Current Research Areas

Research in New England

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Roden-Tice, Mary K. and Wintsch, Robert P. Early Cretaceous Normal Faulting in Southern New England: Evidence from Apatite and Zircon Fission Track Ages (2002). Journal of Geology, v. 110, p. 159-178.

New apatite and zircon fission-track (AFT, ZFT) ages from Mesozoic sediments and adjacent crystalline rocks from southern New England reveal age gradients from middle Jurassic to early Cretaceous. These gradients reflect the rotation of crustal blocks after the setting of the youngest AFT ages (~140 Ma). AFT ages of 168-98 Ma for 32 samples of Paleozoic metamorphics east and west of the basin and sediments within the Hartford basin of MA and CT indicate that unroofing in these regions occurred from Late Jurassic to Early Cretaceous. In both the Hartford basin and rocks from crystalline terranes east of the basin, AFT ages show a regional trend of increasing age to the east, suggesting a down to the east rotation of ~10° in each area. ZFT ages from both the Hartford basin (167-238 Ma) and Bronson Hill terrane (147-196 Ma) support this gradient of eastward increase in AFT age. A south to north gradient of decreasing AFT age (139-107 Ma) for the sediments in the Hartford and Deerfield basins of MA and CT suggests a 1° hinged uplift to the north that postdates the youngest AFT age of ~100 Ma. Final juxtaposition of AFT ages across the Border fault along the eastern margin of the Hartford basin in MA and CT indicates displacement younger than the youngest AFT ages of < 100 Ma, Late Cretaceous. Thus the age of the graben structure of the Hartford basin is Cretaceous, and this structure cannot be cited as evidence that these basins are early Mesozoic "rift" basins. The project was funded by RUI NSF grant (EAR-9909210).

Research in the Olympic Mountains, Washington State

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Brandon, M.T., Roden-Tice, M.K., and Garver, J.I., 1998. Late Cenozoic Exhumation of the Cascadia Accretionary Wedge in the Olympic Mountains, northwest Washington State. Geol. Soc. America Bull., v. 110, p. 985-1009.

The apatite fission-track method is used to determine the exhumation history of the Olympic subduction complex, an uplifted part of the modern Cascadia accretionary wedge. Fission-track ages are reported for 35 sandstones from the OSC, and 7 sandstones and 1 diabase from the Coast Range terrane, which structurally overlies the OSC.


What is fission-track analysis?
Fission-Tracks in Apatite
200 X	1600 X
Research on the Norumbega Fault System, Maine West, David P., Jr. and Roden-Tice, Mary K., 2003. Late Cretaceous reactivation of the Norumbega fault zone, Maine: Evidence from apatite fission-track ages. Geology, v. 31, p. 649-652. Apatite fission-track ages from opposite sides of the Norumbega fault zone in southern Maine reveal a significant Early Cretaceous time-temperature discontinuity across the structure. Ages west of the fault zone range from 113 to 89 Ma, while those to the east are significantly older, ranging from 159 to 140 Ma. This discontinuity is best explained by an episode of significant east-side-down vertical movement along the Norumbega fault zone in Late Cretaceous time. When combined with earlier structural and thermochronological studies, these results suggest that faults mapped within the Norumbega fault zone were intermittently active from Middle Devonian to Late Cretaceous time, and that the structure is a fundamental zone of crustal weakness. This research is currently funded by a collaborative RUI NSF grant (EAR-0308938).
Research in the Adirondack Mountains, New York Click on the Adirondack Region to see more ----------> Roden-Tice, M. K., Tice, S. J., Schofield, I. S., 2000. Evidence for Differential Unroofing in the Adirondack Mountains, New York State Determined by Apatite Fission-Track Thermochronology. Journal of Geology, v. 108, p.155-169. Apatite fission-track (AFT) thermochronologic data for 43 samples from the Adirondack Mountains in upstate New York provide evidence that Late Jurassic to Late Cretaceous unroofing (exhumation) has occurred in this region. AFT age discontinuities exist and are associated with regional-scale normal faults suggesting that post-Early Cretaceous displacement occurred along these structures. The goal of this project is to map the extent of post-Early Cretaceous unroofing between the Adirondack Mountains in northern New York state and the Hartford basin in central Massachusetts and Connecticut. This research was funded by RUI NSF grant (EAR-9909210).