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2007 Michigan Academy Meeting -The glacial section at Grand
 

2007 Michigan Academy Meeting -The glacial section at Grand

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An oral presentation given at the Michigan Academy of Science Meeting in 2007.

An oral presentation given at the Michigan Academy of Science Meeting in 2007.

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    2007 Michigan Academy Meeting -The glacial section at Grand 2007 Michigan Academy Meeting -The glacial section at Grand Presentation Transcript

    • Welcome to the Geological Sciences section of the Michigan Academy of Sciences, Arts, and Letters 2007 Meeting at Ferris State University
    • The glacial section at Grand Valley State University: A Lake Michigan lobe advance into a glacial lake Patrick M. Colgan Grand Valley State University Allendale, Michigan
    • Ottawa County Michigan 10 kilometers N Counties Lake Plain GVSU Grand Rapids Lake Border Lake Border Advance of the moraines Lake Michigan Lobe ~14,500-15,500 14C yrs B.P.
    • Allendale Allendale Delta GVSU Campus end moraine Glacial Lake Chicago Plain 1 km
    • 1 Lake Ontario Hall N 2 500 meters
    • Section 1: Silt-rich diamicton with oxidized vertical joints, striated clasts, high density.
    • Dm Dms Sr-Sx Section 1: Contact between diamicton and sand. Shear zone between.
    • clast of diamicton ripples In silty sand Section 1: Clast of reddish diamicton in silty sand.
    • Sx-Sr Fl Sx-Sr Fl Sp Section 1: planar bedded fine sands, crossbedding, ripples, and fines.
    • Sx-Sr Fl Sp Section 1: laminated fines
    • Section 1 – Ravine Apartments GV-1-2 (diamicton - basal till) texture meters C Z S GD sediment sediment 100 90 samples clay silt sand gr facies 80 70 D1 % coarser Dm erosional 60 surface D2 50 40 0 30 clast of Dm 1 20 10 Sr 0 0.0010 0.0100 0.1000 1.0000 10.0000 2 S1 diameter (mm) Sx 3 GV-2-1 (sandy silt - glaciolacustrine) 4 100 Fm-Fl 90 5 clay silt sand gr 1 Sr S2 80 70 % coarser 60 Sx 50 40 30 Fm-Fl 6 20 S3 7a 10 Sp-Sr 7b 0 0.0010 0.0100 0.1000 1.0000 10.0000 8 Fm-Fl diameter (mm) Sr S4 9 2 Fm-Fl 10 GV-2-13 (clayey silt - glaciolacustrine ) Sp S5 100 Fm-Fl 11 gr 90 clay silt sand Sr S6 80 12 70 % coarser 60 50 40 covered 30 20 10 3 Fl-Fm 13 0.0010 0.0100 0.1000 1.0000 0 10.0000 diameter (mm)
    • 1 Lake Ontario Hall N 2 500 meters
    • Section 2: Silt-rich diamicton with striated and wedge shaped clasts.
    • rippled and cross-bedded fine sands fines rippled and cross-bedded fine sands fines rippled and cross-bedded fine sands planar bedded fine sands trough cross-bedded sands Section 2
    • Section 2 – planer bedded sand with scour of rippled sand
    • Section 2 – trough cross bedded sands
    • 2 cm Section 2 - Granite clasts and clay rip-up clasts in laminated and deformed clay
    • Section 2 - Thick clay bed in fine sand.
    • meters C Z S G D Section 3 – South Ravine 0 Fm-Dm Samples covered St-Sr (A) 1 7 SR2-10 (fine sand) Fl-Fm 9 Sr (A) St-Sr (A) 6 Fl-Fm 8 100 St-Sr (A) 90 5 2 4 clay silt sand gr 80 Sl 70 % coarser 3 60 Sl 2 50 3 St-Sr (A) 1 40 Dml-Fl 18 30 St-Sr (A) 20 Fl-Fm 10 4 Sr St-Sr (A) 0 Sr 15 0.0010 0.0100 0.1000 1.0000 10.0000 Fl-Fm 14 12 diameter (mm) 5 St-Sr Fl-Fm 11 SR2-16 (silty clay) Sr 6 10 St 100.0 90.0 Sl 80.0 7 70.0 % coarser 60.0 clay silt sand gr 50.0 St-Sr (A) 40.0 8 30.0 20.0 St inclusions of clasts 10.0 of fines in sand 0.0 9 Dmm Fm-Fl 16 0.0010 0.0100 0.1000 1.0000 10.0000 17 diameter (mm) Sr (A) 10 St
    • 141 (523) 208 (520) 147 (518) 1 190 (510) 193 (479) 194 (479) Lake Ontario Hall 2 N 1 km
    • North to South Cross Section across GVSU Campus Lake diamicton Ravine Ontario (basal till) Apartments Hall Section 2 South Ravine elevation (ft) fine silty sand (lacustrine) clay, silt and fine sand (lacustrine) diamicton (basal till)? Marshall Sandstone ~ 480-510 feet S distance (meters) N vertical exaggeration ~16:1
    • Interpretations • Upper diamicton is basal till deposited during Lake Border advance. • Lower sequence is interpreted as numerous underflows (turbidites) of fine silty sand overlain by thin rainout deposits of clay and silt. • Till was deposited directly on lake sediments and inclusions of till suggest that the advance occurred as sediment was deposited into a proglacial lake. • Minor debris flows and rainout layers are present.
    • Morainal bank sedimentation model rain out of fine silt and clay underflows of sand (Sx-Sp-Sr) deposition debris of basal till (Dm) clay and silt flows (Dml) (Fm-Fl) Adapted from Benn and Evans (1998) after Powell and Domack (1995)
    • Future Work • Collect vibracores in areas of poor exposure to see how extensive the lacustrine sediments are. • Compare diamicton clasts in upper sand to basal till with grain size and clay mineralogy. • Collect vibracores to see what is below the measured sections.
    • Acknowledgements • Thanks to the GVSU geomorphology students who have worked on the ravine sediments in projects with me and other faculty at GVSU.