Significance of trace elements in syntaxial quartz cement, Haushi Group sandstones, Sultanate of Oman

Lehmann, Katja; Pettke, Thomas; Ramseyer, Karl

doi:10.1016/j.chemgeo.2010.10.013

Cited by 39 publications

(19 citation statements)

References 34 publications

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“…The trace element compositions of quartz cements in the Finefrau and Solling sandstones are in general similar to those reported for other authigenic and hydrothermal quartz formed at low temperatures (Demars et al ., ; Rusk et al ., ; Jourdan et al ., ; Götte et al ., ; Lehmann et al ., ). In detail, the trace elements in quartz cements in the two sandstones vary in three aspects: (i) the Al‐content; (ii) the ratio of Li + ‐compensated and H + ‐compensated Al‐defects; and (iii) the Ge‐content.…”

Section: Discussionmentioning

confidence: 97%

“…Hydrochemical modelling results from Lehmann et al . () indicate that a high pH (i.e. low partial pressure of CO 2 ), a change from a quartz‐kaolinite to a quartz‐illite assemblage and an increase in temperature are favourable conditions for an increased Al‐concentration in solution.…”

Section: Discussionmentioning

confidence: 99%

“…Diagenesis of Coal Measure deposits adjacent to the Finefrau Sandstone probably results in high partial pressures of CO 2 during the formation of the first and second quartz cement (Füchtbauer, ). These conditions are not generally favourable for high Al‐concentrations in authigenic quartz (Lehmann et al ., ), because the solubility of clay minerals has a minimum under slightly acid conditions. It is suggested that the latest quartz cement (Qz 3) formed when the discharge of CO 2 from the coal measures decreased.…”

Section: Discussionmentioning

confidence: 99%

“…Aluminium, Li, Na and H are the most important trace elements incorporated in authigenic and hydrothermal quartz grown at low temperatures (< 300° C; Bambauer, ; Jourdan et al ., ; Lehmann et al ., ; Götte et al ., ). Detectable amounts of B, P and Ge are commonly also present.…”

Section: Introductionmentioning

confidence: 99%

“…It has been suggested that the Al‐content is related to diagenesis of feldspars (Kraishan et al ., ; Weber & Ricken, ), while Lehmann et al . () proposed Ge as a proxy element for the silica source and linked the Al‐content to the evolution of the pore‐water. The most important source of Li is clay minerals (Williams & Hervig, ) and enrichment in this element may point to clay mineral transformations.…”

Section: Introductionmentioning

confidence: 99%

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Implications of trace element composition of syntaxial quartz cements for the geochemical conditions during quartz precipitation in sandstones

Götte

Ramseyer²,

Pettke³

et al. 2013

Sedimentology

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A petrographic investigation revealed polyphase quartz cementation in the Finefrau Sandstone (Upper Carboniferous, Western Germany) and the Solling Sandstone (Lower Triassic, Central Germany). Three different cements could be distinguished in each sandstone based on their cathodoluminescence and trace element composition. The first quartz generation is suggested to have been formed during eogenesis due to dissolution and replacement of feldspar. The mesogenetic paragenesis comprises two generations of quartz and illite, which are accompanied by albite in the Solling Sandstone. Sharp luminescence zoning in quartz overgrowths points to distinct episodes of cementation in both sandstones. Significant amounts of Al, Li and H and traces of Ge and B have been detected in the quartz overgrowths. The Al-content of the quartz cements in the Finefrau Sandstones exceeds that in the quartz cements in the Solling Sandstone by a factor of five. It is suggested that this compositional variation reflects the conditions in the pore-water, such as temperature and pH. The Al-concentration is generally correlated to the Li-content with the exception of the latest quartz generation in the Finefrau Sandstones which is also most enriched in trace elements. The ratio of Li/Al varies between 0Á11 and 0Á25 in the two sandstones. The Li/H-ratio, which ranges from 0Á12 to 0Á3, is controlled by the activity ratio of Li and H in the pore fluid. Clay minerals are the most important source for Li and high salinities favour the mobilization of Li during diagenesis. Thus, a relatively low salinity and low pH are responsible for the low Li/H-ratio in the Finefrau Sandstone, while high salinity and neutral to alkaline pH results in a high Li/H-ratio for the Solling Sandstone. The Gecontents are generally near the average of detrital quartz and indicate that pressure dissolution is a major source for quartz cementation. Different chemical compositions of distinct quartz generations indicate changes in the physico-chemical conditions and point to mobilization of silica from different sources (for example, pressure solution and clay mineral transformations).

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