Perspectives; Oxygen isotopes and the origin of quartz

Blatt, Harvey

doi:10.1306/212f8b34-2b24-11d7-8648000102c1865d

Cited by 80 publications

(37 citation statements)

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“…The results presented here support the view that weathering of bedrock by subaerial processes is capable of producing fine sediments together with large blocks (Nahon and Trompette, 1982;Minervin, 1984;Blatt, 1987;Konischev, 1987;Ritter and Mazzullo, 1990). As mentioned above, Hewitt (1988) also showed that substantial amounts of silty-sand (between 15% and 35%) are produced when large rock avalanches occur.…”

Section: Discussionsupporting

confidence: 85%

Contemporary sediment production and transfer in high-altitude glaciers

Owen

Derbyshire

Scott

2003

Sedimentary Geology

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The nature of fine-grained sediment production and transfer in high-altitude debris-covered glaciers was studied by examining the Rakhiot and Chungphar glaciers in the Nanga Parbat Himalaya, Northern Pakistan. Transport pathways, from the source areas to the glacier snout, were mapped and samples collected for particle size analysis and scanning electron microscopy. Positive down-glacier trends in sediment fining and increased weathering showed that debris transport in the supraglacial zone of these Himalayan glaciers is an important contributor to contemporary glacial sediment production, resulting in intense comminution that yields large volumes of fine sediment. These findings cast doubt on the traditional view that the basal traction zone of glaciers is the only major source of fine sediment production in glaciated environments, although that view may hold true for classic alpine glaciers that are at lower altitudes and, as a consequence, generally have less supraglacial debris cover. To test this hypothesis, the Glacier de Cheilon, in the Swiss Alps was also studied. This glacier did not exhibit such striking down-glacier trends in the particle size characteristics measured. It is thus suggested that a thick debriscover may be an important source of fine-grained sediments on glaciers that occur in high-altitude environments. D

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Section: Discussionsupporting

confidence: 85%

Contemporary sediment production and transfer in high-altitude glaciers

Owen

Derbyshire

Scott

2003

Sedimentary Geology

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“…Silt is abundant in the sedimentary rock record. Indeed, Blatt (1987) estimates that fully half of the detrital quartz in the world's sedimentary rocks consists of siltsized particles. In the case of Peoria Loess in the Great Plains of Nebraska, our data and those of Aleinikoff et al (2008) indicate that sedimentary rock is probably the most important source of silt-sized particles.…”

Section: "Glacial" Loess and "Desert" Loessmentioning

confidence: 99%

Origin and paleoclimatic significance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry

Muhs

Bettis

Aleinikoff

et al. 2008

Geological Society of America Bulletin

127

104

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Rachel, "Origin and paleoclimatic signifi cance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry" (2008 The spatial variability of particle size abundances in Peoria Loess shows a northwest-to-southeast fi ning in Nebraska, consistent with maps of previous workers that show a northwest-to-southeast thinning of loess. These observations indicate that paleowinds that deposited the loess were from the west or northwest and that the source or sources of Peoria Loess lay to the west or northwest.New mineralogical and geochemical data indicate that the most important sources of loess were likely Tertiary siltstones of the White River and Arikaree Groups, silt facies of Pliocene eolian sediments, and small contributions from Pierre Shale. It is likely that fi ne-grained silts were transported episodically through the Nebraska Sand Hills from

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“…By analogy, clusters of euhedral quartz crystals may also reflect growth into pores. The presence of phyllosilicates in detrital-rich sediments (e.g., Zones I, IV, and V) can physically restrict the growth of euhedral quartz (Blatt 1987), thereby governing both crystal size and shape.…”

Section: Discussion Of Chert Petrographymentioning

confidence: 99%

Sedimentology and petrography of early diagenetic chert and dolomite in the Late Cretaceous‐early Tertiary Amuri Limestone Group, eastern Marlborough, New Zealand

Lawrence

1993

New Zealand Journal of Geology and Geophysics

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The dominantly micritic Amuri Limestone Group of eastern Marlborough, New Zealand, consists of six regionally extensive units: the Mead Hill Formation, Teredo Limestone Formation, Lower Limestone Formation, Middle Limestone Formation, and the Lower and Upper Marl Formations, which were deposited in a northwest-trending trough. Six separate diagenetic zones (I-VI) are recognised, based on visually estimated proportions of chert, dolomite, or limestone. Zones I-V occur in the Mead Hill to Lower Limestone Formations, and Zone VI occurs in the Middle Limestone Formation. There is no chert or dolomite in the two Marl formations. The bulk of the chert and dolomite occurs in the basin centre (mainly in the Mead Hill Formation) where the limestone is thickest, but decreases in abundance stratigraphically upwards and towards the basin margins. Zone I consists almost entirely of chert which is either detrital rich or detrital poor. Zones II and IV consist of chert and dolomite in approximately equal proportions. Zones III and VI contain varying proportions of chert and limestone. Zone V is a thin, chertified, fine sandstone-mudstone of limited extent. Sulphide nodules, usually <10 mm in diameter, are common in all zones. Chert usually forms discontinuous nodular beds or nodules. Some elongated chert nodules which may be in excess of 2 m (chert bands) are found near the top of the chert sequence. Dolomite occurs as <1 mm diameter rhombohedra in discontinuous chert-cemented beds and lenses. The common pinch and swell morphology displayed throughout most zones results from differential compaction of relatively chert-free limestone, or dolomite, around chert nodules. Stylolites are generally absent, but where present they are deflected around chert nodules, indicating chert formation prior to stylolitisation.In thin section, Zone II dolomites contain inclusions arranged in cloudy-centre clear-rim patterns. Zone IV dolomite has inclusions arranged in diagonal planes. Both dolomite types are associated with abundant disseminated pyrite. All cherts consist of microcrystalline or cryptocrystalline quartz or chalcedony, with common disseminated pyrite. Petrographic evidence and δ 18 O data indicate that the Received 20 February 1992; accepted 19 November 1992 dolomite formed at temperatures <60°C, probably in the upper sediment column. The presence of pyrite suggests that dolomite formed in association with sulphate reduction. The δ 18 O composition of the chert is very similar to that of the dolomite, implying that chert formation may have occurred at similar depths and times in the sediment as the dolomite. The association of pyrite with chert suggests that sulphate reduction may also have promoted silica nucleation. Therefore, the sedimentological and petrographic evidence is consistent with the early nucleation of both chert and dolomite. G92009

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Perspectives; Oxygen isotopes and the origin of quartz

Cited by 80 publications

References 0 publications

Contemporary sediment production and transfer in high-altitude glaciers

Contemporary sediment production and transfer in high-altitude glaciers

Origin and paleoclimatic significance of late Quaternary loess in Nebraska: Evidence from stratigraphy, chronology, sedimentology, and geochemistry

Sedimentology and petrography of early diagenetic chert and dolomite in the Late Cretaceous‐early Tertiary Amuri Limestone Group, eastern Marlborough, New Zealand

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