My primary research interest lies in understanding petrological and tectonic processes operating in continental and oceanic crusts. To investigate these processes, I integrate field- and lab-based petrological and structural analyses with mineral chemistry, thermobarometry, phase equilibrium modeling, geochronology and geochemistry. Specifically, my current and previous research fall into the following directions.

1. Formation, differentiation and exhumation of orogenic lower crust

The formation, differentiation and exhumation of lower continental crust remains an enigmatic area to investigate. My group and my collaborators are currently investigating orogenic lower crust in Phanerozoic and Precambrian orogens, trying to understand 1) how did the lower crust form, differentiate and exhume, and 2) the timescale and rate of these processes.

Example publications:

  • Cao, W., Massonne, H.-J. and Liang, X., 2021. Partial melting due to breakdown of phengite and amphibole in retrogressed eclogite: an example from the Precambrian Algonquin terrane, western Grenville Province, Canada. Precambrian Research, 352, 105965. [LINK; PDF]

  • Cao, W., Gilotti, J. A., and Massonne, H.-J., 2020. Partial melting of zoisite eclogites from the Sanddal area, North-East Greenland Caledonides. European Journal of Mineralogy, 32(4), 405-425. [LINK; PDF]

  • Cao, W., Gilotti, J.A., Massonne, H.J., Ferrando, S. and Foster Jr, C.T., 2019. Partial melting due to breakdown of an epidote‐group mineral during exhumation of ultrahigh‐pressure eclogite: An example from the North‐East Greenland Caledonides. Journal of Metamorphic Geology, 37(1), p. 15-39. [LINK]

Example conference abstracts (*denotes student author):

  • Dwyer, T.*, Cao, W., and Fornelle, J. H., 2020. Pressure-temperature path of migmatite from Lac Dumoine Terrane, western Grenville Province. GSA Northeastern/Southeastern Section Meeting.

  • Guest, E.*, Cao, W., and Massonne, H.-J., 2019. Pressure-temperature path of eclogites from the Grenville Province, Southern Ontario. Geological Society of American Abstracts with Programs. Vol. 51, No. 1. Portland, ME. doi: 10.1130/abs/2019NE-328289.

Photomicrograph showing neoblastic garnet (Grt II) which displays straight boundaries (red arrows) against plagioclase, and sharp cuspate texture (yellow arrows) from plagiocalse under cross-polarized light (XPL).

2. Plate tectonics and subduction-exhumation processes

Subduction of oceanic crust is a critical component of plate tectonics that actively recycles crustal materials back into the mantle and contributes to arc processes. Such processes has been operating for billions of years, although arguments exist regarding the timing of the onset of plate tectonics. Exhumed metamorphic rocks from ancient subduction zone records 'fossilized' geological and petrological processes, which are ideal candidates to investigate subduction zone processes. Current projects aim to decipher 1) the onset of plate tectonics, 2) the subduction and exhumation processes, and 3) the fluid processes in the exhumed crustal and mantle rocks, by examining metamorphic rocks from two 'fossil' subduction zones, the Jinsha suture and Longmu Co-Shuanghu suture in Tibetan Plateau.

Example publications:

  • Hernandez-Uribe, D., Palin, R., Cone, K.A. and Cao, W., in press. Petrological implications of seafloor hydrothermal alteration on subducted mid-ocean ridge basalt. Journal of Petrology. [LINK]

  • Palin, R. M., Santosh, M., Cao, W., Li, S.-S., Hernandez-Uribe, D., and Parsons, A., 2020. Secular changes and the onset of plate tectonics on Earth. Earth-Science Review, 207, 103172. [LINK; PDF]

  • Cao, W., Yan, D.P., Qiu, L., Zhang, Y. and Qiu, J., 2015. Structural style and metamorphic conditions of the Jinshajiang metamorphic belt: Nature of the Paleo-Jinshajiang orogenic belt in the eastern Tibetan Plateau. Journal of Asian Earth Sciences, 113, pp. 748-765. [LINK]

Example conference abstracts:

  • Qiu, L., Yan, D.-P. Yan, Wells, M. L., Cao, W., Yu, W., Li, X.-T., Wang, T., and Kong, R., 2019. Timing of Crustal Melting and Orogeny: Paleo-Tethys Orogenic Evolution from Subduction to Collision in Eastern Tibetan Plateau. AGU Fall Meeting.

X-ray maps (Na, Ca, Mg & Fe) of retrograde coronitic textures around kyanite and garnet. The figures shows symplectite of sapphirine + plagioclase, spinel + plagioclase and corundum + plagioclase after kyanite surrounded by plagioclase.

3. Development of petrographic textures

Retrograde textures (e.g. corona, symplectite) are common in high-grade metamorphic rocks. Development of retrograde textures reflect physiochemical conditions in rocks or rock domains. My group currently aims to decipher the forming mechanism and conditions of these retrograde textures.

Details later...

4. Other projects

4.1 Metallogenesis

Details later...

Publication:

  • Dai, Y., Yu, X., Zhang, L., Cao, W., Zhu, Y. and Li, C., 2014. Geology, isotopes and geochronology of the Caijiaping Pb–Zn deposit in the North Wuyi area, South China: Implications for petrogenesis and metallogenesis. Ore Geology Reviews, 57, pp. 116-131.

  • Qiu, L., Yan, D.P., Ren, M., Cao, W., Tang, S.L., Guo, Q.Y., Fan, L.T., Qiu, J., Zhang, Y. and Wang, Y.W., 2018. The source of uranium within hydrothermal uranium deposits of the Motianling mining district, Guangxi, South China. Ore Geology Reviews, 96, pp. 201-217.