Dr. Zhiyong Xiao
Office Phone: 027-67883048
Office Address: Room 512, Planetary Science Institute
Remote sensing, Planetary surface processes; Earth Impact craters
Structural Geology, Surface Processes on Solar System Bodies
I believe that working hard is the only way to realize oneself. Being serious of any work is the only way to establish oneself. Therefore, I have strict requirement on myself, of course on students as well.
I see students as my collaborator, not apprentices. Being able to archive mutual equality is the only criteria when I make friends and recruit students.
Grants, Fellowships and Awards:
2015/01 – 2017/12: Effect of target volatiles on ejection angles: Indications from the morphology and distribution of secondary craters on Mercury. National Natural Science Foundation of China. Fund: RMB 250,000. Project Number: 41403053. Principle Investigator.
2015/01 – 2017/12: Possibly of impact structures within China mainland remote sensing of potential impact structures. Fundamental Research Funds for the Central Universities, China University of Geosciences (Wuhan). Project Number: CUGL150405. Fund: RMB 300,000. Principle Investigator.
Recruit graduate students
Currently, my researches are focued on the three following subjects.
1) Impact craters on planetary surfaces [NSFC fund]
As the most important geologic process on planetary bodies including the Earth, impact cratering is a beauty to me for its enourmous energic and scale. The physical processes related with impact cratering are amazing and intriguing. Thinking about building the Dabie Mountain has cost how many millions of years, but forming a even larger mountain belt just takes less than 5 minutes by impact cratering! Rock vaporization, melting, strong metamorphism, and deformation all literally occur in less than a blink during impact cratering.
My target is to understand details about the physical processes related with impact cratering. Besides some numerical modelling work using the iSALE hydrocode (http://www.isale-code.de/), most of my researches are related with the morphology and topography of impact craters on various bodies. Since impact velocity, target properties, surface gravity are different on difrerent planetary bodies, the morphological and topography differences of impact craters on different bodies reveal the contribution of different factors in the cratering process. These observations are the ONLY ground truth, which provides direct guildlines for impact modeling and simulations.
Here are some projects that I am now studying:
(1) Controlling factors on ejection angles: secondary craters on continuous secondaries facies typically have very irregular shapes on all planetary bodies. However, many impact craters on Mercury (Xiao et al., 2014) and three impact basins on the Moon (Zhou et al., 2015) have abnormally circular secondaries, such as the ones shown in the image below. What is the reason for the abnormally larger ejection angles? My students and me are now collecting such craters on Mercury and other bodie. We will quantitatively constrain this special morphology and distribution characteristics using ArcMap, USGS ISIS, ENVI, and other image processing softwares. Together with topography, gravity, crustal thickness, reflectance spectra data, we will try to decode the major factor controlling ejection angles.
(2) Formation mechanism of central pits in impact craters: Central pits are frequently observed on Mars and icy satelliates, therefore these topography depressions are attributed to the effect of target/projectile properties on crater formation. However, I recently find impact craters on both Mercury and the Moon have such features (see the image below), and they are not even smaller compared with those on Mars and icy satelliates. What are their formation mechanism? We are studying the morphology and size of such features on different bodies. Together with their background geology, we will try to constrain the fundamental process that has formed the depression.
(3) Emplacement of crater ejecta: impact cratering moblizes a lot materials: The major events during the excavation stage are well constrained (see the image below), but they are still too rough to explain detailed observations (e.g., crater rays). The morphology and size of different crater exterior deposits are the key to understand this process. Studying crater ejecta on different airless bodies such as Mercury, the Moon, and 4Vesta would reveal the emplacement dynamics and sequence of ejecta; considering those on Mars and Venus would further shade light on the interation of atmosphere and high-velocity ejecta.
Students who are interested on the above three projects should have at least one of the following backgrounds: GIS, image processing, hydrocode simulation. MATLAB and USGS ISIS are the required software for the research. I encourage interested students to pursue a Ph. D study on this subject.
2) Possible impact craters in China
Impact cratering and plate tectonics are the two major discoveries in terrestrial geology in the 20th century. Almost every discepline of Earth sciences is eventually related with regional or global plate tectonics. The importance of impact cratering in Earth evolution, however, has not been widely appreciated among Earth geologists. Impact cratering as the most important geologic process has demonstrated itself if you have ever taken a look at the Moon during a clear night. The lunar highland has been saturated by craters larger than 100 km in diameter. The Earth has experienced the same record of impact cratering as the Moon, only that way much more craters and much larger craters have formed on the Earth. Think about this, craters >100 km diameters have once covered EVERY corner of the Earth. Thanks to impact cratering, we human beings can actually live on this planet after the dinosaurs were wiped out by a < 100 km diameter crater. However, such scale impact cratering will definetly occur on the Earth again, and it won’t be just once! If the impact point will be at CUG, where can you hide from this?
As an Earth and planetary geologists, I deeply agree on the importance of impact cratering to Earth geology. I am shocked when saw that only 1 of the 189 confirmed impact craters is located at China, and it was only confirmed in the 21st centrury. China do record a complicated geology history so that modification, deformation, and erosion are serious everywhere. But isn’t that a typical phenomea everywhere? Isn’t that the beauty of science?
I am funded by the Fundamental Research Funds for the Central Universities, China University of Geosciences（Wuhan）to study Earth impact craters in China. Right now, we are calibrating the theoretical number of different sized-craters that must have formed in China, and the theoretical number of craters should be remained. We have done several field trips to investigate candidate examples, and a lot interesting findsing are revealed.
Students who are interested on the this project should have at least two of the following backgrounds: petrology, structural geology, GIS. Field trip is needed, and currently we only consider male students for this project. I encourage interested students to pursue a Ph. D study on this subject.
3) Other planetary surface processes
I am aslo deeply engaing in other researches regarding planetary surface processes. The mystery dark spots on Mercury (Xiao et al., 2013, JGR), small graben system and recent igneous intrusion on the Moon (Xiao et al., 2015, Icarus), cooling fractures in impact melt and columnar joints in planetary basalts (Xiao et al., 2014, JGR), crater equilibrium level for Imbrian and Eratosthnian epoches on the Moon (Xiao et al., 2015, JGR) are my current and recent researches. GIS, USGS ISIS, python simulations are required on these subjects.