Clay mineralogy and chemistry as indicators of hemipelagic sediment dispersal south of the Aleutian arc

Hathon, Eric G.; Underwood, Michael B.

doi:10.1016/0025-3227(91)90024-x

Cited by 21 publications

(20 citation statements)

References 46 publications

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“…Given the previous findings of Hathon and Underwood (1991), the best chemical indicator of illite and/or detrital muscovite content in a mixture of clay-sized minerals should be K 2 O. Nevertheless, our regression analyses failed to produce statistically significant correlation coefficients (Fig.…”

Section: Clay Compositionmentioning

confidence: 62%

“…Relative proportions of smectite, illite, and kaolinite should be the most straightforward variables to influence the geochemistry of claysized constituents, and Hathon and Underwood (1991) showed that the best chemical indicators of clay mineralogy are Al 2 O 3 , SiO 2 , and K 2 O. To test these contentions, we constructed regression plots of major-oxide percentages and major-oxide ratios (relative to alumina) vs. the estimated abundance of each clay mineral within the <1-µm size fraction.…”

Section: Clay Compositionmentioning

confidence: 99%

“…The SEM/EDS study of Hathon and Underwood (1991) did not include analyses of kaolinite, but its chemical signature should be easy to recognize. Relative percentages of kaolinite from Site 948 correlate effectively with weight percentages of all major oxides except TiO 2 and CaO (Fig.…”

Section: Clay Compositionmentioning

confidence: 99%

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Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

Underwood¹,

Deng²

1997

Proceedings of the Ocean Drilling Program, 156 Scientific Results

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Fine-grained sediments recovered during Leg 156 of the Ocean Drilling Program contain assemblages of clay minerals that change considerably with depth. Key structural and stratigraphic features within the toe of the northern Barbados accretionary prism include the basal décollement and a sharp boundary between lithologic Units II and III; this lithologic boundary occurs within the décollement zone. We analyzed three size fractions (4−8 µm, 1−4 µm, and <1 µm) by X-ray diffraction and obtained chemical data from the <1-µm size fractions by scanning electron microscopy coupled with energy dispersive spectroscopy. Relative proportions of expandable clay minerals increase significantly, but erratically, near the top of the décollement zone. Proportions of discrete smectite and smectite-rich illite/smectite (I/S) mixed-layer clays decrease steadily down the décolle-ment zone. The base of the décollement zone is characterized by unusually high concentrations of illite. These changes in clay mineralogy influence the shear strength of claystones at the deformation front and help control the position of the décollement.Relative abundances of illite within all lithofacies units increase in coarser size fractions, and this trend is consistent with a detrital source. Kaolinite does not display any systematic partitioning within Unit II, but its proportions increase in the finer size fractions within Unit III. The smectite content of Unit II increases with decreasing grain size; Unit III shows the opposite trend between particle size and % smectite. Bentonite-like samples probably originated through in situ alteration of disseminated volcanic ash, but we believe that the pyroclastic material was mixed into a background sediment that already contained abundant detrital smectite. Illitic mixed-layer clays within the underthrust domain (Unit III) also appear to be detrital in origin. Correlations among both % smectite and % kaolinite and most major-element oxides are statistically significant, but correlations for illite are not. Expandable clays vary considerably in their chemical make-up; the most common type appears to be a Mg-poor, K-rich, Fe-Al-beidellite. We rely upon actualistic provenance connections for late Quaternary clays to guide our interpretations of Miocene and Oligocene sediment dispersal. If these analogues are valid, then the proto-Orinoco and protoAmazon Rivers were the most important detrital sources for the older hemipelagic and turbidite deposits of Barbados Ridge.

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Section: Clay Compositionmentioning

confidence: 62%

Section: Clay Compositionmentioning

confidence: 99%

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Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

Underwood¹,

Deng²

1997

Proceedings of the Ocean Drilling Program, 156 Scientific Results

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“…On the other hand, the background fallout of suspended sediment does not always mimic the sediment provenance of interlayered turbidites (e.g., compare Underwood, 1986Underwood, , 1991and Hathon and Underwood, 1991). Repeated episodes of mud resuspension and mineral homogenization are common within the bottom nepheloid layer in response to bioturbation, thermohaline bottom currents, and turbidity currents.…”

Section: Discussionmentioning

confidence: 99%

“…Many of the published data sets for marine sediments are based on the Biscaye weighting factors (e.g., Griffin et al, 1968;Hein et al, 1976;Scholl et al, 1977;Naidu and Mowatt, 1983;Tribble, 1990;Hathon and Underwood, 1991), so we made the same types of calculations of relative mineral abundance to facilitate easy comparison with other results. As a test of accuracy, we also analyzed experimental mixtures of known weight percentages using various combinations of smectite, illite, and chlorite obtained from the Clay Mineral Society repository at the University of Missouri.…”

Section: Error Analysismentioning

confidence: 99%

Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

Underwood¹,

Orr²,

Pickering³

et al. 1993

Proceedings of the Ocean Drilling Program

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Drill core recovered at Ocean Drilling Program Site 808 (Leg 131) proves that the wedge of trench sediment within the central region of the Nankai Trough comprises approximately 600 m of hemipelagic mud, sandy turbidites, and silty turbidites. The stratigraphic succession thickens and coarsens upward, with hemipelagic muds and volcanic-ash layers of the Shikoku Basin overlain by silty and sandy trench-wedge deposits. Past investigations of clay mineralogy and sand petrography within this region have led to the hypothesis that most of the detritus in the Nankai Trough was derived from the Izu-Honshu collision zone and transported southwestward via axial turbidity currents. Shipboard analyses of paleocurrent indicators, on the other hand, show that most of the ripple cross-laminae within silty turbidites of the outer marginal trench-wedge facies are inclined to the north and northwest; thus, many of the turbidity currents reflected off the seaward slope of the trench rather than moving straight down the trench axis. Shore-based analyses of detrital clay minerals demonstrate that the hemipelagic muds and matrix materials within sandy and silty turbidites are all enriched in illite; chlorite is the second-most abundant clay mineral, followed by smectite. In general, the relative mineral percentages change relatively little as a function of depth, and the hemipelagic clay-mineral population is virtually identical to the turbidite-matrix population.Comparisons between different size fractions (<2 µm and 2-6 µm) show modest amounts of mineral partitioning, with chlorite content increasing in the coarser fraction and smectite increasing in the finer fraction. Values of illite crystallinity index are consistent with conditions of advanced anchimetamoΦhism and epimetamoΦhism within the source region. Of the three mica poly types detected, the 2Mj variety dominates over the IM and IMd polytypes; these data are consistent with values of illite crystallinity. Measurements of mica b o lattice spacing show that the detrital illite particles were eroded from a zone of intermediate-pressure metamoΦhism. Collectively, these data provide an excellent match with the lithologic and metamoΦhic character of the Izu-Honshu collision zone. Data from Leg 131, therefore, confirm the earlier inteΦ r etations of detrital provenance. The regional pattern of sediment dispersal is dominated by a combination of southwest-directed axial turbidity currents, radial expansion of the axial flows, oblique movement of suspended clouds onto and beyond the seaward slope of the Nankai Trough, and flow reflection back toward the trench axis.

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Modern modes of provenance and dispersal of terrigenous sediments in the North Pacific and Bering Sea: implications and perspectives for palaeoenvironmental reconstructions

et al. 2016

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During expedition 202 aboard the RV Sonne in 2009, 39 seafloor surface sediment sites were sampled over a wide sector of the North Pacific and adjoining Bering Sea. The data served to infer land-ocean linkages of terrigenous sediment supply in terms of major sources and modes of sediment transport within an over-regional context. This is based on an integrated approach dealing with grain-size analysis, bulk mineralogy and clay mineralogy in combination with statistical data evaluation (end-member modelling of grainsize data, fuzzy cluster analysis of mineralogical data). The findings on clay mineralogy served to update those of earlier work extracted from the literature. Today, two processes of terrigenous sediment supply prevail in the study area: fardistance aeolian sediment supply to the pelagic North Pacific, and hemipelagic sediment dispersal from nearby land sources via ocean currents along the continental margins and island arcs. Aeolian particles show the finest grain sizes (clay and fine silt), whereas hemipelagic sediments have high abundances of coarse silt. Exposed sites on seamounts and the continental slope are partly swept by strong currents, leading to residual enrichment of fine sand. Four sediment sources can be distinguished on the basis of distinct index minerals revealed by statistical data analysis: dust plumes from central Asia (quartz, illite), altered materials from the volcanic regions of Kamchatka and the Aleutian Arc (smectite), detritus from the Alaskan Cordillera (chlorite, hornblende), and fluvial detritus from far-eastern Siberia and the Alaska mainland (quartz, feldspar, illite). These findings confirm those of former studies but considerably expand the geographic range of this suite of proxies as far south as 39°N in the open North Pacific. The present integrated methodological approach proved useful in identifying the major modern processes of terrigenous sediment supply to the study region. This aspect deserves attention in the selection of sediment core sites for future palaeoenvironmental reconstructions related to aeolian and glacial dynamics, as well as the recognition of palaeoocean circulation patterns in general.

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Clay mineralogy and chemistry as indicators of hemipelagic sediment dispersal south of the Aleutian arc

Cited by 21 publications

References 46 publications

Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

Clay mineralogy and clay geochemistry in the vicinity of the décollement zone, northern Barbados Ridge

Provenance and Dispersal Patterns of Sediments in the Turbidite Wedge of Nankai Trough

Modern modes of provenance and dispersal of terrigenous sediments in the North Pacific and Bering Sea: implications and perspectives for palaeoenvironmental reconstructions

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