Basin typesTurbidite deposits

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Basin types-Turbidite deposits Type A-
Oceanic crust with long lived sediment supplies
No tectonics Mid-Plate margins-life
times of up to 20millionYrs.
Atlantic and Indian Ocean margins
Type B- Oceanic crust with long lived
sediment supply but Lower than A but
sufficient to override tectonics With
tectonics Along transform fault margins,
long lived systems of up to 20 million yrs. Parts
of California margin, Indian Ocean, Sea of Bengal
Basin
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Type C- Continental crust with large
sediment supply Structurally controlled,
partially tectonic Sea level plays a large
role in sediment supply and basin shape
Best example is Pyrennes system in Northern
Spain-part of old Tethyan Sea Way in
early Cenozoic and Appenines in Italy
Type D- Continental crust with
large sediment supply Very active
tectonics Very short life times in the
order of 104 to 105yrs. Places like the
California Border land-Navy Fan regions
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Type C-some tectonics But mostly sea-level
Controlled-Pyrennes
Type D-high tectonics Short life and lots of Sed.
Navy Fan, Calif
Type B-limited tectonics High sed.
Supply- Monterey Fan and Ganges River Delta
Type A-no tectonics And lots of seds-Miss. Delta
complex
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To view submarine fans you must use Seismics and
coring which is difficult However in areas of
rapid sea-level change Associated with uplift
such as the Pyrennees, Alps and Appenines in
southern Europe You can look at these exposed on
land And get a much better idea of the
dimensions Of these systems
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These are what Are called flysch Deposits
because When they Originally started Looking at
these They were unsorted Jumbled messes- This
picture is From the Swiss Alps
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Micropaleo people Looked at these and They had an
Assortment of deep And shallow water Forms-this
confirms That these deposits Start in shallow
water And travel to deep water
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Until you see the Scale of these it Is hard to
imagine The immensity- Here you see Hundreds of
Turbidite sequences Probably Representing
several Million years
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On a finer scale It is possible to look At the
hemipelagic Sediments in between Turbidites and
Determine something About water depth they were
Deposited in- this Sequence is in the Italian
Appenines and Is early Cenozoic as The Tethys
opened up
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Another view of the expanse of these flyschs In
the Italian Appenines
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As you get to the deeper part of the basin You
start to see mostly distal turbidites- Thick
muds-this is also in Italy
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The situation is different in Eastern SpainWhere
there was obviously tectonics but There is a
major sea-level component as We see many shallow
water deposits Intercalated with the deeper
water turbidites
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Emiliano Mutti who Is a pioneer Italian scientist
who Was one of the first To realize that
to Understand these Systems you had to Look at
exposed Systems(in white hat)
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Sand layers typical Of the middle part Of a Bouma
sequence
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On a finer scale You can see the cross Bedding
associated With current speeds Changing
directions And velocities as They travel down
a slope
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Some of the sharp Changes associated With
tectonic/sea-level Movements that Cause areas to
go From turbidite Basins to shallow Water systems
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Sharp lithology changes associated with
channel cutting
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Interlocking channels cause the sharp lithologic
changes
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A deep channel exposed in Spain-several Hundred
meters across
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Progressively Less mud produces A more sand
rich Sequence from type III to I
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One of the aspects Most often missing In sequence
Stratigraphy is Sea-level control However in
Spain There are shallow Water(here salt Marsh)
deposits That allow very strong Controls on
where Sea level was which In turn good control On
basin configuration
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This thick sequence of sediments is largely
deepsea turbidites With interspersed shallow
water and shelf sediments in Spain
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As in the previous slide it is easy to see
all The facies changes when its exposed
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One of the many Benefits of working In this area
is the Beautiful 1000yr Old churches-this Is is
still in use