KorEArtH NET

1. Alluvial Fan → Humid

    (선상지환경)     Arid

                              Glacial

    - 평면도

    - 수직단면도

    - Tectonic Setting - fault bounded

    - Process - debris flow, mud flow, sieve deposit, sheet flow

    - Sediments - no organic, oxidiging, lateral and vertical, facies change

    - Sequence characteristics

    - Pooly sorted, immature

    - Lenticular patterns - radiating

    - associated w/ eolian, fluvial, lacustrine marine

  기후에 따라 ┌ Humid - flanks of Himalaya (Modern)

                                   Alaska, Iceland (Ancient)

                   └ Arid - more steep, forming pediment

                              oxidation high permeability

                              small overlapping lobes and channels

                              felspathic and mafic minerals

                              Death valley, California

주요 facies 특성 요약:

  ① fossils and carbonates rare, evaporites

  ② poorly sorted, a great range in grain sizes, poor-stratified

  ③ poorly rounded, immature composition

  ④ major changes in lateral, vertical facies particularly in the downfan direction

  ⑤ rapid downfan decrease in clast size

  ⑥ oxidizing feature on sediments - red, brown, yellow, orange

  ⑦ No organic matter, not many fossils-vertebrate bones & plant fragments

  ⑧ most commonly medium to large-scale

      cross-strata and planar stratification, graded and inverse- graded bedding

  ⑨ lenticular, wedge-shaped geometry

  ⑩ sediment body-channelized(channel deposits) little lateral continuity

  ⑪ fault-bounded-grabens, half-grabens strike-slip fault-bounded basins

  ⑫ associated w/ eolian, lacustrine, marine facies

  ⑬ containing soil profiles and terrace surfaces

  ⑭ Paleocurrent patterns-radiating outward, complex, radiating patterns

  ⑮ sieve deposits

2. Fluvial(하성환경)

    경사에 따른 분류┌ Straight

                           │ Fluvial

                           └ Meandering

                            * Anastomosing

    평면도 - meandering

              - crevasse - splay

              - point bar

              - levee

              - flood plain

     Channel migration

                  Point bar sequence - fining-upward

     Sediment ┌ Various Characters

                  └ red color, cross-bedding, 토양층(calcrete)

     Fossil - fish, gastropods, pelecypods, trails on flood plains, plant, pollen

     Paleocurrent - imbrication, cross-bedding

     Process   - normal, gravity(debris flow, stream flood, sheet flood)

     ┌ Sand dominated - Trollheim, Scott, Donjek type

     └ Gravel dominated - Sask atchewan, platte, Bijou type (p.246)

     Climate, regional geology, geomorphology, relief, discharge, substrate composition

       ==> controlling factors for fluvial sedimentary facies

  1) Braided channel

      a. 특징 : 1. numerous channel separated by bars, small islands

                   2. low sinuosity, coarse sediments w/ bedload, suspended load

                   3. deposition : shifting of channels and bar aggradation

                   4. steep slope, bankful discharge

                   5. overloaded channel로 불림

      b. process

         1. fan(humid)의 distal part와 유사한 process를 보임

         2. temporal variation in discharge --> coarser grains를 계속 운반할 수 없음

      c. sediment and sedimentary structures

         1. planar, trough cross-stratified, massive

         2. crudely-bedded gravel facies, matrix-supported

         3. small lenses of sand, mud w/ ripple, imbrication of pebble

         4. sediment bodies : longitudinal bars(linguoid bars)

  2) Meandering channel

     ① two types - coarser grained meander belt : sand gravel.

                          fine-grained meander belt : highly sinuous

     ② lateral accretion : fining-upward(point-bar)

     ③ flow velocity variation through depth

     ④ deposits : channel lags

         point-bar deposits - scroll bars, swale, well-sorted, pebbles-common

         channel sequence - regular, cyclic sequence

         overbank deposits : natural levee-coarser

                                      flood plain - finer

         crevass-splay - coarser than levee deposits, locally, fan-shaped

         channel-fill deposit : abandoned organic-rich

주요 facies 특성 요약:

 ⓐ fluvial sands range from very coarse, through fine to medium-grained

     well-sorted examples to silty or muddy sands

 ⓑ channel, point bar, braided bar sands-well-sorted, cyclicity

 ⓒ electric log - fining-upwards

 ⓓ trough cross-bedding, planar cross-bedding

 ⓔ meandering channel - cross - stratification

 ⓕ oxidizing environments - red colors

 ⓖ paleontology- ① very restricted - fish, gastropods, pelecypods, trails on floodplains

                        ② most common-plant fossils-large logs, plant debris, fossil pollen

                           ┌ large amount of pollen        ┐ confirm fluvial facies

                           └ lack of marine microfossils ┘

 ⓗ paleocurrent structures : imbrication, cross-bedding

 ⓘ braided river : sheet or wedge-shaped sandstone, conglomerate w/thin, persistent

                         shale enclosed within coarser sediments

                         great thickness(〉200m) clast-supported gravels from channels and bars

                         (long axes transverse to flow)

 ⓙ meandering river :   confined by abandoned mud-filled meander loops(oxbow lakes)

                                 liner or shoestring sand body down the depositional slope

                                 sand body commonly

 ⓚ anastomosing river : peaty silts are dominant

                                  sand or gravel bodies are very marrow to the thickness

 ⓛ braided rivers

    ① ┌ inter mediate axis :upstream imbricated ┐↔deep sea conglomerate

        └ long axis : transverse to flow               ┘  (long axis : imbricate and  paralleled w/ flow)

    ② no cylicity

    ③┌ trough, tabular crossbeds by migration of gravelly dunes

       └ or flat topped bars, horizontal bed

    ④ rough fining-upward sequences

    ⑤ from base to top

        horizontally bedded or cross-stratified→roughly cross-stratified gravelly sand

           →irregular sandy tabular crossbed sets or parallel laminations and

           capped by fine-grained rippled sand and muds

    ⑥ ** Planar tabular crossbed sets within sand body

            → Briaided nature of the sequence

             * more irregularities in grain size trends, less fine overbank material

 ⓜ meandering rivers

    ① floodplain deposits-muds containing roots or caliches

    ② classic fining-upward sequences : by lateral river

        migration : lag gravel→intraclast conglomerate→sand→mud

 ⓝ anastomosing rivers:

    ①thick peat-rich silts and clays laterally to coarse grained channel facies

    ② little fining-upward sequence

3. Aeolian or Desert (풍성환경)

   Dune - interdune + dune (well sorted, rounded, generally fine-to-medium supermature sand size)

   Wadis- imtermittent streams

   Barchan - 초승달모양 사구

   Seif - longitudinal 사구

   대개 Playa, Subhka 와 연결되어 있음

   기후 - hot & dry(250mm이하/year) : 20% 의 사막 : dune-covered

   현생 - Basin and Range of U.S.A on active tectonic setting

            Sahara 사막 of the stable craton

   Erg - 모래로 덮인 사막

   Pediments - 기반암이 노출되어 있는 사막

   Desert Pavement - deflation, mud crack, residual(lag) coarse grains

   Loess: 사막에서 기원한 이질 퇴적물 (황사)

   Draas - extremely large bed forms with l km 이상 wavelength

   Dreikanters - 삼릉석 - deflation pavement

   Sediments -  large scale cross-bedding

                      raindrop imprints

                      bimodal sand lag

                      clay coating (hematite coating)

                      tabular beds

                      quartz(most) feldspar(mineral)

                      Not much fossils- pollens, spores some algae

주요 facies 특성 요약:

 ⓐ large-scale(tabular wedge), planar cross-strata(dip : 20-30°)

     overlain by smaller scale trough cross-strata(climbing ripples)

 ⓑ sand flow toes, forming tangential contact of cross-beds w/ lower bounding surface

 ⓒ raindrop imprints (raised rim, depressed centers)

 ⓓ evenly distributed bimodal sand lags along erosional surfaces

 ⓔ high ripple index : oriented up and down leeside deposits & desiccation cracks

 ⓕ graded deposits, probably related to grain fall processes

     inverse graded produced by migrating ripples

 ⓖ Texture : ① moderately sorted to well-sorted, fine-to medium-grained inland dune sand

                      rounded, generally supermature

                  ② well-sorted fine-grained coastal dune sand

                  ③ moderately to very poorly sorted interdune or serir(stony desert) sands

                  ④ rapid textural change and permeability contrasts on a bed within cross-bed sets

                  ⑤ many eolian sand grains have clay coatings probably responsible for the reddening of                       dune sand

 ⓗ geometry : tabular bodies

     composition : quartz, feldspar

 ⓘ not much paleontology pollen & spores, some algal -common

4. Lacustrine (호성환경)

    현재 지표면의 1% 차지 - 호수,  60%의 호수 : freshwater → limnology(호수학)

    분류기준 : climate - 열대, 온대, 한대

                    sediment type ┌ biochemical

                                        └ terrigenous

      Swamp : tree

      Marsh : grass

      Bog : peat

    Oligtrophic : few nutrients, low productivity

      Eutrophic : high nutrients, high productivity, oxygen deficient in the hypolimnion

    Annual circulation patterns

      ① temperature driven: once or twice overturn in a year

         ┌ spring overturn

         └ fall overturn

      ② density driven:  influx of suspended sediment ┐ → overflow  ┐

                                             of cold water           ┘ interflow      │로 분리

                                                                                 underflow ┘

      ③ upwelling and sinking

            - wind blowing across the epilimnion

  * Lake sediments : Fig 5-16

     수평적 퇴적상 배열 순서 alluvial fan → mud flat →interdeltaic marginal lacustrine →open lacustrine

     mostly thin : (200m 〉 ), cirular in plan view, lenticular

     terrigenous sediment - river input

        - a single, large source of sediment → delta (coarsening-upward sequence)

        - pelagic sediment - silt, mud(clay) through settling from suspension (varve structure)

        - turbidite : cold runoff + dense turbid water → underflows or turbidity currents

     chemical sediments - saline lake : 5‰ 이상 dissolved solids.

                                      carbonate lake

        - saline lakes = SiO2, Ca2+, Mg2+, Na+, K+, HCO3-, CO32-, SO42-, (Playa, Sabkha) Cl-

        - 정출 순서: CaCO3 → Dologmite, CaMg(CO3)2 → Gypsum(CaSO4, 2H2O),

           Anhydrite(CaSO4) → Halite(NaCl)  →  Potash salts → Bittern salts

                                                                └── Playa lakes only ──┘

     biogenic sediments - pelecypods, gastropods, diatoms, oncolite-blue green algae + detrital                                      nucleus

     chemical sediment - pyrites

         * Marl - typical of freshwater lake sediment (calcareous + detrital mud)

 기타 특징

    1. fining-outward

   2. coarsening-upward as the basin fills

   3. thin, continuous bedding varves

   4. diverse paleontology - algae, mulluscs, ostracods, vertebrate,

   5. 석유 근원암 역할: 미국 Utah의 Uinta 분지, 중국 서부 - Qaidam Pendi 유전

 주요 facies 특성 요약:

  ⓐ common fossils : aquatic vertebrates, ostracods, palynomorphs, mollusks, bivalves, gastropods,                                charophytes(blue green algae), diatoms, algae, plants,

                               conchostracans(brachiopods), burrowing

  ⓑ abundant lipid-rich organic sediment, horizontally laminated

  ⓒ even and continuous varve-like laminae

  ⓓ polygonal pull-apart or desiccation cracks, bird tracks(trace fossils)

  ⓔ loop-bedding : disrupted thin beds and laminae broken by low-and

      high-angle, small-scale fault and boudinage pull-apart structures.

  ⓕ salt-crystal molds in nodular chert, mud-supported carbonate rock

      -'lumpy' texture or wavy, irregular bedding

  ⓖ Graded Bouma sequence of thin bedded sandstone and interbedded mudstone

      including sole mark, rip-up clast, burrowing, ripple mark

  ⓗ desiccated algal mats and crusts of evaporite minerals,

      fossiliferous coal bed w/mullusk wackstone

  ⓘ low-angle cross-strata, interbedded sandstone w/ mollusk-bearing mudstone.

  ⓙ climbing-ripple lamination, cross-laminated sandstone and siltstone beds

  ⓚ Burrowed rock(bioturbation) w flat bedded sandstone underlying coal and lime wackestone

  ⓛ sandstone grading upward from large-scale, low=angle tabular to trough cross-strata

      near base to medium-scale trough cross-strata to small-scale cross lamination

  ⓜ stromatolitic algal boundstone overlain by an ostracods,

      curviplanar, laminated to small-scale cross-laminated calcareous sandstone

  ⓝ ① some what circular in plan view and lenticular in cross-section

      ② fining-outward trend into the basin and coarsening-upward stratigraphic trend

      ③ marl, evaporite minerals some zeolite mineral especially analcime

      ④ thin continuous bed(varve) small ripple and ripple cross-strata

5. Glacial (빙하환경)

   - Restricted by latitude, elevation

        cirque glacier (산정에 국한)

        valley glacier (mountain or alpine glaciers)

        continental glacier (ice sheet)

   - Plastic behavior at depth

   - Rate of movement : a few to 100 meter per year

                                 slide over the bed rock surface (50 %) + ice itself flow (50%)

 * Erosion

   - glacial striation and glacial groove by sediment-laden ice, crescentic gouge

   - polish or smoothed surface by fine-grained sediment at the base of the ice mass

 * Deposition : characteristics : sorting, grain size, particle shape, fabric, lithologic composition size                                              and geometry of the unit.

   - lateral moraine(측퇴석), terminal moraine(종퇴석)

   - subglacial sedimentation: 빙하 하부에 포함되어 운반

   - englacial sedimentation : within the ice mass

   - proglacial sedimentation : in front of the glacial termination and by discharging meltwater

   - drift (glacial-deposited sediments.)

    ┌ till → unsorted, unstratified, fine-matrix → tillite, polymictic conglomerate(diamictite)

    └ outwash deposits → sand, gravel w/ silt, clay

   - 호주의 Cooper 분지, Oman의 Marshal Field 에서는 fluvial, lacustrine 환경과 연계되어 석유 산출

 주요 facies 특성 요약:

  ⓐ similar deposits to fluvial, unidirectiontional flow structures

  ⓑ abrupt particle change

  ⓒ very poor sorting - pebble, cobble size, coarse grain

  ⓓ well-imbrication to upstream dips

  ⓔ gravel bars, transverse ribs or clast stripes

  ⓕ large-scale cross-bedding antidune and standing wave structures some ripples and

      megaripples, structureless for drift sediments

  ⓖ geometry : tabular or linear

      composition : heterogeneous

  ⓗ pollen, spore - Pleistocene deposits

  ⓘ 주요 퇴적 시기 - Precambrian(middle-late),

          Carboniferous-Permian(Gondwana)-Africa, India, Australia, Antarctic, South America

6. Delta (삼각주 환경)

     - 3 main parts - delta plain, delta front, prodelta

   1. interaction between sediment yield and energy flux.

   2. large delta in trailing-edge coast and marginal sea coasts

   3. constructional phase - progradational, river-dominated

       destructional phase - wave, currents, tidal dominated

   4. deltaic process의 주요 지배 변수

      주변수 - riverine processes

      종변수 - climate, relief in the drain age basin, sediment yield, water discharge regime

   5. three primary forcess in riverine process

       - inertial forces - homopycnal - no density contrast between river and sea water

                               (turbulent jet)

       - bed friction

       - buoyancy

     ① inertia-dominated effluent

         Gilbert's delta model : topset, foreset, bottomset.

         (deep lake or where tide homogenizes the water mass) ← high gradient streams

     ② bed friction - dominated outflow

                         - bifurcation of the outflow

                         - substantial shoaling just behind the mouth

                         - lateral spreading - homopycnal flow

     ③ buoyant outflow

         density contrast ┌ fresh water : 1.0

                                └ sea water : 1.026～1.028 g/㎤

                                     hypopycnal flow

   6. marine processes

     ① tide - Amazon, Gangls-Brahmaputra(bangladesh) Ord(Australia)

                 linear shoals with their long axes parallel to flow

     ② wave - broad, gently-sloping shelves → well-developed deltas

     ③ coastal currents - channel mouth migration을 초래 sand spit

   7. deltaic sediments

     ① distributary channel  - coarsest sediment

                                         migrating laterally - X - bedding

                                         abandoned channel filled w/ mixed. silt, clay, organic material

         natural levee - subaerial or subaqueous

                                 fine-grained settling from suspension

     ② interdistributary bays and marshes - most silt and clay

                                                             scattered shell debris, thin sand lenses,

                                                             parallel laminations and burrow mottling

     ③ mud lumps - diapiric masses of deformed muds

                           (3～4m above sea-level)

     ④ delta front : depth - ~10m or less

                                     sand-sized sediment-by winnowing

                                     X-stratification, low bioturbation

                                     highest energy environments

                                     progradation - common

                                     elongate or crescentic sand bodies

           * distal bar : near outer limits of the delta front

                              interbedded fine sand and mud

                              several meter high

                              rotational slump blocks

     ⑤ prodelta - widespread & homogeneous silt & clay

                       fining-seaward

                       grade into shelf mud

                       deposition from suspension → thin lamination

                       shell-scattered

                                   ──────→ fluvial process

           * straind plain → cuspate → lobate → elongate

                                  ←────── marine process

           * size : few 1000 ㎢ - area

                       few 1000m - thick

 주요 facies 특성 요약:

  ⓐ geometry : thick lens, wedge

      Texture : coarsening-upward trend, sand and mud

  ⓑ lithology : coal and peat seams, abundant micaceous particles, numerous woad fibers

  ⓒ sedimentary structures: convolate bedding, diapiric features, loading structures (slump, growth       fault structure)

  ⓓ freshwater-brackish water-saltwater transition on paleontology

  ⓔ ① distal marine & destructional phase : mud & silt : gray, black

                       pyritic nodules, ironstone concretions, plant fossils,

                       marine limestone, black, hard, fissile 'slaty'

                       containing large black spheroidal concretions

      ② delta slope & prodelta : muds and silts gray

                       sandy, marine fossils, ironstone concretions

      ③ alluvial plain     ┐  sandstone, fine-grained, micaceous, siltstone

          distributary and │ argillaceous : variable massive to thin-bedded

          barrier channel ┘ usually w/an uneven lower surface

        (proximal-prograding delta) irregular bedding and burrowed structure, contorted bedding,

                                              climbing ripples

      ④ delta plain (swamp and marsh over bank and levee)

             : silt and mud, coal, underclay, gray to dark gray, noncalcareous-argillaceous occurs in

               nodules or discontinuous bed

          non-fossiliferous, sand shale : gray

  ⓕ growth fault(rollover structure) from seismic record in the subaqueous delta plain

7. Tidal flat or intertidal (조간대 환경)

  1. ┌ flood tide : 밀물 (high tide)

     └ ebb tide : 썰물 (low tide)

     ┌ spring tide : 사리

     └ neap tide : 조금

      - macrotidal - tidal range 4m 이상, mesotidal: 2-4m, microtidal: 2m 이내

  2. supratidal - intertidal - subtidal

      └─  peritidal  ─┘

  3. salt marsh - grass vegetation, mangrove(swamps) including levee, tidal creek, low relief

       sediment - mixture of fine mud and plant debris

        w/ small amount of shell material, sand, large plant fragment

        ⇒ supply by runoff of land washover of barriers & shelf

       sea-level rise → extend marsh by providing renewed sites for sediment accumulation and related

        colonization by vegetation (coarsening-upward sequence))

       sea-level fall → marsh decreases due to being high and dry (finig-upward sequence)

       character : - well-bedded w/ wavy undulations

                        - severe bioturbation

                        - small channel - fill structure

                        - marine or brackish organism

  4. mangrove swamp - tropical region peat low current and wave energy

  5. sediments - terrigenous mud+sand

                      (예: 한국 황해 조간대 - 최대 25km wide, lower relief,

                             flood current(120cm/sec) > ebb current(70cm/sec))

     ① bioturbation, burrows pelletization, herring-bone-cross-bedding

         flaser, lenticular bedding, desiccation cracks. wrinkled algal mats.

         * time - velocity asymmetry → development of reactivation surfaces.

     ②  sand-dominated - meso-tidal, macro-tidal, muddy-widespread

           ┌ low tidal flat - sand 우세, ripple mark, long wave action and winnowing의 결과

               mid tidal flat - bed load + suspension load 즉 sand와 mud의 교호층, starved ripple

           └ high tiddal flat - mud 우세

            - cross-bedding by migration of megaripples by sand waves

               tidal current in macro tidal area

  - 기타 특징:  tectonic setting - move extensive on broad stable coast

                         shape          - tabular, perpendicular to the paleo-shoreline orientation

                       thickness      - few meters

                        texture          - fining-upward sequence by progradation thin bedding

 주요 facies 특성 요약:

  ⓐ geometry : tabular or elongate, few meters in total thickness(thin-bedded)

  ⓑ texture : general fining-upward by progradation of a decrease in grain size from low tide to high                    tide

  ⓒ lithology : terrigenous tidal flat-quartz, feldspar, rock fragments, clay minerals

                    carbonate tidal flat-biogenic calcite, aragonite debris some dolomite

                    marshes : plant debris, clastic particles w/ some biogenic carbonate

  ⓓ sediment structure :

                             ┌ marsh : thin bedding various bioterbation by roots,

                             │            invertebrates burrows

                             │ terrigenous flat :

       microtrough     │    ① various bioturbation by mollusks, worms, ripple bedding

  ripple stratification │    ② common small-scale ripple X-stratification, flaser

     scour base w/   │        bedding wavy

  coarse lag, shells │        bedding. lenticular bedding channel bottom layered w/

                             │        eroded shells

                             │    ③ desiccation features in the muds. isolated sand and mud

                             │        filled

                             │        channels w/ longitudinal oblique beds

                             └ carbonate tidal flat : similar terrigenous, but w/ less physical

                                                              structures algal mats are common in ther

                                                              upper supratidal portion

  ⓔ paleontology : abundant & relatively diverse

     ┌ marsh : much plant material as peat or coal oysters and burrows of  crabs and worms

     └ tidal flat : some scattered plant debris in the upper strata, iron oxide

                       cement various burrow structures, gastropals, pelecypods

  ⓕ overlying sand, X-stratified tidal delta or subtidal esturine deposits

  ⓖ tidal channel deposits

     ┌ clean, well-sorted, very fine grained, nearly uniform grain size

     │ small and medium, scale high-angle cross-beds

     └ burrows rare, some opposed. X-bedding directions

     ┌ reworked skeletal fragments of contemporaneous shallow marine fossils

     └ many fragments oolitically coated, some well-preserved

     ┌ Elongate, sharp and erosional at sides and bases,

     └ possibly interbedded with oolitic limestones

      shoreline : ┌ gradational contact, conformably overlies oolitic limestone,

                    : └ grade upwards into tidal flat, horizontal lamination w/ s-scale

                          X-lamination. burrows rare, festoon X-beds