Algal-Bacterial Origin of Micrites in Mud Mounds

Tsien, H. H.

doi:10.1007/978-3-642-70355-3_23

Cited by 25 publications

(10 citation statements)

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“…Facies PM5 is also characterized by the importance of ''structure grumeleuse''. In the absence of obvious sponges, these structure are generally interpreted as microbial (cf., Pratt, 1982;Tsien, 1985). Perforations and lithoclasts show that the mats were synsedimentarily cemented.…”

Section: Sedimentological Interpretation Of Carbonate Mound Faciesmentioning

confidence: 99%

Facies architecture and diagenesis of Belgian Late Frasnian carbonate mounds

Boulvain

2001

Sedimentary Geology

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Late Frasnian Petit-Mont Member carbonate mounds occur in the southern part of the Dinant Synclinorium and in the Philippeville Anticline (SW Belgium). These mounds are 30 to 80 m thick and 100 to 250 m in diameter. They are embedded in shale, nodular shale and argillaceous limestone. Based on facies mapping of 14 buildups and related off-mound sediments, these mounds typically started from below the photic and storm wave base zones and builtup into shallow water environments. Above an argillaceous limestone substrate, the first carbonate mound facies consists of spiculitic wackestone with stromatactis (PM1), which becomes progressively enriched in crinoids and corals (PM2), then in peloids, stromatoporoids and cyanobacteria (PM3). PM4 consists of algal -coral -peloid wackestone and packstone with green algae and thick algal coatings. A core of algal and microbial bindstone (PM5) sporadically occurs within large mounds. The uppermost part of these mounds may show a recurrence of facies PM2 and PM1. PM1 to PM3 are coloured red by hematite derived from microaerophilic iron bacteria; PM4 and PM5 are grey. The transition from the aphotic to the cyanobacterial photic zone is recorded in the succession PM2 -PM3; the transition from the cyanobacterial to the green algal photic zone is recorded by PM3 -PM5. Storm wave base was reached within PM3 and fair-weather wave base within PM5. This paleobathymetric interpretation suggests a depth of 100 -150 m during initial establishment of PM1. Three types of mounds can be distinguished on the basis of geometry and facies architecture: (1) ''Les Bulants''-type mounds display a continuous vertical facies succession (PM2 -3 -4 -5) and low relief; (2) although exhibiting the same facies succession as ''Les Bulants'', ''Les Wayons''-type mounds show a distinct relief with steep flanks and bioclastic talus; (3) ''St.-Rémy'' mounds consist exclusively of PM1 and PM2, bioclastic flank deposits are not observed. From (1) to (3), these mound types represent successive deepening down a ramp. Biostratigraphic correlation on a regional scale provides good evidence that relative sea-level changes largely controlled lateral and vertical transitions of facies. Beyond that, hypoxic conditions are indicated by the sponge and iron-bacteria consortium in lower parts of the mounds. This is in agreement with the general assumption of stratified water masses during Late Frasnian, preceding the prominent Lower Kellwasser crisis. Cementation began with a radiaxial synsedimentary cement. A fringe of meteoric phreatic cement, initially nonluminescent, then with a bright orange luminescence, occurs in all mounds. It is contemporaneous with a nonluminescent pervasive cement of grainstones deposited in littoral areas. Differentiation between the (reducing) mounds and the (oxidizing) littoral area resulted from better aquifer circulation in sedimentary bodies close to the recharge area. Late burial cements occlude all the remaining porosity and are contemporaneous with the opening of the Variscan fr...

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Section: Sedimentological Interpretation Of Carbonate Mound Faciesmentioning

confidence: 99%

Facies architecture and diagenesis of Belgian Late Frasnian carbonate mounds

Boulvain

2001

Sedimentary Geology

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“…The carbonate matrix of peloidal packstones in basal laminae may represent such direct precipitation, possibly as transitional 196 intercalations of carbonate mudstonethat dominates the formativestage. Thus, the peloidsmay be productsof spontaneousor bacterially inducednucleation and lumpingofMg-calcite in the saline water column (Tsien, 1985;Chafetz, 1986;Sun and Wright, 1989;Reid and others, 1990;James and Choquette, 1990).The settingwas equatorialso thatevaporationofsurfacewaters duringarid timescouldcausesuchspontaneous, inorganic precipitation. This process, although operating in analogous locations today (see Discussion) is perhaps less likely than the following.…”

Section: Micro-laminae Note Incipient Brecciation Ofindividual Lamimentioning

confidence: 99%

Deep-basin/deep-water carbonate-evaporite deposition of a saline giant: Loch Macumber (Visean), Atlantic Canada

Schenk

Bitter

Matsumoto

1994

Carbonates Evaporites

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The Carboniferous saline giant of Atlantic Canada is approximately 500 m thick and extends over an area of 250 x 10 3 km', It consists of three lithologies: 1. a relatively thin (usually less than 5 m) extensive carbonate sheet containing buildups, 2. an overlying thick (up to 400 m) evaporite complex of sulphates and chlorides, and 3. wedge-shaped units of conglomerate, breccia, and sandstone (up to 200 m). The latter interfinger with the preceding lithologies but locally may underlie the carbonate sheet. The basal carbonate occurs mainly as fine, laminar couplets of alternating peloidal grainstones and bituminous films; these pass laterally into peloidal marlstones and mounds. Laminites andmarlstones have incipient brecciation, recumbent folds, siliciclastic and carbonate turbidites, rubble, and olistostromes.Fossils are rare. They are restricted in space to the basal decimeter and in diversity to conodonts and crustaceans. A Nereites ichnofauna occurs at one locality. Mounds consist mainly of turbid fans of fascicular-optic calcite and botryoids of laminated calcite. Their fauna shows low diversity but high density of some species; tube worms and microbial growths are noteworthy. The overlying evaporites are mainly anhydrite with lateral and vertical transition into halite and potash. Siliciclastic sediments thicken toward boundary faults. Both the base and top of the giant are unconformities, the former abrupt, the latter karsdc,The basal carbonate accumulated subaqueously in deep, physically and chemically stratified water. Initially, the desert floor of the complex rift 'basin was below ambient sea level. After catastrophic submergence, basal waters were at first dysaerobic and restricted marine, but changed to anoxic and pene-to hypersaline as the water column became stratified. Its sedimentary record corresponds to a giant, meromictic, saline lake -Loch Macumber. The laminite records either seasonal changes in rainfall and temperature, or episodic storms punctuating normal chemical sedimentation. Sulphate-reducing bacteria fed on terrestrial organic matter preserved in anoxic bottom water, and precipitated peloidal calcite. Concentrations of bacteria over hot springs may also have supported chemosynthetic organic communities and precipitated petroliferous and sulphide-rich mounds. Siliciclastic rocks increase toward basin margins. Locally steep depositional surfaces caused mass movements of sediment down basin margins. A long term increase in salinity resulted in precipitation of initially corroded and subsequently euhedral crystals of gypsum. Thick sulphates and chlorides followed. Sedimentary rock of Loch Macumber records topographic filling of a deep rift basin. Isostatic analysis suggests thatboth depth of the subaerial desert basin and initial water depth after submergence were considerably less than the preserved thickness of the saline giant. Its record corresponds closely to that expected from Schmaltz's model of deep-basin/deep-water carbonate-evaporite deposition.

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“…Because most of the rock in large cavities is dolomudstone with an average crystal size of 50 m it is reasonable to conclude that most of the original sediment consisted of mud-size grains. The original internal sediment that was the precursor of the existing dolomudstone could have been produced by biochemical or physicochemical processes, disintegration and/or abrasion of organisms, or any combination of these processes (Tsien 1985;Robbins and Blackwelder 1992). Considering that the rock in large cavities is mostly dolomudstone, and rock in flank beds and in interreef areas is entirely dolomudstone, that such rocks have the same gray color and the same average size of dolomite crystals (50 m), it is postulated that all or most of the original sediment in large cavities had a source external to the buildup.…”

Section: Processes Involved In the Formation Of Internal Sediment In mentioning

confidence: 99%

Biosedimentology of a Silurian Thrombolite Reef with Meter-Scale Growth Framework Cavities

Kahle

2001

Journal of Sedimentary Research

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A completely dolomitized Silurian reef at Maumee, Ohio, U.S.A., is uncommon among early Paleozoic reefs in that its framework consists of about 95% thrombolite boundstone and 5% corals. The reef lithified syndepositonally, as evidenced by centimeter-to meter-scale growth framework cavities within it that are completely filled with internal sediment. The largest cavities, 2-3.5 m in diameter, are probably the largest ever recorded in a thrombolite reef.Four main types of components are distinguished in the reef framework: (1) dense bushy mesoclots, (2) dense rounded to subrounded mesoclots, (3) saccate microstructures, and (4) crusts, mostly structureless, but also containing dense bushy mesoclots. The dense bushy components are abundant; rounded to sub-rounded mesoclots less so, and the remaining components are rare. The dense bushy and rounded to subrounded mesoclots are interpreted to represent the calcified remains of what were initially either aggregates of the probable filamentous cyanobacterum Angulocellularia or aggregates of renalcid calcimicrobes, or both, and the saccate mesoclots as the calcimicrobe Renalcis sensu stricto. It is speculated that syndepositonal lithification of the reef framework was accomplished by impregnation of unlithified protomesoclots by micrite to create mesoclots along with the formation of micritic cement around and between mesoclots that served to fuse together successive generations of mesoclots.The direction of branching of bushy mesoclots in the reef indicates that unlithified protomesoclots were able to grow upward, laterally, and downward. This ability, along with syndepositional lithification to create mesoclots and to cement them together, enabled the protomesoclots and mesoclots to create reef knobs and, eventually, to roof over spaces that were centimeters to three or more meters in width and height to create growth framework cavities. Features indicative of rapid deposition including graded bedding, poor sorting of bioclasts, and textural inversion are common in internal sediment in meter-size cavities. These features suggest that storms, possibly hurricanes, were at least as important, and probably more so, than ''everyday'' wave energy in transporting sediment into all cavities in the reef, regardless of size.

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Algal-Bacterial Origin of Micrites in Mud Mounds

Cited by 25 publications

References 1 publication

Facies architecture and diagenesis of Belgian Late Frasnian carbonate mounds

Facies architecture and diagenesis of Belgian Late Frasnian carbonate mounds

Deep-basin/deep-water carbonate-evaporite deposition of a saline giant: Loch Macumber (Visean), Atlantic Canada

Biosedimentology of a Silurian Thrombolite Reef with Meter-Scale Growth Framework Cavities

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