Edward Ching-Te Chao(Triệu Cảnh đức;November 30, 1919 – February 3, 2008) was one of the founders of the field ofimpact metamorphism,the study of the effects ofmeteoriteimpacts on the Earth's crust.
Edward C.T. Chao | |
|---|---|
| Born | November 30, 1919 |
| Died | February 3, 2008(aged 88) |
| Alma mater | University of Chicago |
| Known for | impactmetamorphism |
| Awards | Barringer Medal(1992) |
| Scientific career | |
| Fields | Geology |
| Institutions | U.S. Geological Survey |
Born inSuzhou,China,he was best known for discovering two high-pressure forms ofsilicain nature:coesiteandstishovite.
Early life
editChao was born inSuzhou,China.He was the son of theologianT. C. Chao.[1]
Career
editChao came to theUnited Statesin 1945 to teach Chinese to American troops. He then attended theUniversity of Chicagoand was granted a PhD in geology in 1948. In 1949, he was employed by theUnited States Geological Survey(USGS), where he spent his entire professional career until retiring in 1994.
Scientific contributions
editChao worked on a variety of topics over the course of his USGS career, includingengineering geology,economic geology,andcoalpetrology.However, he was best known for his work onimpactgeologyandtektites.Shortly after he began work on tektites in 1960, Chao was given a sample ofsandstonefrom the vicinity ofMeteor Crater,Arizona.From this material, he was able to isolate an unusualmineralwith highrefractive index,which he showed to be a high-pressurepolymorphofsilicon dioxide.He named the new mineralcoesitein honor of the scientist who had synthesized the same phase in the laboratory seven years earlier.[2][3]Several years later, Chao found a second high-pressure polymorph of silica in these rocks. It, too, had been previously synthesized in laboratory studies, but was not known to occur in nature. He named this mineralstishovitein honor of the person who had first made it, Russian physicist,Sergei Stishov.[4]Coesite and stishovite became known as hallmarks ofimpact craterevents, which were essentially the only natural processes that produced high enoughpressuresto transform ordinaryquartzinto both of thesedenseminerals. Chao went on to find coesite and stishovite in rocks from theRies CraterinBavaria,Germany,establishing that this structure was also produced by impact cratering.
Chao made many pioneering studies on tektites, and discovered the occurrence ofiron-nickelmetal in specimens from thePhilippines.This helped establish that tektites were produced inmeteoriteimpacts. He also recognized that tektites showed evidence for passage through Earth's atmosphere, which led him to the conclusion that the impacts responsible for tektites occurred on theMoon,a view that is no longer widely held among scientists.
His work onMoon rocksincluded being a member of preliminary examination teams and a principal investigator during theApollo11-17 research programs.
Publications
edit
- Comparative water-quality assessment of the Hai He River basin in the People's Republic of China and three similar basins in the United StatesArchived2010-07-03 at theWayback MachineU.S. Geological SurveyProfessional Paper No. 1647 (2001)
- Comparison of the Cretaceous-Tertiary boundary impact events and the 0.77-Ma Australasian tektite event; relevance to mass extinctionArchived2009-05-08 at theWayback MachineU.S. Geological SurveyBulletin No. 2050 (1993)
- Allocation of subsamples of Apollo 17 lunar rocks from the boulder at station 7, for study by the International ConsortiumU.S. Geological SurveyOpen-File Report No. 78-511 (1978)
- Merumite; a complex assemblage of chromium minerals from Guyana[permanent dead link]U.S. Geological SurveyProfessional Paper No. 887 (1976)
Honors
editChao received theJohn Price Wetherill Medalfrom theFranklin Instituteand, in 1992, theBarringer Medalfrom theMeteoritical Societyfor his work in impact geology. He was a recipient of the Alexander von Humboldt Foundation Senior U.S. Scientist Award, and had an asteroid named for him,3906 Chao.The mineralchaoite,an impact-produced form ofcarbondiscovered at theRies Crater,was also named in his honor.
References
edit- ^Glüer, Winfried (2017)."Zwischen Scheitern und Hoffnung. T.C. Chao – Die letzten Jahre".In Hoster, Barbara; Kuhlmann, Dirk; Wesolowski, Zbigniew (eds.).In Difer Hoffnung Verwurzelt.Taylor and Francis. p. 413.ISBN9781351672788.
- ^E. C. T. Chao, E. M. Shoemaker, and B. M. Madsen (1960) First Natural Occurrence of Coesite. Science 132, no. 3421, pp. 220–222[1]
- ^Schaber G.G. (2005) The U.S. Geological Survey, Branch of Astrogeology—A Chronology of Activities from Conception through the End of Project Apollo (1960-1973). USGS Open-file report 2005-1190[2]
- ^Chao, E.C.T. et al. (1962), Stishovite, a very high pressure new mineral from Meteor Crater, AZ, Journal of Geophysical Research: 67: 419–421.