Lightning may have produced an important source of food for the planet’s first microbes: a rare form of phosphorus, according to a study published in Nature Geoscience.Researchers examined 10 chunks of sand melted together by lightning, formations called fulgurites, and found a high concentration of the minerals phosphite and hypophosphite in five of them. The soil surrounding the fulgurites contained only phosphate, not phosphites, suggesting that the lightning itself gave rise to phosphites.
“When lightning strikes, it acts like a mini smelter, and the organic molecules strip off oxygen from the phosphorus” [Scientific American], says study coauthor Matthew Pasek.The fact that microbes still have the machinery to digest these phosphites has long puzzled scientists, since phosphites are much rarer than other forms of phosphorus. Lightning forges about two to three tons of the [phosphite] compounds each year, barely enough for life to take notice. But modern bacteria still retain the ability to eat phosphite, which may be a holdover from antiquity [Discovery News].
(more…)
A European spacecraft that has been peering through the thick, roiling clouds of Venus for the past three years has found further evidence that the inhospitable planet once had oceans, volcanoes, and a system of plate tectonics similar to those at work on Earth. The Venus Express has mapped the planet’s southern hemisphere using infrared imaging, and found heat variations in the surface rocks, which allows researchers to speculate on the chemical composition of those rocks. Different surfaces radiate different amounts of heat at infrared wavelengths due to a material characteristic known as emissivity, which varies in different materials [SPACE.com].
In certain highland areas, researchers detected cooler patches of rock whose thermal signatures resemble those of granites on Earth. On our own planet, granites are made during the process of rock recycling that goes on at the edges of the great geologic plates that cover the Earth. At the boundaries of these plates, ancient rock is pulled deep into the planet, reworked with water and then re-surfaced at volcanoes. Critically, then, if there is granite on Venus, there must also have been an ocean and a process of plate movement in the past [BBC News].
(more…)
Tiny crystals found in an Australian rock formation may be the key to understanding what earth looked like in its very earliest days, researchers say; a new study of 4-billion-year-old crystals seems to indicate that our planet already had plate tectonics, and may have looked much like it does today. Little is known about the so-called Hadean or the ‘hell-like’ period of Earth’s history, which spans the time from Earth’s formation 4.6 billion years ago until about 3.8 billion years ago. The best geological clues of this era come from hard minerals called zircons, which have survived weathering and can be found within younger rocks [Nature News].
An analysis of the Australian rocks showed that minerals trapped within the zircon crystals had formed at a lower temperature and higher pressure than expected for crust of that age…. This suggests that the crystals had been formed in a subduction zone, where one rocky tectonic plate plunges beneath another, showing that plate tectonics was up and running at this time [New Scientist]. Researchers theorized that the minerals formed at lower temperatures because they were saturated in water, a finding inconsistent with earlier images of the earth as covered in boiling seas of magma; subduction zones are cooler than other deeply buried rock formations because they’re chilled by ocean water.
(more…)
A slab of bedrock on the shore of Canada’s Hudson Bay may be the oldest piece of the planet ever discovered: Researchers believe the rock is 4.28 billion years old, which would mean that it formed less than 300 million years after the earth itself came together. However, geologists say that considerable controversy remains over the research team’s method of dating the rocks.
Study author Richard Carlson says that if his team is right about the rock’s extraordinary old age, it will change conceptions of how the planet developed its current form, with solid tectonic plates and a stable crust. Says Carlson: “These rocks paint this picture of an early earth that looked pretty much like the modern earth.” … [T]he existence of solid rock 4.28 billion years ago would run counter to the traditional image of the young earth as a roiling cauldron of magma oceans, a view that is falling by the wayside among researchers as more geological data is unearthed [The New York Times].
(more…)
