High-resolution late Paleozoic cyclostratigraphy and tectonic evolution of the Keeler Basin, California, southwest Laurentia

Cyclic strata exposed in the Inyo Mountains of eastern California contain a continuous 6 m.y. record of deep marine deposition that spans the Pennsylvanian−Permian boundary. To better understand the geologic evolution of southwest Laurentia and the role of glacially driven eustasy in upper Paleozoic stratigraphy, we measured two detailed ∼600 m composite stratigraphic sections of the Keeler Canyon Formation and collected a handheld spectral gamma ray log. Post-depositional deformation complicates field relationships, but 1:5000 scale mapping of faults and folds permits assembly of two continuous sections. Measured strata alternate at the 5−20 m scale between intervals of fine-grained laminated marlstone and intervals of mixed carbonate and siliciclastic turbidites and debrites. Based on facies characteristics and a prominent marker horizon, we reassign the Pennsylvanian-Permian age upper Salt Tram unit of the upper Keeler Canyon Formation to a new Estelle Member. We estimate sediment accumulation rates within the Keeler Canyon Formation using published conodont biostratigraphy and correlative U-Pb geochronology from Eastern Europe combined with spectral analysis and timescale optimization using the Astrochron R package. Evolutive harmonic analysis of gamma ray-derived element concentrations reveals prominent bundled periodicities that are consistent with both long and short eccentricity cycles. Average sediment accumulation rates calculated using the time scale optimization function of Astrochron suggest a gradual increase from 40−60 m/m.y. to ∼120 m/m.y. during the late Pennsylvanian and then a minima of ∼50 m/m.y. near the Pennsylvanian−Permian boundary, which is followed by an increase to ∼175 m/m.y. into the Early Permian. This trend in sediment accumulation rates and subsequent Permian contractile deformation are compatible with flexural subsidence in a SW-migrating foreland basin related to the southern part of the late Antler orogenic system.

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Vertical and lateral flux on the continental slope off Pakistan: correlation of sediment core and trap results

Biogeosciences ◽

10.5194/bg-11-3107-2014 ◽

2014 ◽

Vol 11 (12) ◽

pp. 3107-3120 ◽

Cited By ~ 4

Author(s):

H. Schulz ◽

U. von Rad

Keyword(s):

Continental Slope ◽

Sediment Cores ◽

Sediment Accumulation ◽

Lower Boundary ◽

Distribution Patterns ◽

Sediment Traps ◽

Accumulation Rates ◽

Fine Grained ◽

Minimum Zone ◽

The Individual

Abstract. Due to the lack of bioturbation, the varve-laminated muds from the oxygen minimum zone (OMZ) off Pakistan provide a unique opportunity to precisely determine the vertical and lateral sediment fluxes in the nearshore part of the northeastern Arabian Sea. West of Karachi (Hab area), the results of two sediment trap stations (EPT and WPT) were correlated with 16 short sediment cores on a depth transect crossing the OMZ. The top of a distinct, either reddish- or light-gray silt layer, 210Pb-dated as AD 1905 ± 10, was used as an isochronous stratigraphic marker bed to calculate sediment accumulation rates. In one core, the red and gray layer were separated by a few (5–10) thin laminae. According to our varve model, this contributes < 10 years to the dating uncertainty, assuming that the different layers are almost synchronous. We directly compared the accumulation rates with the flux rates from the sediment traps that collected the settling material within the water column above. All traps on the steep Makran continental slope show exceptionally high, pulsed winter fluxes of up to 5000 mg m−2 d−1. Based on core results, the flux at the seafloor amounts to 4000 mg m−2 d−1 and agrees remarkably well with the bulk winter flux of material, as well as with the flux of the individual bulk components of organic carbon, calcium carbonate and opal. However, due to the extreme mass of remobilized matter, the high winter flux events exceeded the capacity of the shallow traps. Based on our comparisons, we argue that high-flux events must occur regularly during winter within the upper OMZ off Pakistan to explain the high accumulations rates. These show distribution patterns that are a negative function of water depth and distance from the shelf. Some of the sediment fractions show marked shifts in accumulation rates near the lower boundary of the OMZ. For instance, the flux of benthic foraminifera is lowered but stable below ~1200–1300 m. However, flux and sedimentation in the upper eastern Makran area are dominated by the large amount of laterally advected fine-grained material and by the pulsed nature of the resuspension events at the upper margin during winter.

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The use of magnetic susceptibility and trace element geochemistry for the correlation of fine-grained siliciclastic sequences: a Late Llandovery example from northwest England

Geological Magazine ◽

10.1017/s0016756899002587 ◽

1999 ◽

Vol 136 (4) ◽

pp. 423-436 ◽

Cited By ~ 4

Author(s):

L. T. P. ENGLISH

Keyword(s):

Magnetic Susceptibility ◽

Bottom Water ◽

Sediment Accumulation ◽

Clay Mineralogy ◽

Manganese Carbonate ◽

Trace Element Geochemistry ◽

Accumulation Rates ◽

Element Geochemistry ◽

Fine Grained ◽

Water Oxygen

High-resolution lithological and magnetic susceptibility logs were made of two sections of the Upper Llandovery Browgill Formation in northwest England: Stockdale Beck, the type section of the Browgill Formation, and Spengill. The Browgill Formation is composed of fine-grained deep marine siliciclastics, which can be divided broadly into two facies: a homogeneous grey mudstone, deposited under oxygenated bottom-water conditions, and subordinate beds of laminated, graptolite-bearing black mudstone deposited under low bottom-water oxygen levels. The latter facies is often partially or fully diagenetically altered to chlorite nodules, occasionally with manganese carbonate nucleii. Magnetic susceptibility logs are shown to reflect variations in the illite–chlorite ratio of the clay mineralogy. Chlorite is a paramagnetic mineral, so the bands of chlorite nodules produce magnetic susceptibility highs. Correlation demonstrates that diagenetically altered beds of laminated black mudstone are continuous between the two sections, now situated 32 km apart. This lateral continuity would favour pelagic fallout in preference to gravity flow as a depositional model for both facies. A correlated sequence within the turriculatus Biozone is 3.8 times thicker at Spengill than at Stockdale Beck, probably reflecting variations in sediment accumulation rates. Correlation also identifies significant non-sequences in both sections: at least 47% of the turriculatus Biozone (including maximus Sub-biozone) is missing at Stockdale Beck and at least 77% of the crispus Biozone is missing at Spengill. The identification of non-sequences may be of value for refining graptolite biostratigraphy.

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Tectonic control on sedimentary facies pattern and sediment accumulation rates in the Miocene foreland basin of the southern Alborz mountains, northern Iran

Tectonics ◽

10.1029/2008tc002278 ◽

2008 ◽

Vol 27 (6) ◽

pp. n/a-n/a ◽

Cited By ~ 66

Author(s):

Paolo Ballato ◽

Norbert R. Nowaczyk ◽

Angela Landgraf ◽

Manfred R. Strecker ◽

Anke Friedrich ◽

...

Keyword(s):

Sediment Accumulation ◽

Foreland Basin ◽

Sedimentary Facies ◽

Accumulation Rates ◽

Northern Iran ◽

Tectonic Control

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Upper Cenozoic sequences in the southeastern North Sea Basin

Bulletin of the Geological Society of Denmark ◽

10.37570/bgsd-1995-42-08 ◽

1995 ◽

Vol 42 ◽

pp. 74-95

Author(s):

Jan C. Sørensen ◽

Olaf Michelsen

Keyword(s):

North Sea ◽

Gamma Ray ◽

Sediment Accumulation ◽

Accumulation Rates ◽

The West ◽

Upper Cenozoic ◽

Lateral Extent ◽

Sequence Boundaries ◽

Maximum Flooding Surface ◽

Distinct Maximum

The Upper Cenozoic deposits, which cover the "mid-Miocene unconformity" in the southeastern North Sea Basin are subdivided into thirty-one sequences. Progradation from the east to the west is observed. The lowstand systems tracts appear seismically as prograding wedges. The top lowstand surface is recognized as a toplap surface in areas where high-angle progradation dominates the stratal pattern, indicating the presence of a bypass zone formed during lowstand progradation. The maximum flooding surface is identified on logs as a maximum gamma ray peak, which separates an upward fining from an upward coarsening trend. The two trends represent the transgressive and the highstand systems tracts, respectively. Sequence boundaries are commonly associated with widespread erosion. The presence of both fluvial and submarine erosion is interpreted on the basis of the orientation of incision and the position of erosion relative to the depositional shoreline break of the preceding sequence. In Late Miocene times the Ringkøbing-Fyn High partly separated the southeastern North Sea into two embayments, which were connected by a deep seaway towards the west. Sediment accumulation rates seem to have culminated during periods with decreasing palaeo-temperatures. During relatively cold periods, the sequences were deposited as prograding wedges with a limited lateral extent. Two periods with maximum palaeotemperatures are time-equivalent with the two most distinct maximum flooding surfaces and intervals characterized by low sediment accumulation rates.

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Key biogeochemical factors affecting soil carbon storage in <i>Posidonia</i> meadows

Biogeosciences Discussions ◽

10.5194/bgd-12-18913-2015 ◽

2015 ◽

Vol 12 (22) ◽

pp. 18913-18944 ◽

Cited By ~ 4

Author(s):

O. Serrano ◽

A. M. Ricart ◽

P. S. Lavery ◽

M. A. Mateo ◽

A. Arias-Ortiz ◽

...

Keyword(s):

Carbon Storage ◽

Abiotic Factors ◽

Sediment Accumulation ◽

Accumulation Rates ◽

Factors Affecting ◽

Fine Grained ◽

Sediment Content ◽

Seagrass Ecosystems ◽

Global Estimates ◽

Biogeochemical Factors

Abstract. Biotic and abiotic factors influence the accumulation of organic carbon (Corg) in seagrass ecosystems. We surveyed Posidonia sinuosa meadows growing in different water depths to assess the variability in the sources, stocks and accumulation rates of Corg. We show that over the last 500 years, P. sinuosa meadows closer to the upper limit of distribution (at 2–4 m depth) accumulated 3 to 4-fold higher Corg stocks (averaging 6.3 kg Corg m−2) at 3 to 4-fold higher rates (12.8 g Corg m−2 yr−1) compared to meadows closer to the deep limits of distribution (at 6–8 m depth; 1.8 kg Corg m−2 and 3.6 g Corg m−2 yr−1). In shallower meadows, Corg stores were mostly derived from seagrass detritus (88 % in average) compared to meadows closer to the deep limit of distribution (45 % on average). Also, sediment accumulation rates and fine-grained sediment content (< 0.125 mm) in shallower meadows (2.0 mm yr−1 and 9 %, respectively) were approximately 2-fold higher than in deeper meadows (1.2 mm yr−1 and 5 %, respectively). The Corg stocks and accumulation rates accumulated over the last 500 years in bare sediments (0.6 kg Corg m−2 and 1.2 g Corg m−2 yr−1) were 3 to 11-fold lower than in P. sinuosa meadows, while fine-grained sediment content (1 %) and seagrass detritus contribution to the Corg pool (20 %) were 8 and 3-fold lower than in Posidonia meadows, respectively. The patterns found support the hypotheses that Corg storage in seagrass soils is influenced by interactions of biological (e.g. meadow productivity, cover and density), chemical (e.g. recalcitrance of Corg stocks) and physical (e.g. hydrodynamic energy and sediment accumulation rates) factors within the meadow. We conclude that there is a need to improve global estimates of seagrass carbon storage accounting for biogeochemical factors driving variability within habitats.

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Accurate Lacustrine and Wetland Sediment Accumulation Rates Determined from 14C Activity of Bulk Sediment Fractions

Radiocarbon ◽

10.1017/s0033822200042843 ◽

2007 ◽

Vol 49 (2) ◽

pp. 983-992 ◽

Cited By ~ 9

Author(s):

W G Walker ◽

Gregg R Davidson ◽

Todd Lange ◽

Daniel Wren

Keyword(s):

Organic Material ◽

Radiocarbon Dating ◽

Sediment Accumulation ◽

Lacustrine Sediments ◽

Oxbow Lake ◽

Bulk Sediment ◽

Accumulation Rates ◽

Wetland Sediment ◽

Fine Grained ◽

Unknown Mixture

In the absence of identifiable macrofossils in lacustrine sediments, radiocarbon dating must rely on pollen or bulk sediment fractions. Bulk sediment fractions are not generally preferred because they contain an unknown mixture of organic material of variable age, they may contain dead carbon such as lignite that is difficult to eliminate, and material of aquatic origin may be subject to reservoir effects. If the various processes that contribute carbon to the system are relatively constant over time, however, changes in 14C activity with depth may be used to accurately estimate sediment accumulation rates even if the absolute ages are erroneous. In this study, fine-grained fractions (250–710 μm organic material, humic acids extracted from <250-μm fraction, and untreated <250-μm fraction combusted at low temperature) were analyzed and compared with terrestrial plant stems (twigs), charcoal, and wood fragments in sediments from an oxbow lake in Mississippi, USA. The 14C activities of the bulk fractions were highly linear with depth and produced consistent calculated sediment accumulation rates similar to, and perhaps more reliable than, rates determined using twigs or charcoal.

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New biostratigraphic data from the Lower Jurassic Fernie Formation in the subsurface of west-central Alberta and their stratigraphic implications

Canadian Journal of Earth Sciences ◽

10.1139/e02-096 ◽

2003 ◽

Vol 40 (1) ◽

pp. 45-63 ◽

Cited By ~ 12

Author(s):

Michèle Asgar-Deen ◽

Russell Hall ◽

Jim Craig ◽

Cynthia Riediger

Keyword(s):

British Columbia ◽

Red Deer ◽

Gamma Ray ◽

Lower Jurassic ◽

The West ◽

Fine Grained ◽

Poker Chip ◽

West Central ◽

Gamma Ray Log

Geophysical gamma-ray log responses and examination of cores from select wells of the lower Fernie Formation document important correlations of several new lithologic units recognized in the subsurface of west-central Alberta. Ammonite faunas and coccolith floras recovered from these cores are illustrated and provide new ages for several of these units, requiring a revision of their correlation with surface stratigraphy of the west-central Alberta foothills. The organic-rich, fine-grained west-central Alberta subsurface lower Fernie Formation sediments are Hettangian to late Toarcian in age and are, therefore, correlative with outcrops of unnamed basal Fernie strata of northeastern British Columbia, Nordegg Member cherty limestones of the Cadomin and Nordegg areas, and with the Red Deer Member and Poker Chip Shale at outcrop in west-central Alberta.

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Distribution of the Bandera Shale of the Marmaton Group, Middle Pennsylvanian of Southeastern Kansas

Current Research in Earth Sciences ◽

10.17161/cres.v0i241.11781 ◽

1998 ◽

pp. 29-41

Author(s):

Robert L. Brownfield ◽

Robert L. Brenner ◽

John P. Pope

Keyword(s):

Cross Sections ◽

Gamma Ray ◽

High Energy ◽

Sedimentary Characteristics ◽

Fine Grained ◽

Isopach Maps ◽

Marine Influence ◽

Carbonate Formations ◽

Gamma Ray Log ◽

Siliciclastic Sediments

In southeastern Kansas, the Middle Pennsylvanian (Desmoinesian) Bandera Shale consists of sandstone, shale, limestone, and coal deposited between two carbonate formations, the underlying Pawnee Limestone and the overlying Altamont Limestone. Isopach maps and cross sections indicate that the Bandera Shale thickens southeastward towards the Oklahoma and Missouri borders. Analysis of gamma-ray-log signatures, augmented by neutron-log signatures, indicates that the Bandera Shale is rich in mudstone, with sandstones limited to intervals ranging from 10 ft to 30 ft (3-9.1 m) in thickness. Comparisons with previously studied cored and logged siliciclastic portions of overlying Missourian lithologies suggest that the Bandera Shale consists of various proportions of sandstone, siltstone, clay-rich shale, and calcite-cemented sandstone. Exposures of the Bandera Shale in Bourbon County, Kansas, consist of interbedded shale and calcite-cemented, fine-grained sandstone. Sandstone beds, ranging from 3 cm to 20 cm (1.2-7.9 in) in thickness, are, in places, rhythmically laminated with organic-rich and organic-poor lamina forming 2-mm (0.8-in)-thick couplets. Many sandstone bedding surfaces in the lower and middle portion of the Bandera Shale are bioturbated with horizontal feeding trails and some vertical burrows that suggest marine environments. Thicker sandstone units are either trough cross-bedded, with sets up to 1.5 m (4.9 ft) thick, or amalgamated ripple cross-laminated and flaser-laminated. Outcrop observations coupled with subsurface analysis indicated that Bandera Shale in southeastern Kansas was deposited as a siliciclastic complex that prograded westward during a sea-level lowstand. Siliciclastic sediments may have been deposited in a clastic wedge or deltaic complex, but sedimentary characteristics observed in outcrops record marine influence at least along the margins of the complex. Rhythmic stratification within sandstone beds that are interbedded with shale resemble tidal features described elsewhere in the Pennsylvanian of North America and suggest that embayments were present where tidal cells were amplified along a morphologically irregular shoreline. Bioturbated sandstone units, interbedded with clay shale, record high-energy events that influenced sand distribution.

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