago. They may tell us what the surrounding surface was like, and the atmosphere and perhaps even whether there were meteorites bombarding the surface.“

Strata of Pilbara – Core #417
„This gorgeous sample is the other main reason we undertook the drilling project – to search for signs of ancient life in these hot spring and sandy deposits. Here we see a row of bulbous, layered structures that rise up from a flat surface. These are structures made by living communities of micro-organisms, which we call stromatolites. They are some of the oldest evidence for life on the planet and are made of the mineral pyrite, which was precipitated from iron-rich lake water by the microbes, probably as the result of sulphate reduction.“