Biblioteca Digital

Eocene sediments drilled at the East Tasman Plateau (ETP) exhibit well-defined cycles, high-resolution magnetic stratigraphy, and environmentally-controlled dinoflagellate and diatom distribution patterns. We derive a cyclostratigraphy from the spectral analysis of high-resolution elemental concentration records (Ca, Fe) for this shallow marine time series spanning the middle to early late Eocene (C16n.2n - C21). Changes in carbonate content, the ratio between Gonyaulacoid and Peridinioid dinocysts, and relative abundance of "oligotrophic" diatoms serve as proxies for a high-resolution climatic and sea-level history with high values representing high sea-level stands and decreased eutrophy of surface waters. Changing ratios between high latitude dinocysts versus cosmopolitan species provide clues on sea surface temperature trends and water mass exchange. Our results show that the relatively shallow-water middle Eocene environments of the ETP are influenced by orbitally-forced climatic cycles superimposed on third order relative sea-level changes. Changes in the dominance of Milankovitch frequency at ~38.6 Ma (late Eocene) is related to an initial deepening-step within the Tasmanian Gateway prior to the major deepening during the middle late Eocene (~35.5 Ma). Decreasing sedimentation rates at 38 Ma and 37.2 Ma reflect winnowing associated with sea-level fall. This episode is followed by renewed transgression. Dinocyst distribution patterns indicate high latitude, probably cool temperate surface water conditions throughout, with the exception of a sudden surge in cosmopolitan species near the base of subchron C18.2r, at ~41 Ma; this event is tentatively correlated to the Middle Eocene Climatic Optimum.

Veja mais

1999 University of Michigan Football Team

Relevância:

30.00% 30.00%

Publicador:

Resumo:

Back Row: Paul Schmidt, Mike Gittleson, Mike Elston, Teryl Austin, Brady Hoke, Jim Herrmann, Mike DeBord, Fred Jackson, Bobby Morrison, Stan Parrish, Erik Campbell, Terry Malone, Scot Loeffler, Jon Falk, Scott Draper, Phil Bromley, Jim Schneider

8th Row: Tim Murphy, Dr. Edward Wojtys, Dr. C. Daniel Hendrickson, Kevin Undeen, Mark Borgman, Brian Smalls, Michael Kaselitz, Joe Ghannam, Tommy Huff, Dave Eklund, Rick Brandt, Bob Bland, Mark Ouimet, Kelly Cox, Dennis Coyle, Zach Adami

7th Row: Jason Clyne, Brandon Williams, Greg Brooks, Shantee Orr, Jeremy LeSueur, Carl Biggs, Dave Pearson, Ronald Bellamy, Tyrece Butler, John Navarre, Andy Mignery, Andy Brown, Grant Bowman, Courtney Morgan, Phil Brabbs*, Kyle Blerlein, Chris Roth

6th Row: P.J. Cwayna, TommyJones, Tad Van Pelt, Dwight Mosley, Scott Panique, Stephen Baker, Blake Nasif, Joe Sgroi, Tony Pape, Demeterius Soloman, Norman Boebert, John Spytek, Phil Brackins, B.J. Askew, Charles Drake, Brent Cummings, Ryan Beard, Jon Shaw

5th Row: Aaron Richards, Jason Ptak, Todd Howard, Walter Cross, Julius Curry, Justin Fargas, Bennie Joppru, Dan Rumishek, Dave Petruziello, Shawn Lazarus, Victor Hobson, Dave Armstrong, Deitan Dubuc, Cato June, John Wood, Kyle Froelich, Kirk Moundros

4th Row: Mark Bergin, Cyle Young, Bob Fraumann, Kurt Anderson, Todd Mossa, Rudy Smith, Evan Coleman, Hayden Epstein, Larry Foote, Joe Denay, Drew Henson, Dave Terrell, Marquise Walker, Gary Rose, Michael Manning, Jeremy Miller

3rd Row: Matt Johnson, Ryan Parini, James Whitley, Bill Seymour, Anthony Thomas, Shawn Thompson, Adam Adkins, Jake Frysinger, Ben Mast, Eric Brackins, Eric Rosel, DeWayne Patmon, Dan Williams, Cory Sargent, Brandon Kornblue

2nd Row: Tate Schanski, Jeff Smokevitch, Kevin Bryant, Eric Wilson, Grady Brooks, David Brandt, Steve Frazier, Steve Hutchinson, Jeff Backus, Jason Kapsner, Andy Sechler, Eric Warner, Ken Jackson, Jeff Del Verne

Front Row: Chris Ziemann, Josh Williams, Tom Brady, Patrick Kratus, DiAllo Johnson, Rob Renes, Head Coach Lloyd Carr, Dhani Jones, Ian Gold, Marcus Knight, Tommy Hendricks, Aaron Shea, James Hall

Veja mais