Geochemical Evolution of the Mantle
{'Code': '06030107', 'Directorate': {'LongName': 'Directorate For Geosciences'}, 'Division': {'LongName': 'Division Of Earth Sciences'}}
{'SignBlockName': 'John L. Snyder'}
For several years the PI has operated one of the major                          geochemical laboratories in the US, and he has concentrated on                  problems dealing with the origin and evolution of the Earth's                   mantle.  During the previous funding period he and his associates               have: a) determined Sm/Nd ages for sub-continental mantle by                    analysis of silicate inclusions in diamonds: b) delineated a                    golbal isotopic anomaly belt (DUPAL anomaly) lying between the                  equator and 50 degrees S. latitude; cf) delimited the range of                  isotopic signatures for the subcontinental lithosphere by                       analysis of xenoliths and xenolith-bearing baslats from southern                Africa, Turkey, Hungary, Arizona, Poland, Spitzbergen and                       Nunivak; d) refined a model for the refractory incompatible                     element contents of the bulk silicate Earth; e) completed a                     variety of leaching experiments on clinopyroxenes from 2.7 by                   volcanic rocks to demonstrate the trustworthiness of this mineral               for recording initial Sr and Nd isotopic  mantle ratios; f)                     showed that while significant isotopic avriations exist on mantle               scale lengths of 10-50 meters, intra-mineral disequilibria is                   only demonstratabel in mantle xenoliths carrying a metasomatic                  imprint; and g) provided access to state-of-the-art isotopic                    facilities to over 400 scientists from MIT and elsewhere.  During               the five-year tenure of this award, it is proposed to continue                  these same general themes.  Particular effort will be placed on                 the Pb and Os isotopic variations in mantle rocks by direct                     measurement of both ultramafic xenoliths and of smaples from the                Ronda ultramafic massif.
{'FirstName': 'Stanley', 'LastName': 'Hart', 'EmailAddress': 'shart@whoi.edu', 'StartDate': '08/01/1987', 'EndDate': None, 'RoleCode': 'Principal Investigator'}
{'Name': 'Massachusetts Institute of Technology', 'CityName': 'Cambridge', 'ZipCode': '021394301', 'PhoneNumber': '6172531000', 'StreetAddress': '77 MASSACHUSETTS AVE', 'CountryName': 'United States', 'StateName': 'Massachusetts', 'StateCode': 'MA'}
{'Code': '1557', 'Text': 'VOLCANOLOGY & MANTLE GEOCHEMIS'}
{'url': 'https://www.nsf.gov/awardsearch/download?DownloadFileName=1987&All=true', 'xml': '8708372.xml'}