panduan lingkungan endap

7/16/2019 panduan lingkungan endap

1/13

52

INTERPRETASI LINGKUNGAN PENGENDAPAN

Lingkungan pengendapan dapat diinterpretasikan dari:1. Geometri dan distribusi depositional unit2. Struktur sedimen dan asosiasi litologi3. Asosiasi fosilnya

Foraminifera sebagai indikator paleoenvironmentMicrofossils in general, and forams in particular, can be used to discriminate broad marine environments in anumber of ways:

a. Quantitative: Species diversity (i.e. alpha index), M-R-T Ternary diagram, similarity, dominance:

- Diversity, ( Fisher plot :)Species richness (diversity) of foram assemblagesis known to vary considerably depending onsalinity, temperature, substrate etc. By plotting thenumber of species against the number ofindividual forams on a logarithmic scale, you get ameasure of diversity called the (a= alpha) valuefor the assemblage (see Murray 1973): In general,values of a < 5 indicate brackish or hypersaline

marginal marineenvironments (though it mayalso indicate normal marine conditions with a highdominance of a single species). Where a > 7 (upto 25 or more), normal marine shelf to slope orhypersaline shelfare indicated.

- Wall structure ( Miliolid-Rotalia-Textulariina/Agglutinated Ternary diagram)Although there is some overlap of environments,this type of analysis is particularly useful fordiscriminating shallow-water environments.

The porcelaneous component exceeds 20%

only in normal marine and hypersalinelagoon and marshes and is normally < 20% in shelf areas.

Agglutinated forms dominate in brackish and

abyssal zones (below CCD).

-.Test form and the environmentTest form in benthic foraminifera is a compromise between a complex array of selective pressures, but it istrue that there is often a good correlation between form of the test and the environment in which the foramlives.

Hypersaline and brackish environments exhibit a smaller range of morphological variety (dominated

by planispiral, trochospiral, miliolid and annular tests). Uniserial, biserial and fusiform tests aregenerally absent in these environments.

Uniserial tests generally only occur in low energy zones associated with shelf, slope and bathyal

environments.

Milioline tests are mainly found on the shelf, and rarely found in slope and deep sea environments

Agglutinated foraminifera can be classified into four morphogroups and these have a distinctive distributionin modern environments:

"


2/13

Morphogroup A (unilocular, tubular or

branching) are characteristic of thedeep sea.

Morphogroups B1 (globular) & B2 (coiled -

flattened) represent only a small % inmost assemblages but they are morecommon in deeper waterenvironments

Morphogroup B3 (multilocular,planispiral/trochospiral, lenticular) areparticularly common in shelf andmarginal marine environments.

Morphogroup C1 (elongate) is absent in

marsh and lagoon environments, butcan dominate shelf and upper bathyal(to 1000 m) environments

Morphogroups C2 (elongate

quinqueloculine) and D (trochospiralconical) are characteristic of marshes andlagoons.

b. Characteristic foraminiferal assemblagesModern and ancient environments (from marginal marine to abyssal) can also be identified based oncharateristic foraminiferal assemblages (i.e. the biotope concept). Identification of these characteristicassemblages is obviously dependent of specialist taxonomic knowledge (at least to genus level).

Interpretasi berdasarkan asosiasi mikrofosil foraminifera, harus didasarkan atas keseluruhan dariasosiasi foraminieranya. Interpretasi tersebut harus didasarkan ciri-ciri keseluruhan sepertibagaimana kehadiran (persentasi) plangtonik, milolid, arenaceous form, foram besar dan tentunyajuga asosiasi calcareous bentoniknya. selain itu harus diperhatikan pula kelimpahan dankeragamanya, apakah ada dominasi fauna tertentu (misal. genus tertentu, kelompok tertentu (misal

kelompok miliolid, arenaceous atau foram besar), preservasi, ukuran dan bentuk test dll.

Berikut ini adalah penjelasan singkat, sebagai dasar dalam menginterpretasi lingkungan pengendapanberadasarkan asosiasi formainiferanya (diambil dari Rawenda dkk, 1983. Robertson Research Indonesia)

ECOLOGY OF RECENT FORAMINIFERAThe distribution of foraminiferal taxa is influenced by many different factors. Although many authorsconsider water depth the most significant one, water depth specifically is not the main variable, thecontrolling factors being the various physical and chemical conditions associated with depth. Typical factorsare temperature and temperature variability, light availability, sedimentation rate, bottom characters, energyconditions and pressure.

Studies of recent foraminiferal ecology have provided numerous distinct criteria by which many depositionalenvironments can be characterised and which can be applied to fossil assemblages from sedimentary rocks.Some of the main variables can be summarised as follows:

1. The total number of species and of individuals increases away from the shoreline, and withincreasing depth of water, to maximum values on the outer shelf and in the upper bathyal zone.

2. Porcelaneous forms show their present diversity in shallow, nearshore environments.3. Arenaceous foraminifers with simple interior wall structure become dominant in shallow waters

or in intertidal areas. The percentage occurrence of these arenaceous forms reaches amaximum near the effluence of rivers.

4. Calcareous foraminiferal tests become smaller and thinner near sources of fresh water. Incarbonate rich environments, tests may reach a large size and be very robust.

5. The percentage occurrence of the most common species in a foraminiferal population relates tothe variability of the environment. As marginal marine conditions are approached,environmental parameters become more pronounced resulting in a tendency towards singlespecies dominance in the most unfavourable environments.

6. Planktonic forms occur most abundantly within the outer shelf and deeper water. Under idealsedimentation contitions, especially in clastic deposit, planktonic foraminifers can show a moreor less regular increase in abundance with depth.

53

53


3/13

7. Arenaceous taxa with labyrinthic wall structures occurs most abundantly in bathyal or deeperwaters. In sediments deposited below the calcium carbonate compensation depth (CCD) theseforms may become dominant since the calcareous shells of other foraminifers are dissolved.

INTERPRETATION OF SEDiMENTARY ENTVIROMENTS ON THE BASIS OF MODERNFORAMINIFERAL DISTRIBUTIONS

The following is a brief summary of how specific depositional environments may be recognised by means oftheir foraminiferal content.

1. Non-marine (supralittoral) environments e.g. delta top, alluvial plain.These environments are barren offoraminifers. Palynological analysis is essential to obtain a detailed interpretation.

2. Transitional environments (marginal marine, littoral, intertidal)brackish water. Again palynological studiesare of major importance in assessing these environments. The following subdivision of these environmentsand their faunal characteristics can be made.

2a. Sandy beachesThe microfauna inhabiting this environment is little diagnostic. The species diversity is low, and planktonic,larger foraminiferal and attached calcareous benthonic forms are absent. As most high energy sandybeaches face open sea, salinities are generally normal.:

Characteristic species areQuinquetoculina sp.Miliolinella sp,Ammonia beccariiElphidium spp.

Fossil sandy beaches can be recognised by poorly preserved abraded specimens. However, due tocontinuous transport of the tests after death many small or thin-shelled specimens may be destroyed, andforaminifers are sometimes completely absent from an exposed beach sand. A further complication indetermining an ancient sandy beach is, that many alochnous forms may have been washed in.

2b. Marshes and, mangrove swampsTidal marshes and mangrove swamps represent transitional regions between marine/brackish water and

terrestrial environments. Tidal marshes occur in temperate areas, whereas the mangrove swamp ischaracteristic for the tropics.

Tidal marshes can be subdivided in three groups according to salinity:1)Hyposaline marshes2)Normal marine marshes ) difficult to distinguish3)Hypersaline marshes

Species diversity is highest in hyposaline marshes, although the general diversity is low. The hyposalinemarshes are characterised by the predominance of arenaceous species (Miliammina sp., Ammotiurn sp.,Trochammina inflata) and rotalids (Elphidium spp.) and the absence of miliolids.

Normal marine marshes are inhabited by dominantly arenaceous species with minor miliolids

(Quinqueloculina) and rotalids (Elphidium spp.,Ammonia beccarii).

In hypersaline marshes the percentage of arenaceous species, miliolids and rotalids is about equal. Typicalcosmopolitan marsh species are:

Ammotium salsumAreno parrella mexicanaMiliammina fuscaTrochammina macrescensT. polystoma

Interpreting an ancient marsh environment may be difficult. Due to reducing conditions calcareous tests areeasily destroyed after death. After complete solution of calcareous species, it is impossible to distinguish

between the various marsh environments. Only the low.diversity and an assemblage consisting of smallarenaceous species such as Trochammina sp. , Haplophragmoides sp., Amobaculites sp. points to a marshorigin. IfMiliammina sp. is present in this assemblage, a hyposaline lagoon could also be indicated

54


4/13

The lithology of a marsh deposit consists of dark grey highly organic clay and silt, containing abundant rootsand other in determining an ancient plant debris. This can often help marsh deposit. Pyrite is common, dueto the reducing conditions.

Faunal distribution in a mangrove swamp is similar to that of marshes. Typical taxa in a Southeast Asianmangrove are as follows:

Haplophragmoides salsunHaplophragmoides wilbertiMiliammina pariaensisArenoparella mexicanaTrochammina laevigata

2c. Tidal flatsTidal flats develop along gently dipping sea coasts, with marked tidal rhythms, where enough sediment isavailable and strong wave action is not present. This may be the case in estuaries, lagoons, bays, or behindbarrier islands or other sand bars.

Characteristic foraminifers inhabiting this environment are:Ammonia beccariiElphidiun spp.(Quinqueloculina sp.)

Rotalids predominate in tidal flat assemblages, miliolids are rare to absent, and arenaceous species notcommon.

2d. EstuariesAn estuary is the wide mouth of a river or arm of.the sea where the tide meets the river currents, or flowsand ebbs.

Estuaries are hyposaline in character, and can be subdivided into an upper part, subject to the greatestfreshwater influence and a lower part connected with the sea. This differences in salinity is reflectedinthefaunas of both parts:

upper estuary lower estuaryMiliammina sp. Miliammina sp.Amobaculitessp. Ammobaculites sp.

Ammonia beccariiElphidiun spp.

2e. LagoonsA lagoon is a shallow lake or sheet of water, connected with the sea or a river. Coastal lagoons are shallowwater bodies, running parallel to the coast, and connected to the sea with an outlet. They are separatedfrom the sea by sand bars or barrier islands.

Based on the amount of seawater entering through the inlet, and the amount of freshwater contributed byriver, the following subdivision of lagoons can be made:

a) hyposaline : freshwater seawaterb) normal marine lagoonsc) hypersaline : no freshwater comes into the lagoons

A characteristic feature of modern lagoons is their low foraminiferal species-diversity. The relatively highestdiversity is found in normal marine lagoons. Despite the fact that literature on lagoonal assemblages isscarce, the following genera to some extent may characterise the three types:

55

55


5/13

Genus Hyposaline Normal marine HypersalineAmmotium xxxMillammina fusca xxx Quinqueloculina xxx xxxTriloculina xxx xxxMiliolinella xxx xxxPeneroptids xxx xxxGlabratella xxx xxxAmmonia beccarii xxx xxx xxxElphidium xxx xxx xxxProtelphidium xxx xxx

2f. DeltasWith respect to foraminiferal assemblages deltas require special comments since in these environmentscertain species behave abnormally,especially within the prodelta region.

Three major environmental systems can be distinguished within a delta as follows:

A) The delta plainThe delta plain consists of an intertidal or supratidal covered with Nipah and mangrove vegetation.Palynological studies are most useful in assessing delta top environments.

B)The delta frontThe delta front consists of an intertidal to shallow subtidal platform fringing the delta plain. The inner zone ofthe delta front consists of extensive tidal flats. Foraminiferal assemblages relate to local sub-envirormentswhich have already been discussed under 2a-e.

C) ProdeltaThe prodelta consists -of the smooth, steep slope seaward of the edge of the delta front platform, marked byan abrupt slope break at the 5 meter isobath. The outer limit of the prodelta appears to coincide with the 60-70m,isobath.

It is important to mention the "delta effect" (e.g. Pflum & Frerichs, 1976), that is,a variable upper depth limitof certain species. They call these species heterobathyal species, as opposed to isobathyal species (whichhave a more or less consistant upper depth limit). It is possible to distinguish delta elevated and delta

depressed species. Delta elevated species are species with a shallower upper depth limit in the delta area.(For instance Sigmoilopsis schlwnbergeri and Martinotiella occidentalis). Delta depressed species have alower upper depth limit in a delta area. Examples are Pullenia quinqueloba, Melonls barleeanus, Hoglundinaelegans and Bulimina aculeata.

However care must be taken in applying these data to ancient environments.

3. Marine Environments

A widely used tool for distinguishin- marine environments is the planktonic/benthonic ratio. In general it isbelieved that increasindepth will imply an increase in the percentage of planktonic species. The system wasdeveloped initially by Grimsdale and van Morkhoven (1955) who found that it lacked the precision that theyhad hoped for. They suggested the following relationship:

Environment Depth in Ifeters % Pelagic/Benthonic Ratio

Inner Shelf 0- 20m 0-20%Middle Shelf 20- 100m 20-50%Outer Shelf 100- 200M 20-50%Upper Slope 200-1000m 30-80'/7.Lower Slope 1000-4000m 70-100%

However, it is extremely dangerous to rely on the planktonic percentage alone. In a case of 90% planktonicsfor instance, it is important to determine how many planktonic species are present, if there are only a few,the environment may be quite shallow. It is also important to note size sorting.

Bearing these points in mind, and also noting the distribution of calcareous benthonic, arenaceous and largerforaminifers the following marine environments may be characterised:

56


6/13

3a.Inner Shelf (low tide -20m) inner neritic, shallow inner sublittoral.

This environment has its lower boundary at the base of the turbulent zone. Within this depth range manysub-environments can be recognised, depending on wave energy, substratum etc., and hence many differentpopulations can be found. Characteristic for inner shelf environments is the low species diversity, with oneor two species dominating the faunas. Planktonic foraminifers may occur in frequencies of 0-20%. Largerforaminifera such as Operculina and Amphistegina may be locally abundant, other forms may be abundantonly in carbonate sediments.

The following taxa are typical of inner shelf environments. It must be stressed that this is not a complete listand that the taxa indicated are not restricted to this environment.

Southeast AsiaPlanorbulinella sp. Chrysalidinella limbatumMassilina sp. Asterorotatia spp.Cibicides tobatulus Cymbaloporetta squamosaPseudorotatia spp. Bacutogypsina sphaerulataCellan thus craticulatus Amphistegina lessonii Loxostom limbatum Ammonia spp.Elphidium spp.

3b. Middle Shelf (20-100m), middle neritic, inner sublittoral

The middle shelf can be subdivided in two parts:1) Shallow middle shelf (20-50m). The lower boundary of this zone is the base of the photic zone

and the storm wave base.2) Deep middle shelf (50-100m). The lower boundary of this zone is the base of the seasonal

temperature changes.

Shallow Middle ShelfThe diversity of species increases here. Larger foraminiferal species (opercuzina spp. and Amphisteginaspp. particularly A. quoyiare common to abundant locally, and the same calcareous benthic assemblage ofthe inner shelf is present, but their tests are generally more robust.

Planktonic foraminifers can make up 20-30% of the total assemblages, but their diversity is low, and

restricted to forms such as Globigerinoides spp. and Globigerina bulloides.

Deep Middle ShelfRich assemblages are generally present in this environment. 'The typical inhabitants of the inner andshallow middle shelf are still present , but they are rare (Operculina spp., Amphistegina spp., Elphidumspp ., Pseudorotatia spp .) -Planktonic foraminifers can make up to :40-50% of the total assemblages.

Typical middle shelf taxa in Southeast Asia are as follows:

Operculina spp. Baggina inflataAmphistegina spp.(A. bicirculata and A. papillosa) Bigenerina nodosariaBolivina spp. PraeglobobuliminapupoidesFlorilus spp. Siphonina pulchra

Anomalinella Cancris auriculusCassidulina laevigata Nodosaria spp.Cassidulina oblonga Uvigerina sppHeterolepa praecinctus Loxostomum spp.Dentalina spp. Lenticulina spp.20-40% Planktonic foraminifers +10 species.

3c. Outer Shelf (100-200m) outer neritic, outer sublittoral

The lower boundary of this zone is the shelf edge. The species diversity in this environment is high.Planktonic foraminifera make up to 40-80% of the total assemblages and their diversity is high (moreless 20species in recent samples). Larger foraiainifera are absent. Most of the calcareous benthic species of thedeep middle shelf are present.

Typical taxa of the outer shelf are as follows:

57

57


7/13

Gyroidina acuta Pulllnia quinquezobaGyroidina soldanii Uvigerina soendaensisHoglundina elegans Bulimina striateCassidulina spp. Bulimina marginataFursenkoina spp. Sphaeroidina bulloides

Bathyal and Abyssal EnvironmentsOn most shelves the inclination of the seafloor increases at about 180-200m depth, and this correspondswith the continental slope. In the deeper waters below 200m conditions are very stable as compared toshallower environments. No major changes in temperature and salinity occur. Because of these stableconditions many of the species living in these environments will be cosmopolitan. However, with increasingdepth, the solubility of calcium carbonate will increase. The critical depth is called the calcium carbonatecompensation depth, which lies in modern oceans between 4000-5500m. Below this depth calcareous testswill be dissolved. In general, we will find with increasing depth a decrease of calcareous benthic species,and an increase in arenaceous species. An interesting factor is that the size of many deep water benthicforms shows increase with depth. Many taxa here have very specific depth limits and are termed isobathyalspecies. These are particularly helpful in determining environments.

3d. Upper slope (upper bathyal) 200m-1000m water depths

Species diversity and abundance is usually very high in this environment. The planktonic percentageincreases to 50-95%. Robust arenaceous species such as Martinotiella comminis, Karreriella sp., Tritaxilina

sp., Dorothia and Haplophragmoides sp. occur frequently.

Typical upper slope taxa are as follow:

Martinotiella communis Sphaeroidina bulloidesKarrerietLa sp. Tritaxitina sp.Pullenia bulloides Uvigerina peregrinaChilostomella oolina Gavelinopsis translucensGlobocassidulina subglobosa50-95% Planktonics

Isobathyal (-cosmopolitan) species with their highest depth limit within zone are as follows:

Bolivina albatrossiBulimina striate mexicana ) highestChilostomell,a oozina ) occurrenceEponides reguza ) at 200mGyroidina altiformis cushmani )Discorbis transluucensUvigerina peregrina

Bulimina acuzealaBuliminarostrataalazanensis ) highestOsangularia rugosa ) occurrenceUvigerina peregrina dirupta ) at 300mUvigerina peregrina mediterranea

cibicides bantconensis ) highestGyroidina orbicularis ) occurrenceReticulophragmium venezuelanum ) at 400-500mCyclammina cancellata

Cibicides kullenbergi )Cibicides rugosus )Eponides polilus ) highestOriidorsalis tener umbonatus )occurrenceOsangularia culter ) at 700 - 800 mPleurostomella bolivinoides )

3e. Lower Slope, lower bathyal (1000-4000m)Planktonic foraminifers are generally very abundant in this environment (90%). However, as the lower limitof this environment is close to the calcium carbonate compensation level, solution prone species such as

58


8/13

Orbutina sp. and Globigerinoides spp. may be absent. A conspicuous decrease of calcareous benthic formsis noted. Robust arenaceous species such as Cyclammina cancelata and Tritaxia sp. may predominate thefaunas.Typical lower slope taxa are as follows:

Mellonis pompiliolides Cyclanmina cancelataLaticarinina pauperata Cibicides wuellerstorfi Oridorsalis umbonatus Globocassidulina subglobosa90% Planktonics

Isobathyal (cosmopolitan) species with their highest'depth limit within zone are as follows:

Anomalina globulosa ) highest) occurrence

Siphotextularia rozshauseni ) at 1000-1300 m

UVigerina ampulacea ) upper depth limi t 1600mUvigerina senticosa u ) pper depth limit 2000mMelonis pompilioides ) upper depth limit 2200m

3f. Abyssal environments (4000 m and deeper)

Assemblages from this depth are generally rare and little-diverse. The calcium carbonate compensationlevel (40OOm-5500m) causes the solution of calcareous tests below this depth. Consequently, the faunasbelow 4000-5500m, will consist of large, simple arenaceous species such as Ammodiscus sp., Rhabdaminasp. and Rathysiphon sp.

Above the calcium carbonate compensation level the calcarous benthic fauna from the bathyalenvironments, and thick walled, solution resistant planktonics (Sphaeroidinellopsis sp., Globorotalia spp.) arestill present.

59

59


9/13

15. NON-FORAMA. MIKROFOSILNON FORAM(some part taken from: Pamela J. W. Gore Department of Geology, Georgia Perimeter College Clarkston,GA 30021)15.1 . PROTISTS (unicellular organisms)

A. Animal-like protistsRADIOLARIA

Geologic range: Cambrian to RecentShell composition: Silica (amorphous, opaline silica)Size: 0.1 - 2.0 mmSignificance: Useful in biostratigraphy; they accumulate to form radiolarian ooze on

the abyssal plain.Morphology: Microscopic spiny globes with large, lace-like pores, or helmet-shaped

(or space-ship shaped) with large, lace-like pores. Very transparent and glassy.Environment: Marine only; planktonic.

Radiolaria

B. Plant-like protists1. DIATOMS

Geologic range: Cretaceous to RecentShell composition: SilicaSize: Most are 0.05 - 0.02 mm (some up to 1 mm)Significance: Useful in biostratigraphy and paleoenvironmental interpretation; major

constituent of diatomite or diatomaceous earth; an integral part of the food chain(phytoplankton). Most abundant phytoplankton in the modern ocean.

Morphology: "Pillbox" shape, consisting of two valves (shells) which may be circular,triangular, or elongate. Circular forms have radial ornamentation. Elongate

forms have transverse markings. They are covered with pores.Environment: Both marine and non-marine. Planktonic or attached.

Diatoms

15.2. MULTICELLULAR ORGANISMSA. Animals

1. OSTRACODES (Phylum Arthropoda)

60

"Twenty five forms circle" prepared by K.D. Kemp, Services, Somerset, England.Photos by Bill Turner and Thom Hopen,MVA, Inc., Norcross, GA.

This image contains twenty five diatomsof various shapes which have beenassembled into the shape of a star.


10/13

Geologic range: Cambrian to Recent.Shell composition: Calcareous (some organic)Size: 0.5 - 3.0 mm (some larger)Significance: Useful in biostratigraphy and paleoenvironmental interpretation.Morphology: Microscopic shrimp-like animal inside a clam-like shell consisting of

two valves (shell halves), with a dorsal hinge.Environment: Marine and non-marine (fresh, brackish and hypersaline); most

benthic.

Ostracodes2. CONODONTS (Phylum unknown)

Geologic range: Cambrian to Late Triassic. Conodonts are extinct, and theorganism from which they came is not known with certainty.

Composition: Phosphate (calcium fluorapatite)

Size: Most are 0.5 - 1.5 mm (some up to 10 mm, and some as small as 0.1 mm)Significance: Useful in biostratigraphy and marine paleoenvironmentalinterpretation; their color is a good indicator of the temperature to which theenclosing rock has been subjected (this is important in determining whetheroil or gas may be present in the rock).

Morphology: Parts of a larger organism which resemble cone-shaped teeth, orconsisting of bars with rows of tooth-like denticles, or irregular knobby platescalledplatforms.

Environment: Marine, free-swimming.Conodonts

Images courtesy of Anita Harris, U. S. Geological Survey. 3. SPONGE SPICULES (Phylum Porifera)

Geologic range: Cambrian to RecentComposition: Calcareous or siliceousSize:Significance: Siliceous skeletons can accumulate to form chertMorphology: Shapes vary. but may be needle-like (monaxon or one axis), three-

pointed (triaxon), four-pointed (tetraxon), or shaped like a jack (from thegame of ball and jacks) with six radiating needle-like points orrays(hexactine). May also be curved.

Environment: Attached to the sea floor. Most are marine.

61

61


11/13

Sponge spicules

B. OTHER FOSSILS15.3 Algae (green algae: a,b&c Halimeda) Coralline algae

15.4 Bryozoa 15.5 Barnacles (dari Class Cirripedia)

62


12/13

15.6 Echinoid 15.7 Coral

15.8 Sepulid

15.9 Pteropod/Gastropod

15.10 Otolith15.11 Fish teeth

63

63


13/13

16. Accessory MineralsDidalam residu kadang-kadang kita menemukan adanya mineral-mineral tertentu. Kehadiran mineral-mineral tersebut penting untuk dicatat karena sangat membantu dalam interpretasi terutama interpretasilingkungan pengendapan.

16.1 Coal - mencerinkan lingkungan pada daerah yang restricted sampai transisi, bisa juga estuarine16.2 siderite - biasanya menunjukan adanya pengaruh yang kuat dari air tawar (di daerah transisi -

nonmarine).16.3 Pyrite - biasanya bila ditemukan pirit secara melimpah, akan menunjukan kondisi sedimentasi yang

anaerobic.16.4 Gypsum/anhidrite - biasanya merupakan mineral evaporite (bisa juga sebagai diagenetic mineral yang

mengisi rongga-rongga atau kekar-kekar), yang kemungkinan terjadi pada lingkungan transisi- lautdangkal

16.5 Glouconite - marine (relatif dalam: middle-outer neritic)

64