Rajdeep Dasgupta

Associate Professor

image of Dr. Rajdeep Dasgupta

Department of Earth Science, MS-126
Rice University
6100 Main Street
Houston, TX 77005
 
Phone:+1-713-348-2664 (office)
+1-713-348-2144 (lab)
Fax:+1-713-348-5214
E-mail: Rajdeep.Dasgupta@rice.edu
Office: 223 Keith-Wiess Geology Labs

ExPeRT Group Web Page
Personal Web Page

Research Areas

Petrology, Experimental Petrology, Igneous Processes, Planetary Differentiation, Core-mantle exchange, Evolution of metallic cores in planetary bodies, Deep carbon cycle, Deep sulfur cycle in terrestrial planets, Subduction zone processes and volatile cycling, Intraplate volcanism, Mantle heterogeneity, Magmatism in other terrestrial planets such as Mars and Venus

 

Deep cycles of volatiles in the modern Earth

The Earth is unique among the terrestrial planets in our solar system in having a fluid envelope comprising water (H2O), carbon dioxide (CO2), and other volatiles that fosters life. Over million to billion years this is maintained by exchange of volatiles and fluids between the Earth"s interior and the exosphere. My research, over the last few years, provided new insight into partial melting processes of the Earth's upper mantle lithologies in the presence of CO2 and the impact of CO2-induced incipient melting on the geophysical and geochemical properties of the mantle. But still a lot of work remains to be done to constrain the role of mixed C-O-H volatiles on magma genesis and to understand the interplay of redox processes and volatile speciation on the conditions and extent of mantle melting. Our most recent efforts are constraining the efficiency of carbon and water recycling through subduction, devolatilization, and melting of ocean-floor sediments and the solubility of CO2 in hydrous sediment partial melts at sub-arc depths.

While a lot of attentions are given to fully understand the global carbon and water cycle, deep storage and cycles of sulfur have received far less concerted efforts. Thus another new direction that I have started to work on is the petrology of global sulfur cycle. A key question is the efficiency of sulfur transfer from subducting slab to the mantle wedge and the partitioning of sulfur between various phases such as fluids, silicate melts, and mineral sulfides or sulfates and the redox state of sulfur at different tectono-magmatic settings. At present, we are investigating the behavior of basalt hosted sulfides during subduction, dehydration, and melting at a range of oxygen fugacity relevant for the shallow upper mantle. We are demonstrating that mineral sulfide remains abundantly stable during fluid-present melting of subducting ocean crust and hydrous fluid is the key vector to mobilize sulfur from the sulfide-saturated crust to the mantle wedge.

Compositional heterogeneities in the Earth's mantle and generation of oceanic basalts

Basalts from intra plate ocean islands provide a window to the Earth's convecting mantle. One of my long-standing interests is to constrain the mineralogic, lithologic, and volatile heterogeneities present in the Earth's mantle by reproducing the chemistry of the primary basalts through laboratory experiments. I combine both experimental and natural observations to decipher the possible nature of intraplate basalt source regions in general and those for ocean island basalts in particular. Active research topics in this theme include partial melting behavior of various mantle lithologies (with or without volatiles) aimed at petrogenesis of various flavors of basalts, mantle hybridization via melt-rock reaction and the role of melt-rock reaction and other reactive processes on the generation of erupted basalts.

How are the fluids and volatiles inherited in a young Earth? - Magma ocean volatile cycle

A key question related to the volatile-budget of the modern Earth is how it changed through time. Did the Earth acquire the volatiles and achieve their present distribution between the exosphere and the interior at the time of birth, or is the present day budget (including ocean and atmosphere) shaped by later processes, such as late addition of materials (e.g., meteorites, comets)? My recent efforts are constraining the volatile element partitioning and solubility in Earth materials during the early differentiation such as at the 'Magma Ocean' stage (raining metal droplets in largely molten silicates). We are quantifying the importance of Earth's metallic core as a reservoir to sequester various volatiles and how the young Earth might have observed very different inventory of volatiles. This new research brings together laboratory experiments and thermal and geochemical models to help constrain the contributions of ongoing versus early differentiation on the volatile and fluid inventory of the Earth.

Differentiation and volatile evolution of other terrestrial planets

As far as understanding the early evolution of terrestrial volatiles goes, there are lessons to be learnt from similar evolution in other terrestrial planetary bodies, such as Mars, the Moon, Venus, and Mercury. We do not know why these planets have drastically different atmosphere. Is this owing to accretion from vastly different compositions, or is this owing to the difference in conditions of early evolution (e.g., thermal and oxidation state and depth of core-mantle separation) that caused very different fractionation of fluids between the interior and the exosphere? Our goal is to compare and contrast the volatiles and fluids evolution of various terrestrial planets through time.

In relation to this, we recently constrained the thermal vigor of magma generation through the geologic history of the red planet. We demonstrated that the thermal state of Martian mantle is hotter than previously thought and hence mantle melting commences at deeper depths. Motivated by the possibility that Martian basalts may be rich in halogens, we also constrained the effect of fluorine and chlorine on the stability of model Martian magmas. To build on these, we are now looking at the efficiency of sulfur degassing aided by eruption of anhydrous or hydrous basalts relevant for Mars. The aim is to constrain the carrying capacity of sulfur in model Martian basalts and to test whether sulfur-bearing species could have been responsible for creating Martian greenhouse in the early history of Mars.

Teaching Areas

Petrology, High temperature geochemistry, Materials characterization

 

Selected Publications

Refereed Articles

Buono, A., Dasgupta, R., Lee, C-T. A. & Walker, D. (2013). Siderophile element partitioning between cohenite and liquid in Fe-Ni-S-C systems and implications for geochemistry of planetary cores and mantles. Geochimica et Cosmochimica Acta 120, 239-250.

Dasgupta, R. (2013). Ingassing, storage, and outgassing of terrestrial carbon through geologic time. Reviews in Mineralogy and Geochemistry 75, 183-229. doi:10.2138/rmg.2013.75.7

Dasgupta, R., Chi, H., Shimizu, N., *Buono, A. & Walker, D. (2013). Carbon solution and partitioning between metallic and silicate melts in a shallow magma ocean: implications for the origin and distribution of terrestrial carbon. Geochimica et Cosmochimica Acta 102, 191-202. doi:10.1016/j.gca.2012.10.011

Dasgupta, R., Mallik, A., $Tsuno, K., Withers, A. C., Hirth, G. & Hirschmann, M. M. (2013). Carbon-dioxide-rich silicate melt in the Earth+s upper mantle. Nature 493, 211-215.

Jégo, S. & Dasgupta, R. (2013). Fluid-present melting of sulfide-bearing ocean-crust: Experimental constraints on the transport of sulfur from slab to mantle wedge. Geochimica et Cosmochimica Acta 110, 106-134.

Filiberto, J., Wood, J., Dasgupta, R., Shimizu, N., Le, L. & Treiman, A. (2012). Effect of fluorine on near-liquidus phase equilibria of an Fe-Mg rich basalt. Chemical Geology 312-313, 118-126. doi:10.1016/j.chemgeo.2012.1004.1015

Lee, C-T. A., Luffi, P., Chin, E. J., Bouchet, R., Dasgupta, R., Morton, D. M., $Le Roux, V., Yin, Q. & Jin, D. (2012). Copper systematics in arc magmas and implications for crust-mantle differentiation. Science 336, 64-68. doi: 10.1126/science.1217313

Lee, C-T. A., Shen, B., Slotnik, B. S., Liao, K., Dickens, G. R., Yokoyama, Y., Lenardic, A., Dasgupta, R., Jellinek, M., Lackey, J., Schneider, T. & Tice, M. M. (in press). Continent-island arc fluctuations, growth of crustal carbonates, and long-term climate change. Geosphere 9, doi:10.1130/GES00822.1

Mallik, A. & Dasgupta, R. (2012). Reaction between MORB-eclogite derived melts and fertile peridotite and generation of ocean island basalts. Earth and Planetary Science Letters 329-330, 97-108. doi:10.1016/j.epsl.2012.02.007

Tsuno, K. & Dasgupta, R. (2012). The effect of carbonates on near-solidus melting of pelite at 3 GPa: relative efficiency of H2O and CO2 subduction. Earth and Planetary Science Letters 319-320, 185-196. doi:10.1016/j.epsl.2011.12.007

Tsuno, K., Dasgupta, R., Danielson, L. & Righter, K. (2012). Flux of carbonate melt from deeply subducted pelitic sediments - geophysical and geochemical implications for the source of Central American volcanic arc. Geophysical Research Letters 39, L16307. doi:10.1029/2012GL052606

Filiberto, J. & Dasgupta, R. (2011). Fe2+-Mg partitioning between olivine and basaltic melts: applications to genesis of olivine-phyric shergottites and conditions of melting in the Martian interior. Earth and Planetary Science Letters 304, 527-537. doi:10.1016/j.epsl.2011.02.029

Le Roux, V., Dasgupta, R. & Lee, C-T. A. (2011). Mineralogic heterogeneities in the Earth"s mantle: constraints from Mn, Co, Ni, and Zn partitioning during partial melting. Earth and Planetary Science Letters 307, 395-408. doi:10.1016/j.epsl.2011.05.014

Sanloup, C., van Westrenen, W., Dasgupta, R., Maynard-Casely, H. & Perrillat, J-P. (2011). Compressibility change in molten iron-rich metal at high pressure and models of core formation. Earth and Planetary Science Letters 306, 118-122. doi: 10.1016/j.epsl.2011.03.039

Tsuno, K. & Dasgupta, R. (2011). Melting phase relation of nominally anhydrous, carbonated pelitic-eclogite at 2.5-3.0 GPa and deep cycling of sedimentary carbon. Contributions to Mineralogy and Petrology 161, 743-763. doi:10.1007/s00410-010-0560-9

Lee, C-T. A., Luffi, P., Höink, T., Li, J., Dasgupta, R. & Hernlund, J. (2010). Upside-down differentiation and generation of a "primordial" lower mantle. Nature 463, 930-933. doi:10.1038/nature08824

Lee, C-T. A., Luffi, P., Le Roux, V., Dasgupta, R., Albaréde, F. & Leeman, W. P. (2010). The redox state of arc mantle using Zn/Fe systematics. Nature 468, 681-685. doi:10.1038/nature09617

Dasgupta, R., Buono, A., Whelan, G. & Walker, D. (2009). High-pressure melting relations in Fe-C-S systems: implications for formation, evolution, and structure of metallic cores in planetary bodies. Geochimica et Cosmochimica Acta 73, 6678-6691. doi:10.1016/j.gca.2009.08.001

Dasgupta, R., Hirschmann, M. M., McDonough, W. F., Spiegelman, M. & Withers, A. C. (2009). Trace element partitioning between garnet lherzolite and carbonatite at 6.6 and 8.6 GPa with applications to the geochemistry of the mantle and of mantle-derived melts. Chemical Geology 262, 57-77. doi:10.1016/j.chemgeo.2009.02.004

Dasgupta, R., Jackson, M. G. & Lee, C-T. A. (2010). Major element chemistry of ocean island basalts - conditions of mantle melting and heterogeneity of mantle source. Earth and Planetary Science Letters 289, 377-392. doi:10.1016/j.epsl.2009.11.027

Hirschmann, M. M. & Dasgupta, R. (2009). The H/C ratios of Earth"s near-surface and deep reservoirs, and consequences for deep Earth volatile cycles. Chemical Geology 262, 4-16. doi:10.1016/j.chemgeo.2009.02.008

Lord, O. T., Walter, M. J., Dasgupta, R., Walker, D. & Clark, S. M. (2009). Melting in the Fe-C system to 70 GPa. Earth and Planetary Science Letters 284, 157-167. doi:10.1016/j.epsl.2009.04.017

Dasgupta, R. & Hirschmann, M. M. (2007). A modified iterative sandwich method for determination of near-solidus partial melt compositions. II. Application to determination of near-solidus melt compositions of carbonated peridotite. Contributions to Mineralogy and Petrology 154, 647-661. doi:10.1007/s00410-007-0214-8

Dasgupta, R. & Hirschmann, M. M. (2007). Effect of variable carbonate concentration on the solidus of mantle peridotite. American Mineralogist 92, 370-379. doi:10.2138/am.2007.2201

Dasgupta, R. & Hirschmann, M. M. (2006). Melting in the Earth's deep upper mantle caused by carbon dioxide. Nature 440, 659-662. doi:10.1038/nature04612

Dasgupta, R. & Walker, D. (2008). Carbon solubility in core melts in a shallow magma ocean environment and distribution of carbon between the Earth's core and the mantle. Geochimica et Cosmochimica Acta 72, 4627-4641. doi:10.1016/j.gca.2008.06.023

Dasgupta, R., Hirschmann, M. M. & Dellas, N. (2005). The effect of bulk composition on the solidus of carbonated eclogite from partial melting experiments at 3 GPa. Contributions to Mineralogy and Petrology 149, 288-305. doi:10.1007/s00410-004-0649-0

Dasgupta, R., Hirschmann, M. M. & Smith, N. D. (2007). Partial melting experiments of peridotite + CO2 at 3 GPa and genesis of alkalic ocean island basalts. Journal of Petrology 48, 2093-2124. doi:10.1093/petrology/egm053

Dasgupta, R., Hirschmann, M. M. & Smith, N. D. (2007). Water follows carbon: CO2 incites deep silicate melting and dehydration beneath mid-ocean ridges. Geology 35, 135-138. doi:10.1130/G22856A.1

Dasgupta, R., Hirschmann, M. M. & Stalker, K. (2006). Immiscible transition from carbonate-rich to silicate-rich melts in the 3 GPa melting interval of eclogite+CO2 and genesis of silica-undersaturated ocean island lavas. Journal of Petrology 47, 647-671. doi:10.1093/petrology/egi088

Dasgupta, R., Hirschmann, M. M. & Withers, A. C. (2004). Deep global cycling of carbon constrained by the solidus of anhydrous, carbonated eclogite under upper mantle conditions. Earth and Planetary Science Letters 227, 73-85. doi:10.1016/j.epsl.2004.08.004

Hirschmann, M. M. & Dasgupta, R. (2007). A modified iterative sandwich method for determination of near-solidus partial melt compositions. I. Theoretical considerations. Contributions to Mineralogy and Petrology 154, 635-645. doi:10.1007/s00410-007-0213-9

Jackson, M. G. & Dasgupta, R. (2008). Compositions of HIMU, EM1, and EM2 from global trends between radiogenic isotopes and major elements in ocean island basalts. Earth and Planetary Science Letters 276, 175-186. doi:10.1016/j.epsl.2008.09.023

Editorial Positions

Associate Editor, Geochimica et Cosmochimica Acta. Elsevier.

Awards, Prizes, & Fellowships

NSF Faculty Early CAREER Award, National Science Foundation (03/15/2013)

Hisashi Kuno Award, Volcanology, Geochemistry, Petrology section of American Geophysical Union (12/04/2012)

F. W. Clarke Medal, The Geochemical Society (08/14/2011)

Packard Fellowship for Science and Engineering, The David and Lucile Packard Foundation (10/15/2010)

Positions Held

Adjunct Associate Research Scientist, LDEO, Columbia University. (07/08–present)

Visiting Scientist, Lunar and Planetary Institute, Universities Space Research Association. (03/08–present)