Classification of poorly-sorted sedimentary rocks

Moncrieff, A.C.M.

doi:10.1016/0037-0738(89)90015-8

Cited by 127 publications

(81 citation statements)

References 5 publications

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“…Sediment classification diagram (Shepard, 1954 Figure F18. Modified classification scheme of poorly sorted sediments with a gravel component to facilitate the characterization of diamicts, conglomerates, and breccias, after Moncrieff (1989 1%-5% 5%-30% 30%-80% >80% Figure F19. Graphic overview of syringe sampling scheme used when taking multiple samples from each microbiology core.…”

Section: Methodsmentioning

confidence: 99%

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Methods

Andrén¹,

Jørgensen²,

Cotterill³

et al. 2015

Proceedings of the IODP

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This chapter documents the primary operational, curatorial, and analytical procedures and methods employed during the offshore and onshore phases of Integrated Ocean Drilling Program (IODP) Expedition 347. This information concerns only shipboard and Onshore Science Party (OSP) methodologies and data as described in the site chapters. Methods for postexpedition research conducted on Expedition 347 samples and data will be described in individual scientific contributions published after the OSP. Detailed drilling and engineering operations are described in "Operations" within each site chapter and "Operational strategy" in the "Expedition 347 summary" chapter (Andrén et al., 2015). The information in this chapter will enable future identification of data and samples for further scientific investigation by interested parties. Site locationsAll Expedition 347 sites (Fig. F1) were positioned using GPS coordinates supplied by the proponents and based on previous site surveys. As a number of holes were proposed at each site for different uses (e.g., paleoenvironment and microbiology), a central hole position was taken from the proponent-supplied coordinates (Hole A), and then additional positions were calculated radiating out from this position at 20 m intervals, with Holes B and C on either side of Hole A, running along the site survey seismic lines, and Holes D and E perpendicular to this orientation, again on either side of Hole A (Fig. F2). The spacing interval of 20 m between holes was chosen to limit drilling disturbance between holes while maintaining a close enough proximity to correlate between them, enabling the formation of a composite recovery and lithologic splice.Selected positions were relayed to the Hydrographic Surveyor from Geocean, and the Greatship Manisha was settled into position using a dynamic positioning (DP) system. To maintain station accurately within the required tolerance of <1 m for shallowwater sites, the DP system ran for 30-40 min at each location to build a reliable DP model, after which permission was granted to commence operations. Geocean supplied two transponder systems that were used during coring operations as backup for the DP system should there be a failure in the differential GPS (DGPS) signal because of satellite angles, particularly in the river estuary Methods 1

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Section: Methodsmentioning

confidence: 99%

“…The term "mud" describes a subequal mixture of silt and clay. For sediments with a gravel component, a modified version of the classification scheme of Moncrieff (1989) was used ( Fig. F18).…”

Section: Sediment Classificationmentioning

confidence: 99%

Methods

Andrén¹,

Jørgensen²,

Cotterill³

et al. 2015

Proceedings of the IODP

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“…Although diamictites have been recognized for over 50 years as important facies in depositional systems that are not related to glacial sedimentation, the distinction between glacial and non-glacial diamictites is still neglected. Some good reviews on the theme and distinction criteria between glacial and non-glacial diamictites can be found in the works of Schermerhorn (1974), Boulton & Deynoux (1981), Dreimanis & Schucluter (1985), Moncrieff (1989), Eyles (1993), Miller (1996 and Uhlein et al (2004). The intercalation of thin layers (decimeters to meters) of diamictites with sandstones and pelites, deposited in submarine conditions, and the association with turbidites, do not allow defining these rocks as tillites (glacio-terrestrial rock).…”

Section: Facies Sedimentary Environments and Depositional Systems Ofmentioning

confidence: 99%

Depositional systems and stratigraphic review proposal of the Rio Preto Fold Belt, northwestern Bahia/southern Piauí

Caxito

Uhlein

Sanglard

et al. 2012

RBG

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The Rio Preto Fold Belt borders the northwestern São Francisco Craton margin, in northwestern Bahia state. The precursor basin to the fold belt is represented by the km-thick Canabravinha Formation, composed of lithic quartzite, phyllite, sandy-pelitic metarhythmite, metadiamictite, and locally metamarl. Its deposition occurred on a submarine slope-apron dominated by gravitational flows like mud flows and turbidity currents in an east-west trending asymmetric rift or hemi-graben, bounded by a faulted border on the south and a possible flexural border towards the north. The sediment supply came mostly downslope from the São Francisco Craton to the south. In the northern portion of the fold belt, the Formosa Formation probably represents part of the Paleoproterozoic basement, composed of garnetmica schist, quartzite, iron-manganese metachert, greenschist, and locally orto-amphibolite intercalations. The Formosa Formation was probably deposited in an arc-related basin 1.9 Ga ago. A stratigraphic review proposal is based on two points: 1) Removal of the Canabravinha Formation from the base of the Bambuí Group and its positioning as a chronostratigraphic equivalent to the diamictite-bearing units on the other fold belts that surround the São Francisco Craton; 2) Replacement of the term Rio Preto Group for the term Formosa Formation, once that its rocks can't be individualized into formations. The pre-orogenic sedimentation on the Rio Preto Fold Belt occurred between 850 and 600 Ma ago. During the Brasiliano Orogeny (600 -540 Ma), the sedimentary basin was metamorphosed at the greenschist facies and inverted, assuming a kilometric doubly-vergent fan structure.Keywords: Rio Preto Fold Belt; São Francisco Craton; Brasiliano Orogeny. ResumoSistemas deposicionais e proposta de revisão estratigráfica da Faixa Rio Preto, Noroeste da Bahia/Sul do Piauí. A Faixa Rio Preto bordeja a margem noroeste do Cráton do São Francisco, no noroeste do estado da Bahia. A bacia precursora da faixa dobrada é representada pela Formação Canabravinha, de espessura quilométrica, composta por quartzito lítico, filito, metaritmito areno-pelítico, metadiamictito, e, localmente, metamarga. Sua deposição ocorreu em um ambiente de talude submarino dominado por fluxos gravitacionais tais como fluxos de lama e correntes de turbidez, em um rift ou hemi-graben assimétrico de direção leste-oeste, com uma borda falhada a sul e uma possível borda flexural a norte. O aporte sedimentar foi predominantemente talude abaixo, do Cráton do São Francisco a sul, para norte. Na porção norte da faixa dobrada, a Formação Formosa provavelmente representa parte do embasamento Paleoproterozoico, composta por granada-mica xisto, quartzito, metachert ferro-manganesífero, xisto verde, e localmente, intercalações de orto-anfibolito. A Formação Formosa foi provavelmente depositada em uma bacia relacionada a arco magmático 1,9 Ga atrás. Uma proposta de revisão estratigráfica é baseada em dois pontos: 1) Retirada da Formação Canabravinha da base do Grupo Bambuí e seu pos...

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“…Most diamictites are stratified, but massive varieties also occur. Clast content ranges from 2% to 30% (Moncrieff, 1989), and matrix is typically a mixture of sand and mud. Stratified variants preserve crude planar stratification and soft-sediment deformation structures.…”

Section: Glacigenic Facies Associationmentioning

confidence: 99%