About

Michael D. Brown is the Chair and Professor of Kinesiology at the University of Maryland. He received his PhD in exercise physiology from the University of Maryland and completed a postdoctoral fellowship in the Department of Internal Medicine and the Institute of Gerontology at the University of Michigan, where he studied age-associated hypertension. His research focuses on hypertension, vascular health, and exercise in African Americans, utilizing complementary human and cell models to address his research questions. Dr. Brown has held academic positions at Auburn University, Temple University, and the University of Illinois, Chicago, before joining the University of Maryland in 2022. His professional affiliations include fellowships in the American Heart Association Council for High Blood Pressure Research, the American College of Sports Medicine, and the National Academy of Kinesiology. He serves on various national committees and has recently completed a term on the Board of Trustees for the American College of Sports Medicine, where he also chairs the Diversity Action Committee. His research program has been consistently funded by the NIH and AHA, and he has authored over 80 peer-reviewed publications.

Research topics

• Paleontology
• Geology
• Geochemistry
• Earth science
• Petrology
• Geophysics

Selected publications

• The evolution of Earth’s early continental crust

  Nature Reviews Earth & Environment · 2025-08-14 · 2 citations

  article
  PublisherDOI

• Deformation Microstructures and Seismic Properties of UHP Eclogites: Response to Strain Localization, <i>P</i>–<i>T</i> Path and Fluid/Melt Interaction Within a Paleo‐Subduction Channel

  Journal of Geophysical Research Solid Earth · 2025-03-29 · 5 citations

  article

  Abstract Providing spatio‐temporal constraints on what influences the rheology of deeply subducted continental crust during subduction–exhumation remains elusive but crucial for understanding the exhumation dynamics of ultrahigh pressure (UHP) terranes. Here, we report results of a systematic study of microstructures, crystallographic preferred orientations (CPOs) and seismic properties of four UHP–HP eclogites formed along a common P – T path from Yangkou Bay, Sulu belt, China. The eclogites have different bulk compositions and record heterogeneous strain patterns. Peak metamorphic conditions (800°C–900°C and &gt;5.5 GPa) were retrieved from early F1 isoclinal fold hinges. Subsequent overprinting by F2 tight folds occurred during the transition to quartz‐eclogite facies. Localized shear zones exhibit amphibolite‐facies retrogression, indicative of enhanced fluid activity. Omphacite exhibits crystal plasticity, while garnet displays a brittle–plastic transition during exhumation. A change from S‐ to L‐type CPO in omphacite was controlled by folding geometry during subduction–exhumation. Strain localization controlled intergranular fluid connectivity and redistribution, correlating with increasing strain from F1 folds to localized shear zones. This process led to progressive dynamic recrystallization, and changes in deformation mechanisms and seismic properties. Dynamic recrystallization resulted in significant grain refinement, thereby triggering diffusion creep assisted grain boundary sliding in the presence of fluid. Seismic anisotropy is linked to the omphacite fabric and the presence of phengite, with modal phengite as the primary determinant in UHP–HP eclogites. Fluid migration controlled by strain localization led to heterogeneous weakening of eclogite, which enabled exhumation of tectonic slices of UHP crustal rocks from mantle depths.

  PublisherDOI

• Archean tectonics: are we converging on a consensus?

  2025-01-01

  article1st authorCorresponding
  PublisherDOI

• Ultraslow cooling of an ultrahot orogen

  Geology · 2024-09-09 · 14 citations

  articleOpen access

  Abstract To constrain the rate of cooling of lower-crustal rocks from an ultrahot orogen, we determined both the age and equilibration temperature of metamorphic zircon from six widely spaced samples of metasedimentary garnet–sillimanite gneiss from the Eastern Ghats Province in eastern India. For the combined data set of metamorphic zircon, concordant dates decrease continuously within 2σ uncertainty from around 950 Ma to 800 Ma, consistent with ∼150 m.y. of zircon crystallization. Ti-in-zircon temperatures for each dated spot during this period decrease with age, corresponding to linear cooling rates ranging from 0.26 to 0.90 °C/m.y. We propose that retention of heat-producing elements in the lower crust of the Eastern Ghats Province and a low net erosion rate were responsible for ∼150 m.y. of ultraslow cooling.

  PublisherOA PDFDOI

• Ultrahigh temperature (UHT) metamorphism

  Treatise on Geochemistry · 2024-09-17 · 1 citations

  book-chapter
  PublisherDOI

• Is plate tectonics a post-Archean phenomenon? A petrological perspective

  Journal of the Geological Society · 2024-07-17 · 28 citations

  articleOpen access1st authorCorresponding

  The petrogenesis of contemporary igneous and metamorphic rocks is commonly explained by plate tectonics, but how far back in time does this relationship hold? Here we investigate whether the distinctive petrological features of recent ocean crust, subduction-related magmatism and regional metamorphism can be unambiguously identified in the Archean geological record. From an igneous perspective based on geological relationships and Th–Nb systematics, it is difficult to claim that any Archean ‘ophiolite’ was part of a global plate system rather than deriving from a plume ascending through attenuating lithosphere. Furthermore, the rarity of subduction-related rocks, particularly their plutonic equivalents, which have good preservation potential, is consistent with the concept of local convergence and short-lived subduction. From a metamorphic perspective, the appearance of orogenic eclogites in the Paleoproterozoic, the widespread occurrence of blueschists and ultrahigh-pressure metamorphic rocks since the late Neoproterozoic, and a change from a unimodal to a bimodal distribution of metamorphic T / P during the Proterozoic, are responses to secular cooling and the evolution of global tectonics since the Archean. Our petrological perspective is that plate tectonics analogous to that on Earth today is probably a post-Archean phenomenon.

  PublisherDOI

• Paleoarchean metamorphism in the Acasta Gneiss Complex: Constraints from phase equilibrium modelling and in situ garnet Lu–Hf geochronology

  Journal of Metamorphic Geology · 2024-01-25 · 15 citations

  articleOpen access

  Abstract The oldest known evolved (felsic) rocks on Earth ( c . 4.03 Ga) are found in the Acasta Gneiss Complex (AGC) in north‐western Canada and represent a fundamental keystone in unravelling the geological processes governing crustal growth and differentiation during the Hadean and early Archean. Although the timing of multiple episodes of magmatism, metamorphism and deformation in these tonalitic gneisses has been investigated extensively, the metamorphic pressure–temperature ( P–T ) conditions recorded by the rocks are poorly constrained. Here, we use phase equilibrium modelling coupled with in situ garnet Lu–Hf geochronology and trace element analysis for two garnet‐bearing tonalitic gneisses to decipher the metamorphic history of the AGC. The observed mineral assemblages are consistent with peak metamorphic conditions of T = 725–780°C and P = 4.5–6.2 kbar and the generation of a small amount of melt (&lt;7 vol.%). Garnet geochronology constrains the age of metamorphism to 3.3–3.2 Ga, consistent with previous evidence for a late Paleoarchean tectono‐metamorphic event in the AGC. Subsequent isotopic disturbance of garnet at c . 1.9 Ga is interpreted to correspond to a modification of the primary Lu–Hf systematics in response to garnet resorption/recrystallization during the Paleoproterozoic Wopmay orogeny, resulting in significant scatter between these two age components. Our study adds to the small number of published P–T data for metamorphic rocks older than 2.8 Ga and shows that tonalitic gneisses in the AGC record a high apparent thermal gradient of ~140°C/kbar in the late Paleoarchean. This thermal gradient is the highest among the limited dataset, but is broadly similar to data from other Paleoarchean‐Mesoarchean crustal rocks in recording high T/P ratios (&gt;77.5°C/kbar).

  PublisherOA PDFDOI

• Surface evolution during the mid-Proterozoic stalled by mantle warming under Columbia–Rodinia

  Earth and Planetary Science Letters · 2023-02-27 · 29 citations

  article
  PublisherDOI

• Making andesite through shallow hybridization of magmas derived from variably enriched lithospheric mantle

  Zenodo (CERN European Organization for Nuclear Research) · 2023-05-22 · 1 citations

  datasetOpen accessSenior author

  We integrate textural and in situ compositional information from plagioclase and clinopyroxene (Cpx) phenocrysts together with groundmass compositions in early Cretaceous andesite dykes within the Sulu belt of China to propose a new petrogenetic model for andesite. Plagioclase phenocrysts are mostly andesine; they are depleted in high field strength elements (HFSE). However, clinopyroxene (Cpx) phenocrysts are either reversely-zoned (type I) or homogeneous (type II), with the zoned Cpx divided into subtypes IA and IB. All Cpx has high Mg#, low Na₂O and generally low Al₂O₃, with depletions in HFSE and variably high ⁸⁷Sr/⁸⁶Sr ratios, suggesting crystallization above the Moho from magmas derived from enriched lithospheric mantle. The cores of type IA/IB and type II Cpx have normal major- and trace-element compositional variations and similar ⁸⁷Sr/⁸⁶Sr ratios to each other and to plagioclase, consistent with fractional crystallization from a common magma (magma 1). The rims of type IA and IB Cpx also have normal major- and trace-element compositional variations, but these are not as evolved as the cores, and the rims have lower ⁸⁷Sr/⁸⁶Sr ratios, demonstrating crystallization from an isotopically-distinct magma (magma 2). Based on modelled major and rare earth element compositions of magmas inferred to have been in equilibrium with different Cpx (± plagioclase) domains, the measured groundmass compositions can be reproduced by variable mixing between the two magmas. Our study demonstrates for the first time that andesite magma can be made through fractionation and shallow hybridization of magmas derived from variably enriched lithospheric mantle.

  PublisherDOI

• Making andesite through shallow hybridization of magmas derived from variably enriched lithospheric mantle

  Zenodo (CERN European Organization for Nuclear Research) · 2023-05-22

  datasetOpen accessSenior author

  We integrate textural and in situ compositional information from plagioclase and clinopyroxene (Cpx) phenocrysts together with groundmass compositions in early Cretaceous andesite dykes within the Sulu belt of China to propose a new petrogenetic model for andesite. Plagioclase phenocrysts are mostly andesine; they are depleted in high field strength elements (HFSE). However, clinopyroxene (Cpx) phenocrysts are either reversely-zoned (type I) or homogeneous (type II), with the zoned Cpx divided into subtypes IA and IB. All Cpx has high Mg#, low Na₂O and generally low Al₂O₃, with depletions in HFSE and variably high ⁸⁷Sr/⁸⁶Sr ratios, suggesting crystallization above the Moho from magmas derived from enriched lithospheric mantle. The cores of type IA/IB and type II Cpx have normal major- and trace-element compositional variations and similar ⁸⁷Sr/⁸⁶Sr ratios to each other and to plagioclase, consistent with fractional crystallization from a common magma (magma 1). The rims of type IA and IB Cpx also have normal major- and trace-element compositional variations, but these are not as evolved as the cores, and the rims have lower ⁸⁷Sr/⁸⁶Sr ratios, demonstrating crystallization from an isotopically-distinct magma (magma 2). Based on modelled major and rare earth element compositions of magmas inferred to have been in equilibrium with different Cpx (± plagioclase) domains, the measured groundmass compositions can be reproduced by variable mixing between the two magmas. Our study demonstrates for the first time that andesite magma can be made through fractionation and shallow hybridization of magmas derived from variably enriched lithospheric mantle.

  PublisherDOI

Recent grants

• Collaborative Research: Polyphase Orogenesis and Crustal Differentiation in West Antarctica

  NSF · $360k · 2010–2014

• Cooperative Research: Petrogenesis of HP and UHT Granulites from the Brasilia Fold Belt in Minas Gerais and Goias, Brazil

  NSF · $360k · 2003–2007

Frequent coauthors

• Tim Johnson

  70 shared

• Fawna J. Korhonen

  Geological Survey of Western Australia

  52 shared

• C. S. Siddoway

  40 shared

• Chris Yakymchuk

  38 shared

• Paul B. Tomascak

  37 shared

• Philip M. Piccoli

  University of Maryland, College Park

  36 shared

• Gary Solar

  36 shared

• C. Mark Fanning

  Australian National University

  29 shared

Labs

• University of Maryland Department of KinesiologyPI

Awards & honors

• Fellow of the American Heart Association Council for High Bl…
• Fellow of the American College of Sports Medicine
• Fellow of the National Academy of Kinesiology