The central Australian groundwater discharge zone: Evolution of associated calcrete and gypcrete deposits

Jacobson, G.; Arakel, A. V.; Yijian, Chen

doi:10.1080/08120098808729469

Cited by 77 publications

(54 citation statements)

References 9 publications

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“…1 lb) suggest a similar environment. The three calcretes tend to have lower delta lsO values than those reported for the arid climate groundwater calcretes of Central Australia (Jacobson et al 1988), which would reflect a less arid climate. More constrained values for the Saint-Elz6ar calcrete may reflect its higher maturity which, as mentioned above, is also suggested by its structure and composition.…”

Section: Stable Isotopesmentioning

confidence: 45%

“…Quaternary groundwater calcretes are abundantly recorded in Australia where they are laterally associated with gypsum-rich playa-sequences (Mann and Horwitz 1979;Arakel and McConchie 1982;Jacobson et al 1988;Arakel et al 1989). If evaporite patches remain, they would most probably be under Chaleur Bay or under the thick Bonaventure Formation sequence that extends south-southwest of the Cap Blanc Fault (Fig.…”

Section: Discussion Sedimentologymentioning

confidence: 99%

“…In modem records, such massive groundwater calcretization appears to be systematically associated with the presence of salt (Mann and Horwitz 1979;Arakel and McConchie 1982;Jacobson et al 1988;Arakel et al 1989). Is mixing with saline water required for the development of such thick non-pedogenic 'hardpans'?…”

Section: Discussion Sedimentologymentioning

confidence: 99%

“…It is therefore not possible to determine whether the fan was connected to a lake, a sea or an alluvial plain. However, a fan-delta model would partly explain some of the non-arid features of the La Coulee Formation and perhaps even the extensive calcretization that has affected it: since groundwater calcretes tend to develop in drainage systems where the water table is very close to the surface, their formation usually occurs in proximity to a body of water, very often close to salt lakes and playas, in the groundwater discharge zone where fresh and saline waters mix (Mann and Horwitz 1979;Arakel and McConchie 1982;Jacobson et al 1988;Arakel et al 1989).…”

Section: Discussion Sedimentologymentioning

confidence: 99%

“…Local silicification is typical of groundwater calcretes (Arakel and McConchie 1982;Jacobson et al 1988;Arakel et al 1989;Wright and Tucker 1991) and is most probably responsible for the preservation of the limestone clasts. Figure 3e indicates how siliceous calcrete clasts observed throughout the calcrete are formed directly from the host sediment by mineral replacement.…”

Section: Groundwater Calcrete Facies (0-11 Metres)mentioning

confidence: 99%

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The La Coulée Formation, a new post-Acadian continental clastic unit bearing groundwater calcretes, Gaspé Peninsula, Quebec

Jutras

Prichonnet

Bitter

1999

atgeol

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A 1 km2 erosional remnant of the La Coulee Formation, a previously unrecognized stratigraphic unit, has been studied in the Percd area of the Gaspe Peninsula. It unconformably overlies folded Cambrian to Devonian rocks and is unconformably overlain by the mid-Carboniferous Bonaventure Formation. The erosional remnant includes the lowest 60 m of this newly identified formation of unknown thickness. Original sedimentary facies are limited to 50 m of breccia debris flows passing stratigraphically upward into 10 m of conglomeratic debris flows. Groundwater calcrete formation has partially or completely transformed the lowest 30 m of the sequence. The depositional environment is interpreted as being related to a proximal continental alluvial fan. The nearby presence of a saline body of water is inferred to account for thick and massive groundwater calcrete formation and water-saturated debris flows in a relatively arid climatic context. Most of the formation was eroded prior to deposition of the Bonaventure Formation. However, the basal groundwater calcretes were more widely preserved. They underlie the Bonaventure Formation in most of the Percd area and in the Saint-Elzear area, close to a hundred kilometres to the southwest. Post-sedimentary faulting has affected both the La Coulde and Bonaventure formations.La Formation de La Coulee, une unite stratigraphique nouvellement repertoride, a etd etudiee a l'interieur d'une masse residuelle de lkm2 dans la region de Percd en Gaspdsie. La sequence recouvre en discordance des roches plissees du Ddvonien Inferieur et elle est recouverte en discordance par la Formation de Bonaventure qui est attribude au Carbonifdre moyen. La masse residuelle inclue les 60 premiers mdtres de cette formation nouvellement identifide et d'une dpaisseur inconnue. Les facids sedimentaires originels sont limitds k cinquante metres de coulees de ddbris brdchiques, passant a une dizaine de mdtres de couldes de ddbris conglomdratiques. La formation d'une calcrete phrdatique affecte les premiers 30 mdtres de la sdquence, lesquels sont en partie ou compldtement transformds. L'environnement sddimentaire est interprdtd comme dtant lid k un c6ne de ddjection continental dans sa partie proximale, mais la prdsence non-lointaine d'un plan d'eau salde est suggdrde pour expliquer la formation de calcretes phrdatiques epaisses et massives, ainsi que la saturation en eau des couldes de ddbris dans un contexte climatique relativement aride. La formation a presqu'entidrement dtd drodde avant que ne survienne la sddimentation de la Formation de Bonaventure. Toutefois, la base de calcrete a dtd plus largement prdservde, ce qui fait qu'on la retrouve sous la Formation de Bonaventure presque partout dans la rdgion de Percd ainsi que dans la rdgion de Saint-Elzdar, k presqu'une centaine de kilomdtres au sud-ouest. Des failles post-sedimentaires ont affectd a la fois la Formation de La Coulde et la Formation de Bonaventure.

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Section: Stable Isotopesmentioning

confidence: 45%