c10_SC_marine_part1

c10_SC_marine_part1 - Tide-dominated estuaries High tidal...

Info iconThis preview shows pages 1–11. Sign up to view the full content.

View Full Document Right Arrow Icon
Tide-dominated estuaries • High tidal energy influences upper reach of estuary • Well-mixed water • Elongate sand bars parallel length of estuary • Herringbone cross-bedding (landward and seaward dip directions) • Flaser -bedding mud drapes forms during slack water • Mud accumulates in low-energy areas and in salt marshes • Estuarine sediments typically contain brackish-water fauna – E.g., Oysters, mussels, gastropods
Background image of page 1

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Idealized tide-dominated estuary
Background image of page 2
9.5 lagoon systems Lagoon = shallow stretch of seawater near partly or completed separated from nearby sea by a low, narrow elongated strip of land • commonly coast parallel (unlike estuaries) • Many have no significant freshwater runoff • Limited circulation with open ocean • Most modern lagoons formed behind spits or barriers
Background image of page 3

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Lagoon system enclosed by a barrier- island chain C. Hatteras SC
Background image of page 4
Some characteristics of lagoon deposits • Hypersaline to fresh conditions depending on climate • Mainly fine-grained sediment bc low energy • Sandy sediments associated with tidal transport/deposition at inlet mouths • Storms may deliver wind-blown sand • Sands are usually horizontally laminated but may display ripple cross laminations • Faunas are highly variable but of low diversity • Evaporites in arid-area lagoons • Algal mats and mudcracks within supratidal zones
Background image of page 5

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
St. Mary River Formation
Background image of page 6
9.6 tidal-flat systems • Form on mesotidal / macrotidal coasts • Along low-relief open coasts or behind barriers – Within estuaries, bays, backshores of barrier-island, deltas and open coasts • Marshy and muddy to sandy areas partially uncovered by rise/fall of tides • Flat covered during high tide • Flat width from few kms to 25 kms
Background image of page 7

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
Tidal Flat Depositional setting • Subtidal zone = below mean low tide, – Subjected to highest tidal current velocities • Bedload transport and deposition predominates in tidal channels • Intertidal zone = between low and high tide – exposed once or twice daily – Usually vegetation free – Bedload and suspension sedimentation occurs • Supratidal zone = above high tide – exposed most of time – incised by tidal channels – Some supratidal zones are salt marshes or sabkhas
Background image of page 8
Tidal flat tidal zones
Background image of page 9

Info iconThis preview has intentionally blurred sections. Sign up to view the full version.

View Full DocumentRight Arrow Icon
characteristics of tidal flats • Sand deposition dominates subtidal zone – Herringbone cross-stratification and/or reactivation surfaces in association with reversing flow directions • Intertidal - zone tidal currents dominate sedimentation in tidal channels
Background image of page 10
Image of page 11
This is the end of the preview. Sign up to access the rest of the document.

This note was uploaded on 02/20/2010 for the course GEOL 3032 taught by Professor Bouma,a during the Fall '08 term at LSU.

Page1 / 40

c10_SC_marine_part1 - Tide-dominated estuaries High tidal...

This preview shows document pages 1 - 11. Sign up to view the full document.

View Full Document Right Arrow Icon
Ask a homework question - tutors are online