Biogenically induced bedded chert formation in the alkaline palaeo-lake of the Green River Formation

Kuma, Ryusei; Hasegawa, Hitoshi; Yamamoto, Koshi; Yoshida, Hidekazu; Whiteside, Jessica H.; Katsuta, Nagayoshi; Ikeda, Masayuki

doi:10.1038/s41598-019-52862-7

Cited by 17 publications

(4 citation statements)

References 52 publications

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“…This environment has alkaline fertile soil conditions at fertile to be overgrown by aquatic plants. The plant remains will be deposited in the water column along with the (paleo) soil, then silicified due to leaching from the volcanic material covering them [20,23].…”

Section: Discussionmentioning

confidence: 99%

The Significances of Cretaceous Petrified Wood Fossils from Padangcermin, Lampung in Paleoenvironmental Perspectives

Harbowo

Nahar²,

Sari³

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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Reports on the presences of petrified wood fossils in Padangcermin, Lampung, are rare, no strong examination that expose the scientific concern on its paleoenvironment perspective. By the published geological map, these fossils was found in the area that labelled as Cretaceous sedimentary rock (145-66 mya). Recently, the known oldest petrified wood fossil in Indonesia, is from Miocene epoch (23.03-5.33 mya). It is an interesting circumstance to examine. By this study, we are trying to confirm this circumstances by conducting the geological mapping, collecting, and identifying the petrified wood fossils that could be found as in situ fossils in the area. This study reveals a new update in paleoenvironmental perspective. The petrified woods in this area are commonly preserved in cherty layer. There are also several fossilized aquatic freshwater plant remains that presences in this area. We suggest the fossilization of the petrified wood fossil in this area is related to high alkaline-freshwater lacustrine. Supposedly, it associated with the Cretaceous terrestrial landmass and freshwater lacustrine environment in southern paleo-Sumatra by paleontological interpretation of data in this study.

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Section: Discussionmentioning

confidence: 99%

The Significances of Cretaceous Petrified Wood Fossils from Padangcermin, Lampung in Paleoenvironmental Perspectives

Harbowo

Nahar²,

Sari³

et al. 2022

IOP Conf. Ser.: Earth Environ. Sci.

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“…Biogenic CO 2 and its role in lowering silica solubility in the water column (lowering pH) and in sediments has often been invoked as a factor in formation of lacustrine cherts (e.g. Peterson & Von Der Borch, 1965; Kuma et al ., 2019). At Lake Magadi and Nasikie Engida, the influx of geothermal CO 2 along faults and fractures might also decrease silica solubility and contribute to the formation of thick siliceous gels, opaline silica or magadiite that ultimately form chert after diagenesis.…”

Section: Discussionmentioning

confidence: 99%

The role of hydrothermal fluids in sedimentation in saline alkaline lakes: Evidence from Nasikie Engida, Kenya Rift Valley

et al. 2020

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Saline alkaline lakes that precipitate sodium carbonate evaporites are most common in volcanic terrains in semi-arid environments. Processes that lead to trona precipitation are poorly understood compared to those in sulphate-dominated and chloride-dominated lake brines. Nasikie Engida (Little Magadi) in the southern Kenya Rift shows the initial stages of soda evaporite formation. This small shallow (<2 m deep; 7 km long) lake is recharged by alkaline hot springs and seasonal runoff but unlike neighbouring Lake Magadi is perennial. This study aims to understand modern sedimentary and geochemical processes in Nasikie Engida and to assess the importance of geothermal fluids in evaporite formation. Perennial hot-spring inflow waters along the northern shoreline evaporate and become saturated with respect to nahcolite and trona, which precipitate in the southern part of the lake, up to 6 km from the hot springs. Nahcolite (NaHCO 3) forms bladed crystals that nucleate on the lake floor. Trona (Na 2 CO 3 ÁNaHCO 3 Á2H 2 O) precipitates from more concentrated brines as rafts and as bottom-nucleated shrubs of acicular crystals that coalesce laterally to form bedded trona. Many processes modify the fluid composition as it evolves. Silica is removed as gels and by early diagenetic reactions and diatoms. Sulphate is depleted by bacterial reduction. Potassium and chloride, of moderate concentration, remain conservative in the brine. Clastic sedimentation is relatively minor because of the predominant hydrothermal inflow. Nahcolite precipitates when and where pCO 2 is high, notably near sublacustrine spring discharge. Results from Nasikie Engida show that hot spring discharge has maintained the lake for at least 2 kyr, and that the evaporite formation is strongly influenced by local discharge of carbon dioxide. Brine evolution and evaporite deposition at Nasikie Engida help to explain conditions under which ancient sodium carbonate evaporites formed, including those in other East African rift basins, the Eocene Green River Formation (western USA), and elsewhere.

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“…Also, rich microbial populations are found embedded within the Messinian selenite of Italy, where some of the filamentous bacteria attain mineralized outer sheaths of calcite, dolomite or pyrite (Panieri et al ., 2008). A recent study of bedded chert–dolomite cycles in the Eocene Green River Formation (USA) attributes the precipitation of lacustrine chert to the decomposition of microbial organic matter (Kuma et al ., 2019). In addition, the presence of organic matter around the foliated crystallite microstructure of shells is found to be the preferred nucleation site of silicification (Elorza & Orue‐Etxebarria, 1985; Mišík, 1995; Daley & Boyd, 1996; Butts, 2014).…”

Section: Discussionmentioning

confidence: 99%

Early silicification of the Cyrenaican chert, Libya: The importance of moganite as a transitional silicon dioxide phase

et al. 2020

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The Messinian lagoonal carbonate-evaporite sequence of Cyrenaica, northeast Libya, hosts: (i) opaline nodules in gypsiferous microbial-rich mudstone; (ii) nodules replacing poikilotopic gypsum cementing bioclastic carbonates; and (iii) bedded porcelanite with large lenticular gypsum pseudomorphs intercalated with recrystallized microbial mats. Optical microscopy, scanning electron microscopy, backscattered electron imagessecondary electron images, X-ray fluorescence, X-ray diffraction and cathodoluminescence techniques were employed to elucidate on the early stages of chert diagenesis and demonstrate the role of moganite in the formation of varieties of chalcedony during silicification. The opaline nodules composed of opal-A, exhibit shrinkage cracks lined by isopachous fibrous quartzine underlain by a thin birefringent zone. This suggests that quartzine may develop by crystallization and conversion of opal-A through a transitional moganite. The quartzine is followed by amorphous silica gel that converts into length-fast chalcedony. By contrast, lutecite evolved by silica replacement of gypsum through a transitional moganite phase, which forms an amorphous zone in apparent optical continuity with the fibrous lutecite; as moganite advances by pseudo-crystalline terminations controlled by the gypsum cleavage. In gypsified oyster shells, intercrystalline organic matter enveloping pseudomorphed shell microstructures enabled moganite nucleation that merges syntaxially around the gypsum crystal rim. The associated lutecite occurs as radial-fibrous beekite aggregates that are consistent with early shell silicification. The bedded porcelanite consists of opal-CT groundmass undergoing recrystallization and enclosing micro-cavities lined by quartzine. The associated pseudomorphs display phases of gypsum replacement by moganite and lutecite at the outer margin, followed by dissolution and cavity filling by quartz varieties in response to fluid flushing. In all cases, organic matter and microbes played a vital role in the silicification process.

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Biogenically induced bedded chert formation in the alkaline palaeo-lake of the Green River Formation

Cited by 17 publications

References 52 publications

The Significances of Cretaceous Petrified Wood Fossils from Padangcermin, Lampung in Paleoenvironmental Perspectives

The Significances of Cretaceous Petrified Wood Fossils from Padangcermin, Lampung in Paleoenvironmental Perspectives

The role of hydrothermal fluids in sedimentation in saline alkaline lakes: Evidence from Nasikie Engida, Kenya Rift Valley

Early silicification of the Cyrenaican chert, Libya: The importance of moganite as a transitional silicon dioxide phase

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