ch5_ fluvial depositional system
TRANSCRIPT
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 1/41
FLUVIAL DEPOSITIONAL SYSTEM
Fluvial sedimentation is primarily ontrolled !y t"e #luvial proesses$
mostly related to rivers% T"ree ma&or types o# #luvial sedimentation are
identi#ied'
Alluvial Fan Sedimentation
Alluvial Plain Sedimentation
Me(a#an Sedimentation
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 2/41
An alluvial fan is a fan shaped body of coarse grained sediments, formed bymountain stream at the base of a mountain front where a steeper slope
changes abruptly into a gentle slope.
Alluvial #an s"o)s t)o types o# deposits
1. Debris flow deposits
2. Water laid deposits (Stream channel, Sheet flood, Sieve
Alluvial Fan Sedimentation
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 3/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 4/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 5/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 6/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 7/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 8/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 9/41
Alluvial Plain Sedimentation Alluvial plains are vast areas formed by river channel activity, flood processes.
*iver +"annel Deposits
'ivers occur in straight, braided, meandering and anastomosing patterns.
n a river channel deposition ta)es place essentially as fluvial bars, which
are braid bars, point bars and lateral bars.
*ase of a river channel deposit shows a channel lag deposit followed by
fluvial bar deposits.
+luvial bar deposits are made up of mostly fining upward seuences,
showing from bottom towards top, large-scale cross-bedding, hori"ontal
bedding, small ripple bedding, silty hori"ontal bedding and mud.
Architectural element analysis is helpful in identification of nature of sand
bars. &icroforms (ripples, mesoforms (megaripples and macroforms (unit
bar are identified.
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 10/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 11/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 12/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 13/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 14/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 15/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 16/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 17/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 18/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 19/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 20/41
T"e ei("t !asi ar"itetural elements in #luvial
deposits% ,Miall -.//a$ !0 modi#ied #rom Maill -./1
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 21/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 22/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 23/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 24/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 25/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 26/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 27/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 28/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 29/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 30/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 31/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 32/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 33/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 34/41
Me(a#an Sedimentation
Me(a#ans are lar(e4si5ed #ans #ormed in "umid limate !y lar(e rivers )it" "u(e
)ater and sediment supply% T"e #ans s"o) anastomosin( and diver(in( river
"annels )"i" &oin to(et"er at t"e distal end o# t"e me(a#an%
T"e me(a#an deposits s"o) a distint 5onation into #our 5ones #rom pro6imal todistal part%
Zone I
Area o# (ravelly$ s"allo) !raided "annels%
Zone II
Sandy !raid plain )it" many s"allo) "annels%Zone III
Area o# anastomosin( "annels%
Zone IV
Area o# meanderin( "annels )it" !road inter#luves%
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 35/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 36/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 37/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 38/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 39/41
Terminal #ans
In semi4arid limate )it" lo) (radient and lar(e sediment supply #ine4
(rained #ans are developed% In terminal #ans$ a6ial stream !ran"es
into small distri!utaries )"i" lose t"eir identity in lo)er #an% T"erivers an !e desri!ed as distributive river system% In t"e lo)er #an
area small )ater !odies and #e) ep"emeral streams are present%
Pro6imal part s"o)s mainly sandy deposit$ middle part s"o)s muddy
sediments )it" sandy lenses$ t"e lo)er part is made up o# muddy
sediments )it" rare t"in sandy "ori5ons%
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 40/41
8/9/2019 Ch5_ Fluvial Depositional System
http://slidepdf.com/reader/full/ch5-fluvial-depositional-system 41/41