Rice University | 2016 Aug 05
Element ratios suggest Earth collided with Mercury-like planet
[img3="Schematic depiction of proto Earth’s merger with a potentially Mercury-like planetary embryo, a scenario supported by new high pressure-temperature experiments at Rice University. Magma ocean processes could lead planetary embryos to develop silicon- or sulfur-rich metallic cores and carbon-rich outer layers. If Earth merged with such a planet early in its history, it could explain how Earth acquired its carbon and sulfur. (Courtesy: Rajdeep Dasgupta)"]http://news.rice.edu/files/2016/08/0822 ... eqd9df.jpg[/img3][hr][/hr]Research by Rice University Earth scientists suggests that virtually all of Earth’s life-giving carbon could have come from a collision about 4.4 billion years ago between Earth and an embryonic planet similar to Mercury.
In a new study this week in Nature Geoscience, Rice petrologist Rajdeep Dasgupta and colleagues offer a new answer to a long-debated geological question: How did carbon-based life develop on Earth, given that most of the planet’s carbon should have either boiled away in the planet’s earliest days or become locked in Earth’s core? ...
Earth’s core, which is mostly iron, makes up about one-third of the planet’s mass. Earth’s silicate mantle accounts for the other two-thirds and extends more than 1,500 miles below Earth’s surface. Earth’s crust and atmosphere are so thin that they account for less than 1 percent of the planet’s mass. The mantle, atmosphere and crust constantly exchange elements, including the volatile elements needed for life.
If Earth’s initial allotment of carbon boiled away into space or got stuck in the core, where did the carbon in the mantle and biosphere come from? ...
Carbon and sulfur budget of the silicate Earth explained by accretion of differentiated planetary embryos - Yuan Li et al
- Nature Geoscience (online 05 Sep 2016) DOI: 10.1038/ngeo2801