The Pilbara Craton is an ancient and stable part of the Earth's crust located in the Pilbara region of Western Australia.
It is one of only two well-preserved Archaean crusts (3.8–2.7 billion years old) found on Earth, along with the Kaapvaal Craton in South Africa. The youngest rocks in the area assigned to the Pilbara Craton are 1.7 billion years old. Both regions may have once been part of the Vaalbara supercontinent or the Ur continent.
There are two different systems used to classify the area into smaller geographical regions.
Geology
The most important part of the Pilbara Craton for studying Earth's early crust is called the Eastern Pilbara Craton. This area still shows rocks from Earth's crust that are up to 3.8 billion years old. It also has granite-like rock formations and greenstone belts that are about 3.5 to 3.2 billion years old. In 2007, scientists reviewed the geology of the Pilbara Craton and separated a thick layer of alternating clastic or chemical sedimentary rocks and volcanic rocks. These rocks form the Fortescue, Hamersley, and Turee Creek basins, which are usually dated from 2.78 to 2.42 billion years old. A younger volcano-sedimentary basin called the Ashburton Basin is dated from 2.21 to 1.79 billion years ago. A surface area between the Fortescue and Hamersley basins is even younger, less than 1.7 billion years old, as are the surrounding surface rocks near the Pilbara Craton. To the east and south of the Eastern Pilbara Craton, there are large areas of very old rocks. These rocks are limited to the traditional area of the Pilbara Craton, which is believed to be mostly underground for more than half its area.
In 2025, scientists found shatter cones near Marble Bar, confirming the 3.47 billion-year-old North Pole Dome as the oldest known impact structure (a remnant of an impact crater) in the world.
The Pilbara region has large deposits of high-quality iron ore. It also contains valuable minerals such as gold, silver, copper, nickel, lead, zinc, molybdenum, vanadium, and fluorite that can be mined.
Evidence of earliest life
Evidence of the earliest known life on land may have been found in 3.48-billion-year-old geyserite and other related mineral deposits, often found near hot springs and geysers, uncovered in the Dresser Formation in the Pilbara Craton. Biogenic sedimentary structures, such as microbialites like stromatolites and MISS, were found in tidal, lagoonal, and subtidal coastal areas. These environments can be understood by studying the layers of rock in the Dresser Formation. The rocks in the Dresser Formation show signs of haematite changes that might have been influenced by microorganisms.
The earliest direct evidence of life on Earth may be fossils of microorganisms preserved in 3.465-billion-year-old Australian Apex chert rocks. However, scientists have debated whether these structures were formed by living organisms. Initially, 11 types of microorganisms were identified in a deposit thought to be near a river because of features like rounded and sorted grains. Later studies using field mapping and petrogenetic analysis showed that the setting where these microfossils were found is actually hydrothermal, and this is widely accepted. Many alternative non-living explanations have been proposed for the filamentous structures, including carbon-rich layers around quartz spheres and rhombs, witherite self-assembled shapes, and haematite-filled cracks. The carbon in the filaments has been studied using Raman spectroscopy, but results have been mixed, making this method unreliable for proving biological origins alone. The strongest argument to date comes from high-resolution electron microscopy, such as scanning and transmission electron microscopy. This study found that the tiny shapes of the filaments and the distribution of carbon do not match biological origins. Instead, hydrothermal conditions likely caused changes like heating, adding water, and peeling potassium micas, with barium, iron, and carbonate later attaching to them.
Carbon-rich structures that seem to be of biological origin have also been found in the 3.47-billion-year-old Mount Ada Basalt, a rock layer slightly older than the Apex chert. However, the biological origin of these structures has also been questioned, with some studies suggesting non-living processes may explain their formation.
Other potential signs of life from the Precambrian era have been found in the northeastern Pilbara Craton, including carbon-rich microfossils.