Solar System Formation

1. Solar System Formation 4.6 billion years ago Q: From what materials is our solar system made?

2. Long gone Orogens and other topographical elevations are removed - a window into the Earth.

3. Paleomagnetic polar wandering The rocks point to magnetic poles over time - the relative movement of the apparent poles on different plates indicates movement

4. Building blocks Remember these? Meteorites called carbonaceous chondrites The juxtaposition of very high temperature components (chondrules and inclusions made of silicates) and very low temperature components (complex carbon compounds).

5. Segregation Density variation between stable phases in a gravitational field- The Fe alloys head down, the silicates float. Note solidification of silicates with depth. Two types of materials? Taylor, 2005

6. Then and now The dense stuff is at the center. We have an atmosphere made of the light stuff (but not really light stuff). How? Ballentine, Science 296, 2002, 1247-1248

7. Early Earth The Moon shows evidence of heavy bombardment up to 3.8 Ga Undoubtedly, the Earth is being impacted simultaneously – the impacts would make the surface of the Earth unsuitable for liquid water. Life is not likely to arise until frequent impacts cease.

8. Or not… Recent evidence shows that the oldest materials on earth, Jack Hills Zircons, are 4.4 biliion years old. These record crystallization temperatures in the 600-750 ºC range - implying wet magmatic conditions and the possible establishment of the hydrosphere. NASA’s Earth Observatory

9. Hot • But prior to 4.4 Ga, there are a number of problems with the early Earth. • Very hot • Frequent inputs of high kinetic energy • Weak atmosphere • Sunlight reduced at surface • No liquid water at surface (and little fluid water at depth) • No complex organic molecules • All except last are reduced through gravitation and kinetics. The last is trickier although helped by cooling temperatures.

10. ridge The upper mantle has a “depleted” composition. Crust + depleted mantle is roughly that of the lower mantle and chondrites The lanthanides (La-Lu) are also known as the rare earth elements.

11. Continents

12. Cratons

13. North American Structure The shield is the oldest part of the continent Primary continental material - it’s mostly metamorphosed or igneous. Platform - largely the locus of layered sediments. Orogenic belts - mountain building deformation

14. Craton Assembly of the shield and sub-platform over a sequence of time

15. Domains of Life Analyses of DNA make it suggest that all of life on Earth is related back to one single organism. Chemically, we’re all very similar.

16. Figure 24.24 24-515

17. Life chemistry In 1953, Miller and Urey conducted an experiment in which methane, ammonium, hydrogen, and water were subjected to an electrical discharge. After a week, 10-15% of C formed organic compounds, 2% as amino acids. Suggests that a primitive atmosphere could produce life compounds.

18. Secondary steps • Amino acids are a long way from proteins and nucleic acid • The next step is the subject of ongoing investigations. • One current theory: the RNA world • RNA has the ability to copy itself, modify as an enzyme, and bond with amino acids. • Many viruses proliferate with nothing more than RNA and protein (although few think viruses were the first life – too dependant on cellular life)

19. Clay surfaces James Ferris (RPI) has been able to assemble complex polymers (primitive RNA) compounds by activating simpler monomers on the surface of clays. RNA (Ribonucleic acid) is present in all life forms, aids protein encoding, and can carry genetic information.

20. Early life: Cyanobacteria [P] Stromatolites - shallow marine algal mounds from the Cambrian as seen in Lester Park, near Saratoga Springs, NY. The first fossils of bacteria are 3.2 Ga. Cyanobacteria from the Bitter Springs chert of central Australia, a site dating to the Late Proterozoic, about 850 million years old.

21. Meet BIF (Banded Iron Formation) Rock is 2.5 billion years old (found world wide from 3 - 1.8 Ga) Dark: Hematite (Fe2O3) Red: Quartz (with iron) Yellow: Crocidolite (blue asbestosform) The accumulation of iron as seafloor sediments is thought to result from early photosynthesis on the ocean surface under N2 – CO2 rich conditions. A lack of atmospheric O2 permits Fe ions in surface seawater – these bond with O2produced by photosynthesis.

22. Oxygen and complex life

23. Oxygenation of the atmosphere Scientists think that the first organisms (producers) depleted an initially CO2 rich atmosphere, enriching it in oxygen Q: what process may have enriched O2 in the atmosphere? Figure 24.4 24-507

24. Extreme The existence of life deep in the ocean at extreme conditions has led many to conclude that early life may have used the heat of the Earth for energy We are still a long way from understanding how life chemistry came together initially.

25. It’s life, as we know it Cellular life The oldest fossils – not much to look at, but appears to be a filamentous bacteria from 3.5 billion years ago. http://projects.edtech.sandi.net/miramesa/Organelles/fossilbact.html

26. Archaea [D] (extremophiles)

27. Changes in ice coverage End of Proterozic evidence suggests a very cold Earth surface. Snowball Earth starts with ice on continents extending into the oceans

28. Sequences There is more or less a global response to sea level (as a function of ice cover). Sedimentary layers show how the water covers inland (transgression) and recedes (regression)

29. North America

30. Sea level Keep in mind that the sea level fluctuation is best recorded by rises (more shelf). The rises are the result of less ice - therefore warmer global systems

31. Making-closing and ocean

32. Geologic Time Scale Oldest humanoid fossil 4.3 Ma Oldest fossil plants 440 Ma Oldest chordates 510 Ma Oldest fossil green algea 530 Ma Oldest shelled invertebrates 570 Ma Oldest animal fossils (Vendian) Oldest fossil fungi 650 Ma Oxygenated atmosphere 1.7 Ga Oldest fossil organism 3.5 Ga Oldest rock 3.9 Ga Q: what is the significance of plants with respect to environment? Figure 20.50 20-424

33. The fossil record not only tells of the development of life, it speaks to the termination of organisms. • Extinction is when a type of organism (species) fails to appear past a certain time horizon in the fossil record, or ceases to exist in modern ecosystems. • Extinctions happen throughout time, but there have been six to seven points in earth history when a significant number of organism types became extinct. • 650, 540, 510, 440, 340, 248, 65 million years • The cause of mass extinctions is not known, but most theories point to global catastrophe • Bolide impacts (likely for the K-T) • Large-scale volcanism • Rapid climate change • Slow magnetic reversals

34. 1.1 Ga Recall the mountain building event we called the Grenville Orogeny. The assembly of the super continent known as Rodinia formed these mountains.

35. Grenville in North America

36. 650 Ma Very little land. However, all of the organisms are likely marine dwelling.

37. Vendian Specialized cells apparently arose by 650 Ma, with the Vendian organisms. They look like casts of soft parts – but not much is known about these critters. Fungi also arise at the same time. Fungi can be monocellular, colonial, or multicellular. The one in the picture (right) is only 360 Ma from the Rhynie Chert, Scotland.

38. Events

39. Paleozoic

40. Cambrian explosion • Starting at 570 and leading to 540 million years ago, life diversified. The number of fossils increases in the rocks, and they organisms have different morphologies. Many of these organisms have some relatives alive today • Segmented arthropods: trilobites • Sponges • Bryozoa • Corals • Brachiopods • The reason is the source of serious scientific debate, but obviously linked to emerging (and possibly stabilized) thermal and chemical conditions in the ocean.

41. 514 Ma

42. Multicellular and skeletal Eukaryotes can be single cellular or multicellular. Specialized cells developed. Some cells in complex organisms can be quite complicated. Sponges (poriphera) are animals Note, sponges, are extensive in the fossil record, beginning 540 Ma – a hard skeleton made of calcite or quartz makes them incredibly durable.

43. 458 Ma

44. Taconic orogeny

45. Iapetus seafloor

46. Early Plants Plants are very close to algae in genetic structure Algae are another organism that has its oldest fossils in the Cambrian. Plants occur much higher in the record – 440 million years ago, and are found in rocks that formed on land. Plants are simple to complex multicellular autotrophs. Key is the development of specialized cells to extract moisture, amino acids, nitrates, phophates, and minerals from soils (roots). Some of the earliest fossils are fern-like in morphology Note: modern land plant height is limited by gravitational constraints of lifting water.

47. Animals are heterotrophs – they need to eat autotrophs to get carbohydrates. Until recently, fossil land animals were found to be all younger than fossil plants However, a 470 Ma fossil of a millipede, discovered in 2004, is now thought to be the oldest land fossil. Either older land autotrophs existed or this millipede stayed close to the water. The conversion from water to land (or vice versa) is a difficult one Most (but not all) aquatic heterotrophs organisms extract oxygen from water*, and autotrophs carbon dioxide from water. Most land heterotrphs extract oxygen from air. Life is largely made of water, and therefore is similar in density. Most organisms are boyant in water (and not in air). Gravity is more of a factor on dry land. *the attempt to extract oxygen from water in organisms that extract it from air is the phenomena known as drowning.

48. 425 Ma

49. Silurian

50. Closing Iapetus Recall that the Taconic orogeny slaps an linear string of volcanoes (an island arc) onto the eastern end of Laurentia (proto-North America). The closure of the Iapetus results in the Acadian orogeny.