Plate Tectonics and Earth Modeling

Geology and 21st Century Challenges

• Efforts are being made to create a digital twin of Earth to forecast natural hazards and improve climate models.
• Models of plate tectonics help in reducing the environmental impact of mineral exploration.

Pangaea and Plate Tectonics

• Continents moving around the breakup of Pangaea has been previously animated.
• Models capture mantle convection linked to moving plates, aiding in understanding the deep carbon cycle, planetary habitability, mineral resources and evolutionary biology.
• The Siberian traps volcanism caused a significant mass extinction.

Modeling Australia's Paleo-geography

• New infrastructure and technologies model the paleo-geography of Australia at the University of Sydney
• Mountains in eastern Australia uplift, subside, and collapse in the model.
• The Eromanga Sea appears and disappears.
• These models are fundamental for capturing and testing sea level curve models.
• A chart shows that 450 million years ago, sea level may have been 100-400 meters higher than present.

Coastline Models

• Models for the last thirty thousand years show coastlines moving rapidly due to Milankovic orbital cycles.
• Dynamic coastlines show migrations across Asia into Australia
• Current research looks at reef systems on the scale of the Great Barrier Reef to understand the rise and fall of reef systems.
• The Great Barrier Reef brings in about $4-5 billion in renewable income from tourism and contributes to basic science and the planetary deep carbon cycle.

21st Century Challenges and Solutions

• There is pressure on natural resources in the 21st century
• Moving toward a circular economy that recycles raw materials is important
• Carbon neutrality by 2050 is discussed, with renewable energy and carbon capture/storage technologies as potential paths.
• Ethical and sustainable mineral extraction is still needed, aligning with the UN's sustainable development goals.

Geological Time Scale

• Geological time is essential to transfer into digital earth models
• The geological record documents the evolution of life, major extinctions, and climate shifts.
• Cenozoic: Age of mammals.
• Mesozoic: Age of birds, reptiles, and dinosaurs.
• Paleozoic: Emergence of early complex life.
• Precambrian: Deep time with very early, simple life.
• The geological time scale is refined and revised with new data

Early Earth

• Earth formed 4.55 billion years ago in the Hadean eon, with a partially molten planet and magma oceans.
• Zircons from Australia are some of the only preserved material from this time.
• Modern plate tectonics is thought to have initiated around 2.5-3 billion years ago
• Early plate tectonics operated differently, more like drip tectonics.
• Earth's interior was hotter, with vigorous convection and high radiogenic heat.

Archean Eon

• The Archean Earth was stabilizing, with less bombardment from meteorites and comets.
• Prokaryotic bacteria emerged, with potential fossils dating back 3.5-3.8 billion years ago.
• Algal colonies of stromatolites were common
• Eukaryotes evolved around 2.7 billion years ago.
• Stromatolites in Shark Bay National Park are living fossils that build up layer by layer.

Early Life

• Processes of layering can be seen in stromatolites and provide evidence for past tidal cycles
• Early life formed in extreme conditions, debated to be in hydrothermal pools or deep oceans.

Extremophile Life and Great Oxygenation Event

• Extremophile life, like that in Grand Prismatic Spring (Yellowstone), exists in different bacterial communities with varied temperatures and chemical compositions.
• Life has a cutoff at 120 degrees Celsius.
• The Archean ended around 2.5 billion years ago, marked by the great oxygenation event about 2.4 billion years ago.
• Photosynthesizing algae and cyanobacteria built up oxygen in the atmosphere.
• Oxygen levels were low at about 0.1% of today's levels.

Proterozoic Eon

• The Proterozoic had an accumulation of atmospheric oxygen, about 1-2% of present day levels
• The first ozone layer protected the Earth from UV radiation occured
• The first reconstructable supercontinent, Rodinia, formed.
• Rodinia was barren, as plants and animals had not yet colonized the land due to insufficient ozone layer protection.

Snowball Earth and Ediacaran Fauna

• The snowball Earth episodes occurred before and after Rodinia, with ice sheets meeting at the equator.
• Volcanism from plate tectonics brought CO2 into the atmosphere, breaking down the "icehouse" climate over millions of years.
• Glacial rocks and drop stones provide evidence of past glaciations.
• The Ediacaran fauna, represented by the Ediacara Hills near Adelaide, showed a unique evolutionary development with complex lifeforms lacking hard parts.
• Dickinsonia (pancake shaped spongy animal)

Paleozoic Era

• The Paleozoic began 540 million years ago and marked the evolution of complex life with hard skeletons and ended with the greatest mass extinction ever.
• The Cambrian explosion marked the start of the Paleozoic
• Development of hard parts of skeletons drastically changed the dynamics of predator and prey.
• The Burgess Shale in Canada preserved the incredible variety of lifeforms, with about 14% having hard parts.
• Tamisiocaris borealis is a Cambrian predator

Cambrian Period

• The Cambrian saw the first trilobites
• The horseshoe crab is another "living fossil"
• Horseshoe crab blood is vital for medical research due to blue blood's clotting agents
• Sea scorpions made temporary land visits

Ordovician and Silurian Periods

• The Ordovician period, around 450 million years ago, marked a huge radiation of life with diverse forms includeing nautiloids and burrowing animals becoming common.
• The Silurian period started with a major mass extinction
• The first primitive land plants and bony fish appeared

Devonian Period

• The the pace of evolution picked up
• The first forests emerged
• Eastern Australia's continental landmass was amalgamating and growing.
• The Devonian had a incredible variety of reefs, but corals were different from modern ones and later went extinct
• Fossils of Devonian reefs can be seen in Yass.

Carboniferous and Permian Periods

• The Carboniferous period, about 320 million years ago, was a warm period with high forest growth, forming much of the coal.
• Oxygen levels peaked at 35%, compared to today's 21%.
• Fossils of large dragonflies (meganeura) with 65cm wingspans existed due to high oxygen content.
• Carboniferous forests turned into coal
• The Permian Period had the amalgamation of the supercontinent Pangaea and ended with the largest mass extinction.
• An estimated 90% of marine life and 70% of terrestrial life became extinct
• The end-Permian extinction was triggered by major flood basalts in Siberia
• CO2 released over 1-2 million years, slower than human-caused CO2 release
• Sedimentary layers are seen from Bulli.

Triassic Period

• After the mass extinction, life innovated and filled niches left by extinct species
• The age of reptiles, dinosaurs, and birds begins
• Pangaea dispersed and broke up
• The first dinosaurs appeared, and magnetic reversals were captured in the sedimentary record
• Triassic was hot and dry around 200-250 million years ago
• Modern corals appeared.

Jurassic and Cretaceous Periods

• Jurassic is a favorite due to Jurassic Park, but still had dinosaurs
• First primitive birds
• Jurassic Park was misnamed because T-Rex only lived at the very end of the Cretaceous about sixty seven million years ago
• Dinosaurs remained in the Jurassic period and Cretaceous, until ecosystem destabilization
• Deccan traps and Reunion plume erupted huge amounts of CO2, a culprit for their end
• 65 million years ago, a major bolide impact on the Yucatan Peninsula created a nuclear winter.

Cenozoic Era

• The bolide impact caused extinction of the food chain and dinosaurs.
• Life innovated, and mammals dominated the Cenozoic.
• There was a drying and cooling trend related to tectonics and closure of the Tethyan Ocean gateway.
• Closing the equatorial Tethyan Ocean and opening the Southern Ocean gateway was important
• Early hominids appeared in Africa in the last few million years.
• The frantic pace of evolution in the last 540 million years, the Phanerozoic timeframe, from simple to complex multicellular life.
• Cambrian explosion marked the onset of complex modern life.