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gure 4.13 Plastic cylinders (2.5 cm diameter) for paleomagnetic analysis inserted into varves at the rail line section.

Figure 38 gure 4.13 Plastic cylinders (2.5 cm diameter) for paleomagnetic analysis inserted into varves at the rail line section.

Related Figures (84)

1.1 Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet as well as the maximum extent of glacial Lake Columbia. Darker gray areas were swept by floodwaters from glacial Lake Missoula. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997).
1.1 Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet as well as the maximum extent of glacial Lake Columbia. Darker gray areas were swept by floodwaters from glacial Lake Missoula. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997).
Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet as well as the maximum extent of glacial Lake Columbia. LCFR: Lower Clark Fork River; MV: Mission Valley; NC: Ninemile Creek; RL: Rail line. Darker gray areas were swept by floodwaters from glacial Lake Missoula. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997). approximately 90 times during the Fraser Glaciation (Waitt, 1985; Atwater, 1986).
Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet as well as the maximum extent of glacial Lake Columbia. LCFR: Lower Clark Fork River; MV: Mission Valley; NC: Ninemile Creek; RL: Rail line. Darker gray areas were swept by floodwaters from glacial Lake Missoula. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997). approximately 90 times during the Fraser Glaciation (Waitt, 1985; Atwater, 1986).
ure 2.2 Stratigraphic log of the Ninemile Creek section, Montana.
ure 2.2 Stratigraphic log of the Ninemile Creek section, Montana.
Rhythmically bedded sand, silt, and clay units at the Ninemile Creek section. (A) One unit comprising sand-silt facies (below) and silt-clay facies (above). The contact between the two facies is gradational. Unit is 320 cm thick. Varves thin upward as the silt content decreases. (B) Gravel-sand facies at the base of a unit. Sand is ~6 cm thick. (C) Wedge-shaped feature at the top of a unit, infilled with gravel and sand. Feature is ~15 cm long. (D) Type-A and type-B climbing ripples in sand-silt facies. (E) Loaded silt laminae and water-escape structures in sand-silt facies. Figure 2.3
Rhythmically bedded sand, silt, and clay units at the Ninemile Creek section. (A) One unit comprising sand-silt facies (below) and silt-clay facies (above). The contact between the two facies is gradational. Unit is 320 cm thick. Varves thin upward as the silt content decreases. (B) Gravel-sand facies at the base of a unit. Sand is ~6 cm thick. (C) Wedge-shaped feature at the top of a unit, infilled with gravel and sand. Feature is ~15 cm long. (D) Type-A and type-B climbing ripples in sand-silt facies. (E) Loaded silt laminae and water-escape structures in sand-silt facies. Figure 2.3
Sedimentary features at the Ninemile Creek section. (A) Loaded lower part of unit with diapiric structure in gravel-sand facies and dish structures in the sand-silt facies. (B) Flame structures within lower part of sand-silt facies. (C) Nine varves with sharp lower contacts, gradational internal contacts, and internal laminations. (D) Event bed at the top of the silt-clay facies.
Sedimentary features at the Ninemile Creek section. (A) Loaded lower part of unit with diapiric structure in gravel-sand facies and dish structures in the sand-silt facies. (B) Flame structures within lower part of sand-silt facies. (C) Nine varves with sharp lower contacts, gradational internal contacts, and internal laminations. (D) Event bed at the top of the silt-clay facies.
Figure 2.6 Rhythmically bedded sand, silt, and clay units at the rail line section. Arrows indicate unit contacts. (A) A sedimentary unit comprising sand facies (below) and silt-clay facies (above). Varves thin upward as the silt content decreases. Square shows location of photo B. (B) Sand facies with type-A ripples and an erosional lower contact. Silt and clay varves are draped over ripples. (C) The basal sediment of the upper unit unconformably drapes the sediments of the unit below. The uppermost 2 cm of each unit were disturbed during draining of the lake. (D) Silt and clay varves. Note clay laminations within silt beds. Contacts between couplets and internal contacts are sharp and planar. Undulation of laminations are caused by post-depositional desiccation.
Figure 2.6 Rhythmically bedded sand, silt, and clay units at the rail line section. Arrows indicate unit contacts. (A) A sedimentary unit comprising sand facies (below) and silt-clay facies (above). Varves thin upward as the silt content decreases. Square shows location of photo B. (B) Sand facies with type-A ripples and an erosional lower contact. Silt and clay varves are draped over ripples. (C) The basal sediment of the upper unit unconformably drapes the sediments of the unit below. The uppermost 2 cm of each unit were disturbed during draining of the lake. (D) Silt and clay varves. Note clay laminations within silt beds. Contacts between couplets and internal contacts are sharp and planar. Undulation of laminations are caused by post-depositional desiccation.
Unique characteristics of sediments at the rail line section. (A) Laminated and rippled silt facies with clay laminations. Arrow indicates lower contact. (B) Largest wedge-shaped crack, measuring 15 by 26 cm. Crack is infilled with adjacent varved silt and clay. Varves are downturned toward the crack. Micro- faulting can be seen to the right of the wedge-shaped crack (squares). A secondary similar feature from the overlying unit crosscuts the main feature (arrows).
Unique characteristics of sediments at the rail line section. (A) Laminated and rippled silt facies with clay laminations. Arrow indicates lower contact. (B) Largest wedge-shaped crack, measuring 15 by 26 cm. Crack is infilled with adjacent varved silt and clay. Varves are downturned toward the crack. Micro- faulting can be seen to the right of the wedge-shaped crack (squares). A secondary similar feature from the overlying unit crosscuts the main feature (arrows).
“a: Sample aeptn Deneatn the ground Surtace. b K, U, and Th contents were determined using neutron-activation analysis of a dried and milled subsample of the bulk material sampled for dating. ¢ Aw: water content = water mass/mineral mass. For each sample, the as-collected water content was used in the dose rate calculation, with an uncertainty that is thought to account for any reasonable variation at 2 o. Sample depths, K, U, and Th contents, and water content.
“a: Sample aeptn Deneatn the ground Surtace. b K, U, and Th contents were determined using neutron-activation analysis of a dried and milled subsample of the bulk material sampled for dating. ¢ Aw: water content = water mass/mineral mass. For each sample, the as-collected water content was used in the dose rate calculation, with an uncertainty that is thought to account for any reasonable variation at 2 o. Sample depths, K, U, and Th contents, and water content.
Dose rates, equivalent doses, and optical ages.
Dose rates, equivalent doses, and optical ages.
(A) Flow chart showing the modified single-aliquot regenerative-dose (SAR) method used to date the rail line and Ninemile Creek samples. Li is the luminescence measured after administration of a regenerative dose, Di. In this case the regenerative doses (i= 1 to 5) were 15.9, 31.8. 63.6, 127.2, and 0 Gy; the 0 Gy data point is used to check for thermal transfer resulting from the preheat, which was 220 °C for 10 s. An aliquot was rejected if the luminescence measured at the 0 Gy step was more than 5 percent of that of the natural. Ti is the luminescence measured following a test dose of 12.7 Gy and a cut-heat of 160 °C. For each aliquot, the 15.9 Gy dose (arbitrary choice) was repeated to determine the effectiveness of the test dose for correcting for sensitivity change; only aliquots that had a recycling ratio within 10 percent of unity were accepted. (B) Example of a luminescence decay curve for an aliquot of sample MAH-3, which is typical of those generated from natural aliquots of the three samples. The initial measured signal is dominated by the thermally stable fast component, which decays to about 10 percent of its initial intensity in ~2 s. The inset graph shows dose-response data for this aliquot, determined from the sensitivity-corrected luminescence (Li/Ti) measured over the first 0.4 s of stimulation, minus that recorded during the last 20 s. The data are fitted with a saturating exponential curve, onto which the natural luminescence is interpolated in order to determine the equivalent dose Figure 2.8
(A) Flow chart showing the modified single-aliquot regenerative-dose (SAR) method used to date the rail line and Ninemile Creek samples. Li is the luminescence measured after administration of a regenerative dose, Di. In this case the regenerative doses (i= 1 to 5) were 15.9, 31.8. 63.6, 127.2, and 0 Gy; the 0 Gy data point is used to check for thermal transfer resulting from the preheat, which was 220 °C for 10 s. An aliquot was rejected if the luminescence measured at the 0 Gy step was more than 5 percent of that of the natural. Ti is the luminescence measured following a test dose of 12.7 Gy and a cut-heat of 160 °C. For each aliquot, the 15.9 Gy dose (arbitrary choice) was repeated to determine the effectiveness of the test dose for correcting for sensitivity change; only aliquots that had a recycling ratio within 10 percent of unity were accepted. (B) Example of a luminescence decay curve for an aliquot of sample MAH-3, which is typical of those generated from natural aliquots of the three samples. The initial measured signal is dominated by the thermally stable fast component, which decays to about 10 percent of its initial intensity in ~2 s. The inset graph shows dose-response data for this aliquot, determined from the sensitivity-corrected luminescence (Li/Ti) measured over the first 0.4 s of stimulation, minus that recorded during the last 20 s. The data are fitted with a saturating exponential curve, onto which the natural luminescence is interpolated in order to determine the equivalent dose Figure 2.8
Radial plots of De showing the distribution of equivalent doses determined from aliquots of samples (A) MAH-3, (B) MAH-5, and (C) MAH-8. More precise data plot farther from the origin. In each case, the gray bands, which are generated by the radial plot software, are centered on the weighted mean equivalent dose (De) values provided by the central age model (CAM). De values that plot within the gray bands are consistent with the mean at a 95 percent confidence interval. De values that showed poor recycling ratios or unacceptably high thermal transfer (recuperation) were not included in the CAM calculations. The uncertainty in the weighted mean De used in the age calculation is provided by CAM. Over-dispersion values are 25 + 4, 16 + 2, and 9.5 + 1.3 percent for samples MAH-3, -5, and -8, respectively. Figure 2.9
Radial plots of De showing the distribution of equivalent doses determined from aliquots of samples (A) MAH-3, (B) MAH-5, and (C) MAH-8. More precise data plot farther from the origin. In each case, the gray bands, which are generated by the radial plot software, are centered on the weighted mean equivalent dose (De) values provided by the central age model (CAM). De values that plot within the gray bands are consistent with the mean at a 95 percent confidence interval. De values that showed poor recycling ratios or unacceptably high thermal transfer (recuperation) were not included in the CAM calculations. The uncertainty in the weighted mean De used in the age calculation is provided by CAM. Over-dispersion values are 25 + 4, 16 + 2, and 9.5 + 1.3 percent for samples MAH-3, -5, and -8, respectively. Figure 2.9
Study area showing locations mentioned in the text and the approximate location of Figure 2. The figure shows the maximum extent of the Cordilleran ice sheet as well as the maximum extent of glacial Lake Columbia. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997).
Study area showing locations mentioned in the text and the approximate location of Figure 2. The figure shows the maximum extent of the Cordilleran ice sheet as well as the maximum extent of glacial Lake Columbia. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997).
Franklin D. Roosevelt Lake, Washington. White is current lake; grey is outline of glacial Lake Columbia at the 500 m as! level. Site symbols refer to the dominant lithofacies association at each site; other lithofacies associations may be present. A representative selection of sites is shown. Inset (A): photo of Lake Roosevelt looking north toward Sanpoil Valley. (Sanpoil Valley area of figure adapted from Atwater, 1986).
Franklin D. Roosevelt Lake, Washington. White is current lake; grey is outline of glacial Lake Columbia at the 500 m as! level. Site symbols refer to the dominant lithofacies association at each site; other lithofacies associations may be present. A representative selection of sites is shown. Inset (A): photo of Lake Roosevelt looking north toward Sanpoil Valley. (Sanpoil Valley area of figure adapted from Atwater, 1986).
Site 60, Lake Roosevelt. (A) Interbedded subaqueously deposited, poorly sorted, cobble-pebble gravel and coarse sand is overlain by subglacially deposited, poorly sorted, matrix-supported diamicton. A 1-3- m bed of subaqueous cobble gravel overlying this sequence is not visible in the photo. Bedded glaciolacustrine sandy silt caps the sediments. (B) Close-up view of the lower subaqueous outwash unit. Normally graded, planar inclined beds are overlain by normally graded horizontal beds with planar cross-bedding. Figure 3.3 Columbia River; the exposure is approximately 700 m long and 65 m high Figure 3.2). A 5/-m-high, ~900-m-long bluff along upper Columbia River Cedonia exposes, from base to top, gravel, diamicton, gravel, and sandy sil site 26B, south of (site 60, Figures 3.2 and 3.3). The gravel unit is 28 m thick, poorly sorted, and lightly rust- coloured (Figures 3.3A and 3.3B). It comprises cobble-pebble gravel with in erbedded coarse sand supporting outsized clasts up to 70 cm in diameter. The lower part of the gravel unit includes normally graded, planar inclined beds dipping 20—25° downvalley; these are overlain by normally graded horizontal beds with planar cross-bedding (Figure 3.3B). This lower unit is conformably overlain by 6 m of grey, poorly sorted, matrix- supported diamicton containing 25-30% clasts ranging from pebbles to small boulders 30 cm in diameter. The upper contact of the diamicton is erosive and is overlain by a 1-3 m-thick bed of poorly exposed cobble gravel. The upper 20 m of the exposure consists a ee er ok a er Mm: |
Site 60, Lake Roosevelt. (A) Interbedded subaqueously deposited, poorly sorted, cobble-pebble gravel and coarse sand is overlain by subglacially deposited, poorly sorted, matrix-supported diamicton. A 1-3- m bed of subaqueous cobble gravel overlying this sequence is not visible in the photo. Bedded glaciolacustrine sandy silt caps the sediments. (B) Close-up view of the lower subaqueous outwash unit. Normally graded, planar inclined beds are overlain by normally graded horizontal beds with planar cross-bedding. Figure 3.3 Columbia River; the exposure is approximately 700 m long and 65 m high Figure 3.2). A 5/-m-high, ~900-m-long bluff along upper Columbia River Cedonia exposes, from base to top, gravel, diamicton, gravel, and sandy sil site 26B, south of (site 60, Figures 3.2 and 3.3). The gravel unit is 28 m thick, poorly sorted, and lightly rust- coloured (Figures 3.3A and 3.3B). It comprises cobble-pebble gravel with in erbedded coarse sand supporting outsized clasts up to 70 cm in diameter. The lower part of the gravel unit includes normally graded, planar inclined beds dipping 20—25° downvalley; these are overlain by normally graded horizontal beds with planar cross-bedding (Figure 3.3B). This lower unit is conformably overlain by 6 m of grey, poorly sorted, matrix- supported diamicton containing 25-30% clasts ranging from pebbles to small boulders 30 cm in diameter. The upper contact of the diamicton is erosive and is overlain by a 1-3 m-thick bed of poorly exposed cobble gravel. The upper 20 m of the exposure consists a ee er ok a er Mm: |
Site 38, Lake Roosevelt. (A) Close-up view of diamicton that is massive, poorly sorted, and moderately compact with ~5 % subangular to subrounded clasts. (B) Part of the exposure showing one horizontal diamicton bed overlain by five diamicton beds dipping ~9 ° south. The diamicton beds are separated by beds of poorly sorted gravel, sand, and minor silt. that these deposits were overridden by a glacier.
Site 38, Lake Roosevelt. (A) Close-up view of diamicton that is massive, poorly sorted, and moderately compact with ~5 % subangular to subrounded clasts. (B) Part of the exposure showing one horizontal diamicton bed overlain by five diamicton beds dipping ~9 ° south. The diamicton beds are separated by beds of poorly sorted gravel, sand, and minor silt. that these deposits were overridden by a glacier.
Site 37, Lake Roosevelt. Massive, poorly sorted, moderately compact diamicton overlies and underlies trough and planar cross-bedded gravelly sand and silt. The diamicton pinches out to the south (right). The lower sand and silt unit contains lenses of similar diamicton that truncate the sand and silt. The diamicton lenses contains rip-ups of silt. One of the diamicton lenses has downvalley-oriented cross- beds and clasts along its lower contact. Figure 3.5
Site 37, Lake Roosevelt. Massive, poorly sorted, moderately compact diamicton overlies and underlies trough and planar cross-bedded gravelly sand and silt. The diamicton pinches out to the south (right). The lower sand and silt unit contains lenses of similar diamicton that truncate the sand and silt. The diamicton lenses contains rip-ups of silt. One of the diamicton lenses has downvalley-oriented cross- beds and clasts along its lower contact. Figure 3.5
Examples of subaqueous outwash deposited in front of the Columbia River lobe. (A) Clast-supported, planar-inclined, imbricated cobble gravel grades up into interbedded clast-supported, poorly sorted, pebble-cobble gravel and massive pebbly sand beds. This sequence is overlain by glaciolacustrine sand and silt. (B) Planar-inclined, matrix-supported, pebbly sand grades up into clast-supported, planar- inclined cobble gravel. These sediments are overlain by bedded sand and gravelly sand. (C) Bedded pebble-cobble gravel, sand, and silt. (D) Trough cross-bedded coarse to medium sand with interbedded massive fine sand. (E) Bedded and massive sand and silt with ice-rafted sediment (arrows). (F) Massive and bedded sand overlying pebble-cobble gravel. Sand is cross-cut by a vertically laminated dike (arrow). Figure 3.6
Examples of subaqueous outwash deposited in front of the Columbia River lobe. (A) Clast-supported, planar-inclined, imbricated cobble gravel grades up into interbedded clast-supported, poorly sorted, pebble-cobble gravel and massive pebbly sand beds. This sequence is overlain by glaciolacustrine sand and silt. (B) Planar-inclined, matrix-supported, pebbly sand grades up into clast-supported, planar- inclined cobble gravel. These sediments are overlain by bedded sand and gravelly sand. (C) Bedded pebble-cobble gravel, sand, and silt. (D) Trough cross-bedded coarse to medium sand with interbedded massive fine sand. (E) Bedded and massive sand and silt with ice-rafted sediment (arrows). (F) Massive and bedded sand overlying pebble-cobble gravel. Sand is cross-cut by a vertically laminated dike (arrow). Figure 3.6
Examples of gravelly sediment deposited in glacial Lake Columbia by glacial Lake Missoula floodwaters. (A) Clast-supported cobble gravel with downvalley planar-inclined bedding. The exposure is approximately 5 m high. (B) Normally graded, sandy, matrix-supported pebble-cobble gravel with downvalley planar-inclined bedding. The exposure is approximately 20 m high. (C) Normally graded, matrix-supported, pebble-cobble gravel with horizontal and downvalley planar-inclined bedding. Note the small boulder lag at the top of the gravel sequence. Gravels are overlain by glaciolacustrine bedded sand and silt. The exposure is approximately 19 m high. (D) A large sandy rip-up clast (~1 m long) in trough-crossbedded pebbly coarse sand. Figure 3.8
Examples of gravelly sediment deposited in glacial Lake Columbia by glacial Lake Missoula floodwaters. (A) Clast-supported cobble gravel with downvalley planar-inclined bedding. The exposure is approximately 5 m high. (B) Normally graded, sandy, matrix-supported pebble-cobble gravel with downvalley planar-inclined bedding. The exposure is approximately 20 m high. (C) Normally graded, matrix-supported, pebble-cobble gravel with horizontal and downvalley planar-inclined bedding. Note the small boulder lag at the top of the gravel sequence. Gravels are overlain by glaciolacustrine bedded sand and silt. The exposure is approximately 19 m high. (D) A large sandy rip-up clast (~1 m long) in trough-crossbedded pebbly coarse sand. Figure 3.8
Figure 3.9 Examples of sand and silt deposited in glacial Lake Columbia by glacial Lake Missoula floodwaters. (A) Five sand flood units bounded by silty varves near Hawk Creek. Flood units have loaded lower contacts, silt-rip-ups in the lower parts of the units, plane beds, and massive beds. Box highlights photo C. (B) One coarse sand flood bed at Hawk Creek. The flood bed has an erosive lower contact, contains beds with abundant silt rip-ups, and is sharply overlain by laminated silt. (C) Close up of part of photo A. Flood bed has a loaded lower contact with silt diapirs and silt rip-ups in the lower part of the unit. The flood bed grades upward to plane-bedded sand and silt. The entire sequence is draped by silty varves that were loaded and eroded by the subsequent flood. (D) Sandy climbing ripples in a flood bed, sharply overlain by massive silt, which grades upward into silty varves. The tool is 26.5 cm long. (E) One upward-fining flood bed. Plane-bedded sand grades upward successively to rippled sand, through interbedded sand and silt, laminated silt, and massive silt, to silty varves. The sequence is interrupted by a massive, brecciated silt bed (ZB) and a massive, reversely graded sand bed (SB). The shovel is ~1 mlona. (F) Trough cross-beds in a flood unit with beds of silt at the base. The tool is 26.5 cm long.
Figure 3.9 Examples of sand and silt deposited in glacial Lake Columbia by glacial Lake Missoula floodwaters. (A) Five sand flood units bounded by silty varves near Hawk Creek. Flood units have loaded lower contacts, silt-rip-ups in the lower parts of the units, plane beds, and massive beds. Box highlights photo C. (B) One coarse sand flood bed at Hawk Creek. The flood bed has an erosive lower contact, contains beds with abundant silt rip-ups, and is sharply overlain by laminated silt. (C) Close up of part of photo A. Flood bed has a loaded lower contact with silt diapirs and silt rip-ups in the lower part of the unit. The flood bed grades upward to plane-bedded sand and silt. The entire sequence is draped by silty varves that were loaded and eroded by the subsequent flood. (D) Sandy climbing ripples in a flood bed, sharply overlain by massive silt, which grades upward into silty varves. The tool is 26.5 cm long. (E) One upward-fining flood bed. Plane-bedded sand grades upward successively to rippled sand, through interbedded sand and silt, laminated silt, and massive silt, to silty varves. The sequence is interrupted by a massive, brecciated silt bed (ZB) and a massive, reversely graded sand bed (SB). The shovel is ~1 mlona. (F) Trough cross-beds in a flood unit with beds of silt at the base. The tool is 26.5 cm long.
Examples of glacial Lake Missoula sand and silt flood units in glacial Lake Columbia. (A) Climbing ripple-drift sequence grading upward into laminated silt with interbedded sand. (B) Climbing ripple-drift sequence sharply overlain by laminated silt. (C) Two sand flood beds separated by thin, loaded varved silt. The fine-grained flood facies are absent at this site. (D) Site 91 showing three flood beds (F1, F2, F3) separated by varves (GL). The lower flood bed comprises approximately 15 sand beds. (E) Close- up view of two beds in photo D. The lower bed shows differences in grading, crossbeds, and silt rip-ups. Flame structures at the top of the bed indicate loading by the overlying sand bed. (F) One of the four anomalous beds at site 67. The bed has an erosive lower contact, type-A ripples indicating upvalley flow, and has a pinkish colour different from that of the bounding varves. Figure 3.11
Examples of glacial Lake Missoula sand and silt flood units in glacial Lake Columbia. (A) Climbing ripple-drift sequence grading upward into laminated silt with interbedded sand. (B) Climbing ripple-drift sequence sharply overlain by laminated silt. (C) Two sand flood beds separated by thin, loaded varved silt. The fine-grained flood facies are absent at this site. (D) Site 91 showing three flood beds (F1, F2, F3) separated by varves (GL). The lower flood bed comprises approximately 15 sand beds. (E) Close- up view of two beds in photo D. The lower bed shows differences in grading, crossbeds, and silt rip-ups. Flame structures at the top of the bed indicate loading by the overlying sand bed. (F) One of the four anomalous beds at site 67. The bed has an erosive lower contact, type-A ripples indicating upvalley flow, and has a pinkish colour different from that of the bounding varves. Figure 3.11
€3.12 Glacial Lake Missoula lake-bottom sediment, displaying 22 varves. Note the reddish brown colour attributable to erosion of the local Belt-Purcell Supergroup rocks. waxing phase deposits, a scenario that likely exists in some of the sand-silt association During the waxing stage of a glacial outburst flood, a hyperpycnal flow will deposit an upward-coarsening basal unit; during the waning stage, the hyperpycnal flow will deposit a fining-upward sequence, commonly with climbing ripples (Mulder et al., 2003). A complete hyperpycnite would consist of both sequences, with the transition between the two corresponding to the maximum grain size and the peak discharge of the flood (Mulder et al., 2003). As in the case of the classic turbidite sequence, a complete hyperpycnite of this type is an exception. Mulder et al. (2003) suspect that basal truncation of hyperpycnite sequences may be more common than a complete sequence because discharge and velocity at the peak of the flood are high enough to erode the waxing phase deposits. a scenario that likely exists in some of the sand-silt association
€3.12 Glacial Lake Missoula lake-bottom sediment, displaying 22 varves. Note the reddish brown colour attributable to erosion of the local Belt-Purcell Supergroup rocks. waxing phase deposits, a scenario that likely exists in some of the sand-silt association During the waxing stage of a glacial outburst flood, a hyperpycnal flow will deposit an upward-coarsening basal unit; during the waning stage, the hyperpycnal flow will deposit a fining-upward sequence, commonly with climbing ripples (Mulder et al., 2003). A complete hyperpycnite would consist of both sequences, with the transition between the two corresponding to the maximum grain size and the peak discharge of the flood (Mulder et al., 2003). As in the case of the classic turbidite sequence, a complete hyperpycnite of this type is an exception. Mulder et al. (2003) suspect that basal truncation of hyperpycnite sequences may be more common than a complete sequence because discharge and velocity at the peak of the flood are high enough to erode the waxing phase deposits. a scenario that likely exists in some of the sand-silt association
Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet and of glacial Lake Columbia. Area flooded during draining of glacial Lake Missoula is shown in dark grey. LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RL: rail line; RB: River Bend. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997). al., 2000; Denlinger and O’Connell, 2010). A plume of finer sediment travelled northwarc along the coast of Washington and British Columbia (Gombiner et al., 2010). al., 2000; Denlinger and O’Connell, 2010). A plume of finer sediment travelled northward
Study area showing locations mentioned in the text. The figure shows the maximum extent of the Corailleran ice sheet and of glacial Lake Columbia. Area flooded during draining of glacial Lake Missoula is shown in dark grey. LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RL: rail line; RB: River Bend. (Figure adapted from Waitt, 1985; Atwater, 1986; Levish, 1997). al., 2000; Denlinger and O’Connell, 2010). A plume of finer sediment travelled northwarc along the coast of Washington and British Columbia (Gombiner et al., 2010). al., 2000; Denlinger and O’Connell, 2010). A plume of finer sediment travelled northward
Photos of one sedimentary unit from the four sites sampled for paleomagnetic analysis. Arrows indicate unit contacts. (A) Ninemile Creek. Rippled and laminated very fine sand and silt grades up into silt and clay glaciolacustrine varves. Unit is ~3.2 m thick. The lower contact is not visible. (B) Rail line. One unit comprising a rippled sand bed (below) and silt and clay glaciolacustrine varves (above). (C) Manila Creek. Lower flood sediments are characterized by a loaded lower contact and planar and inclined silt laminations. Flood sediments grade up into bedded silt and clay glaciolacustrine sediments. The tape measure is extended ~30 cm. (D) River Bend. Coarse silty ripple-drift cross-laminations grade up into undulating laminations, and then to massive fine silt. The reverse grading at the base is apparent from the difference in moisture content: coarsest silt, ~15-30 cm above the base of unit, is lightest in colour. The notebook is 19 cm long. Figure 4.3
Photos of one sedimentary unit from the four sites sampled for paleomagnetic analysis. Arrows indicate unit contacts. (A) Ninemile Creek. Rippled and laminated very fine sand and silt grades up into silt and clay glaciolacustrine varves. Unit is ~3.2 m thick. The lower contact is not visible. (B) Rail line. One unit comprising a rippled sand bed (below) and silt and clay glaciolacustrine varves (above). (C) Manila Creek. Lower flood sediments are characterized by a loaded lower contact and planar and inclined silt laminations. Flood sediments grade up into bedded silt and clay glaciolacustrine sediments. The tape measure is extended ~30 cm. (D) River Bend. Coarse silty ripple-drift cross-laminations grade up into undulating laminations, and then to massive fine silt. The reverse grading at the base is apparent from the difference in moisture content: coarsest silt, ~15-30 cm above the base of unit, is lightest in colour. The notebook is 19 cm long. Figure 4.3
Stratigraphic log of the Manila Creek section. See Figure 4.2 for legend.
Stratigraphic log of the Manila Creek section. See Figure 4.2 for legend.
Dominant sedimentary characteristics of glacial Lake Missoula flood beds at Manila Creek. Note bedded and laminated silt and clay in most photos. (A) An erosional contact between glaciolacustrine sediment (below) and glacial Lake Missoula flood sediment (above). (B) A loaded contact with a diapiric structure between glaciolacustrine sediment (below) and glacial Lake Missoula flood sediment (above). (C) Normally graded beds and laminations. Note the flame structures in one clay bed. (D) Internal deformation of one or multiple beds. Pencil is 14 cm long. (E) Clay rip-up clasts (arrows) and deformed laminations within the lower part of a flood bed. Knife is about 15 cm long. (F) Ball and pillow structures. (G) Micro-faulting within a flood bed. (H) Type-B climbing ripples indicating down-valley flow. Figure 4.6
Dominant sedimentary characteristics of glacial Lake Missoula flood beds at Manila Creek. Note bedded and laminated silt and clay in most photos. (A) An erosional contact between glaciolacustrine sediment (below) and glacial Lake Missoula flood sediment (above). (B) A loaded contact with a diapiric structure between glaciolacustrine sediment (below) and glacial Lake Missoula flood sediment (above). (C) Normally graded beds and laminations. Note the flame structures in one clay bed. (D) Internal deformation of one or multiple beds. Pencil is 14 cm long. (E) Clay rip-up clasts (arrows) and deformed laminations within the lower part of a flood bed. Knife is about 15 cm long. (F) Ball and pillow structures. (G) Micro-faulting within a flood bed. (H) Type-B climbing ripples indicating down-valley flow. Figure 4.6
Sedimentary characteristics of glaciolacustrine sediments at Manila Creek. (A) Laminated and bedded silt and clay. Beds are possible composite varves. (B) Type-B very fine sand ripples in glaciolacustrine sediment near the top of the Manila Creek exposure. northeastern Washington and western Idaho.” of the units contain type-A and type-B ripple-drift cross-lamination recording northward, or down-valley, flow (Figure 4.9D) and suggesting that the sediments were deposited in a matter of hours or less (Jopling and Walker, 1968; Allen, 1982; Ashley et al., 1982). The lower parts of three units contain ripple-drift cross-lamination indicative of southward, or up-valley, flow, recording initial flooding of the valley. About half of the units have a faint, possibly loaded contact between lower coarser silt and upper finer, generally massive silt. Glenn (1965, p. 180) concluded from petrographic data that the sediment was derived from the “Columbia River Basin east of the Yakima and Walla Walla Valleys and probably in the extensive area of granitic and metamorphic rocks in eS 2) ee Se Te en: Oe ne ns oe oy wee |:
Sedimentary characteristics of glaciolacustrine sediments at Manila Creek. (A) Laminated and bedded silt and clay. Beds are possible composite varves. (B) Type-B very fine sand ripples in glaciolacustrine sediment near the top of the Manila Creek exposure. northeastern Washington and western Idaho.” of the units contain type-A and type-B ripple-drift cross-lamination recording northward, or down-valley, flow (Figure 4.9D) and suggesting that the sediments were deposited in a matter of hours or less (Jopling and Walker, 1968; Allen, 1982; Ashley et al., 1982). The lower parts of three units contain ripple-drift cross-lamination indicative of southward, or up-valley, flow, recording initial flooding of the valley. About half of the units have a faint, possibly loaded contact between lower coarser silt and upper finer, generally massive silt. Glenn (1965, p. 180) concluded from petrographic data that the sediment was derived from the “Columbia River Basin east of the Yakima and Walla Walla Valleys and probably in the extensive area of granitic and metamorphic rocks in eS 2) ee Se Te en: Oe ne ns oe oy wee |:
Dominant sedimentary characteristics of flood beds at River Bend and Latwesen. (A) Loaded (arrows) contact. (B) Fine silt rip-up in the lower part of a flood bed. Note iron staining of the lower unit. (C) Loaded contact with silt lenses in the underlying flood unit. (D) Erosional contact (arrow) and type-B climbing ripples in silt. Knife is about 15 cm long. Figure 4.9
Dominant sedimentary characteristics of flood beds at River Bend and Latwesen. (A) Loaded (arrows) contact. (B) Fine silt rip-up in the lower part of a flood bed. Note iron staining of the lower unit. (C) Loaded contact with silt lenses in the underlying flood unit. (D) Erosional contact (arrow) and type-B climbing ripples in silt. Knife is about 15 cm long. Figure 4.9
0 Mount St. Helens set S tephra at Zillah, Washington. The tephra was subaerially deposited at the top of a flood rhythmite. Locations of samples collected for optical dating (AZT and BZT) are shown. The dashed line highlights the contact with the overlying flood unit. Block is ~30 x 20 x 20 cm.
0 Mount St. Helens set S tephra at Zillah, Washington. The tephra was subaerially deposited at the top of a flood rhythmite. Locations of samples collected for optical dating (AZT and BZT) are shown. The dashed line highlights the contact with the overlying flood unit. Block is ~30 x 20 x 20 cm.
a d: sample depth beneath the ground surface. b> K, U, and Th contents were determined using neutron-activation analysis of a dried and milled subsample of the bulk material sampled for dating. ¢ Aw: water content = water mass/mineral mass. For each sample, the as-collected water content was used in the dose rate calculation, with an uncertainty that is thought to account for any reasonable variation at 2 o. Sample depths, K, U, and Th contents, and water content.
a d: sample depth beneath the ground surface. b> K, U, and Th contents were determined using neutron-activation analysis of a dried and milled subsample of the bulk material sampled for dating. ¢ Aw: water content = water mass/mineral mass. For each sample, the as-collected water content was used in the dose rate calculation, with an uncertainty that is thought to account for any reasonable variation at 2 o. Sample depths, K, U, and Th contents, and water content.
Dose rates, equivalent doses, and optical ages.
Dose rates, equivalent doses, and optical ages.
Flow chart showing the modified single-aliquot regenerative-dose (SAR) method used to date the loess samples. Li is the luminescence measured after administering a regenerative dose, Dj. In this case the regenerative doses (i= 1 to 5) were 15.9, 31.8. 63.6, 127.2, and 0 Gy; the 0 Gy data point is used to check for thermal transfer resulting from the preheat, which was 220 °C for 10 s. An aliquot was rejected if the luminescence measured at the 0 Gy step was more than 5 percent of that of the natural. Ti is the luminescence measured following a test dose of 12.7 Gy and a cut-heat of 160 °C. For each aliquot, the 15.9 Gy dose (arbitrary choice) was repeated to determine the effectiveness of the test dose for correcting for sensitivity change; only aliquots that had a recycling ratio within 10 percent of unity were accepted. Figure 4.11 curves with a three-point running average to compare them to the reference curve.
Flow chart showing the modified single-aliquot regenerative-dose (SAR) method used to date the loess samples. Li is the luminescence measured after administering a regenerative dose, Dj. In this case the regenerative doses (i= 1 to 5) were 15.9, 31.8. 63.6, 127.2, and 0 Gy; the 0 Gy data point is used to check for thermal transfer resulting from the preheat, which was 220 °C for 10 s. An aliquot was rejected if the luminescence measured at the 0 Gy step was more than 5 percent of that of the natural. Ti is the luminescence measured following a test dose of 12.7 Gy and a cut-heat of 160 °C. For each aliquot, the 15.9 Gy dose (arbitrary choice) was repeated to determine the effectiveness of the test dose for correcting for sensitivity change; only aliquots that had a recycling ratio within 10 percent of unity were accepted. Figure 4.11 curves with a three-point running average to compare them to the reference curve.
Remanence, magnetic susceptibility and median destructive field (MDF) ranges for all four sample sites.
Remanence, magnetic susceptibility and median destructive field (MDF) ranges for all four sample sites.
Radial plots showing the distribution of equivalent doses determined from aliquots of samples (A) AZT and (B) BZT. More precise data plot farther from the origin. In each case, the gray bands, whose widths (standard estimates) are generated by the radial plot software, are centered on the weighted mean equivalent dose (De) values provided by the central age model (CAM). De values that plot within the gray bands are consistent with the mean at a 95 percent confidence interval. Aliquots that generated luminescence showing poor fast components or dominant medium components were not accepted, and aliquots that showed poor recycling ratios or unacceptably high thermal transfer (recuperation) in their dose-response data were not included in the CAM calculations. The uncertainty in the weighted mean De used in the age calculation is provided by the CAM. Over-dispersion values are 21 + 3 and 49 + 9 percent for samples AZT and BZT, respectively.
Radial plots showing the distribution of equivalent doses determined from aliquots of samples (A) AZT and (B) BZT. More precise data plot farther from the origin. In each case, the gray bands, whose widths (standard estimates) are generated by the radial plot software, are centered on the weighted mean equivalent dose (De) values provided by the central age model (CAM). De values that plot within the gray bands are consistent with the mean at a 95 percent confidence interval. Aliquots that generated luminescence showing poor fast components or dominant medium components were not accepted, and aliquots that showed poor recycling ratios or unacceptably high thermal transfer (recuperation) in their dose-response data were not included in the CAM calculations. The uncertainty in the weighted mean De used in the age calculation is provided by the CAM. Over-dispersion values are 21 + 3 and 49 + 9 percent for samples AZT and BZT, respectively.
Equal-area, natural remanent magnetization (NRM) intensity, and orthogonal Zijderveld plots of alternating field demagnetization of NRM for pilot samples from (A) Ninemile Creek, (B) rail line, (C) Manila Creek, (D) River Bend, and (E) Latwesen. M/Mmax is the normalized magnetic intensity and MDF is the median destructive field of NRM. A weak viscous component was removed from most samples in fields of 10 to 20 milliTeslas (mT). (F) Example of a sample from the rail line section that was not completely demagnetized with stepwise alternating field demagnetization techniques. Figure 4.14
Equal-area, natural remanent magnetization (NRM) intensity, and orthogonal Zijderveld plots of alternating field demagnetization of NRM for pilot samples from (A) Ninemile Creek, (B) rail line, (C) Manila Creek, (D) River Bend, and (E) Latwesen. M/Mmax is the normalized magnetic intensity and MDF is the median destructive field of NRM. A weak viscous component was removed from most samples in fields of 10 to 20 milliTeslas (mT). (F) Example of a sample from the rail line section that was not completely demagnetized with stepwise alternating field demagnetization techniques. Figure 4.14
€4.15 Orthogonal plot of sample LKDO60 (Figure 14(D)) from the River Bend section, displaying principal component analysis forced through the origin. Demagnetization steps are 0, 10, 20, 30, 40, 50, 60, 80, and 100 mT. Principle component analysis was only applied to steps 20 to 100 mT.
€4.15 Orthogonal plot of sample LKDO60 (Figure 14(D)) from the River Bend section, displaying principal component analysis forced through the origin. Demagnetization steps are 0, 10, 20, 30, 40, 50, 60, 80, and 100 mT. Principle component analysis was only applied to steps 20 to 100 mT.
16 Fisherian mean orientation of (A) five samples from a Manila Creek glaciolacustrine unit and (B) five samples from a Manila Creek flood unit.
16 Fisherian mean orientation of (A) five samples from a Manila Creek glaciolacustrine unit and (B) five samples from a Manila Creek flood unit.
7 Cross-correlation of non-smoothed remanence directions from the River Bend (black squares) and Latwesen (grey circles) sections. The gap in the River Bend data represents one unit from which the data were deemed unacceptable based on stratigraphic and sedimentological observations. Note the shallower inclination values in the River Bend data. Figure 4.17
7 Cross-correlation of non-smoothed remanence directions from the River Bend (black squares) and Latwesen (grey circles) sections. The gap in the River Bend data represents one unit from which the data were deemed unacceptable based on stratigraphic and sedimentological observations. Note the shallower inclination values in the River Bend data. Figure 4.17
Remanence directions for Manila Creek. The shapes of the PSV curves are similar for both types of deposits, but more data had to be rejected for the flood-deposited units (black circles) than for the glaciolacustrine ones (grey squares). There appears to be significant inclination shallowing in some of the flood-deposited beds, especially near the top of the section. The blue line represents the expected inclination due to a geocentric axial dipole.
Remanence directions for Manila Creek. The shapes of the PSV curves are similar for both types of deposits, but more data had to be rejected for the flood-deposited units (black circles) than for the glaciolacustrine ones (grey squares). There appears to be significant inclination shallowing in some of the flood-deposited beds, especially near the top of the section. The blue line represents the expected inclination due to a geocentric axial dipole.
4.19 (A) Declination and (B) inclination records for the Ninemile Creek, rail line, Manila Creek, and Latwesen sections. Records were smoothed with a three-point running average and plotted with 95% confidence limits. The blue line represents the expected inclination due to a geocentral axial dipole.
4.19 (A) Declination and (B) inclination records for the Ninemile Creek, rail line, Manila Creek, and Latwesen sections. Records were smoothed with a three-point running average and plotted with 95% confidence limits. The blue line represents the expected inclination due to a geocentral axial dipole.
Correlation between the Ninemile Creek magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Ninemile site by virtual geomagnetic poles. The number of years between flood events for this correlation is 20-60 years. The blue line represents the expected inclination due to a geocentric axial dipole. Note the inclination shallowing toward the base of the Ninemile Creek section.
Correlation between the Ninemile Creek magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Ninemile site by virtual geomagnetic poles. The number of years between flood events for this correlation is 20-60 years. The blue line represents the expected inclination due to a geocentric axial dipole. Note the inclination shallowing toward the base of the Ninemile Creek section.
Correlation between the rail line magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the rail line site by virtual magnetic poles. The number of years between flood events for this correlation is 55-80 years. The blue line represents the expected inclination due to a geocentral axial dipole. Note the inclination shallowing throughout most of the rail line section.
Correlation between the rail line magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the rail line site by virtual magnetic poles. The number of years between flood events for this correlation is 55-80 years. The blue line represents the expected inclination due to a geocentral axial dipole. Note the inclination shallowing throughout most of the rail line section.
Correlation between the Manila Creek magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Manila Creek site by virtual magnetic poles. The number of years between flood events for this correlation is 55 years. The blue line represents the expected inclination due to a geocentral axial dipole. Note the inclination shallowing towards the base of the Manila Creek section.
Correlation between the Manila Creek magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Manila Creek site by virtual magnetic poles. The number of years between flood events for this correlation is 55 years. The blue line represents the expected inclination due to a geocentral axial dipole. Note the inclination shallowing towards the base of the Manila Creek section.
} Correlation between the Latwesen magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Latwesen site by virtual magnetic poles. The number of years between flood events for this correlation is 35 years. The blue line represents the expected inclination due to a geocentral axial dipole.
} Correlation between the Latwesen magnetic declination and inclination curves and the Fish Lake - Mono Lake reference curve. The reference curve was adjusted to the Latwesen site by virtual magnetic poles. The number of years between flood events for this correlation is 35 years. The blue line represents the expected inclination due to a geocentral axial dipole.
4 Examples of luminescence decay curves for aliquots (14 and 12, respectively) of samples (A) AZT and (B) BZT. Both decay curves are typical of those generated from natural aliquots. The inset graphs show dose-response data for these aliquots, determined from the sensitivity-corrected luminescence (L/T)) measured over the first 0.4 s of stimulation, minus that recorded during the last 20 s. The data are fitted with a saturating exponential curve, onto which the natural luminescence is interpolated in order to determine the equivalent dose (De). (A) The initial measured signal shown on the luminescence decay curve is dominated by the thermally stable fast component, which decays rapidly to about 10 percent of its initial intensity in~10 s. (B) The initial measured signal shown on the luminescence decay curve displays a pronounced unstable medium component, which takes longer (~20 s) to decay to about 10 percent of its initial intensity. The background level is higher in sample BZT than sample AZT, indicating the presence of a thermally unstable slow component.
4 Examples of luminescence decay curves for aliquots (14 and 12, respectively) of samples (A) AZT and (B) BZT. Both decay curves are typical of those generated from natural aliquots. The inset graphs show dose-response data for these aliquots, determined from the sensitivity-corrected luminescence (L/T)) measured over the first 0.4 s of stimulation, minus that recorded during the last 20 s. The data are fitted with a saturating exponential curve, onto which the natural luminescence is interpolated in order to determine the equivalent dose (De). (A) The initial measured signal shown on the luminescence decay curve is dominated by the thermally stable fast component, which decays rapidly to about 10 percent of its initial intensity in~10 s. (B) The initial measured signal shown on the luminescence decay curve displays a pronounced unstable medium component, which takes longer (~20 s) to decay to about 10 percent of its initial intensity. The background level is higher in sample BZT than sample AZT, indicating the presence of a thermally unstable slow component.
Study area showing locations mentioned in the text. LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RB: River Bend. Dark grey areas were swept by floodwaters from glacial Lake Missoula. The figure has been adapted from Waitt (1985), Atwater (1986), and Levish (1997). Craig, 1987; O’Connor and Baker, 1992; Denlinger and O’Connell, 2010).
Study area showing locations mentioned in the text. LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RB: River Bend. Dark grey areas were swept by floodwaters from glacial Lake Missoula. The figure has been adapted from Waitt (1985), Atwater (1986), and Levish (1997). Craig, 1987; O’Connor and Baker, 1992; Denlinger and O’Connell, 2010).
Photographs of units at each of the study sites. (A) A single unit at Ninemile Creek that is about 3.3 m thick. The lower part of the unit consists of rippled and laminated fine sand and silt. This sediment grades up into silt and clay varves. (B) One flood and one glaciolacustrine unit at Manila Creek. The lower flood sediment is characterized by a loaded lower contact and planar and inclined silt and clay laminations. The flood sediments grade up into glaciolacustrine, laminated clayey silt. The tape measure is about 30 cm long. (C) One unit at River Bend. The lower contact is erosional. Reversely graded silt and sand at the base of the unit grades upward into ripple-drift cross-laminated sand. The remainder of the unit is normally graded from sand to very fine silt. The field book is 19 cm long. Figure 5.2
Photographs of units at each of the study sites. (A) A single unit at Ninemile Creek that is about 3.3 m thick. The lower part of the unit consists of rippled and laminated fine sand and silt. This sediment grades up into silt and clay varves. (B) One flood and one glaciolacustrine unit at Manila Creek. The lower flood sediment is characterized by a loaded lower contact and planar and inclined silt and clay laminations. The flood sediments grade up into glaciolacustrine, laminated clayey silt. The tape measure is about 30 cm long. (C) One unit at River Bend. The lower contact is erosional. Reversely graded silt and sand at the base of the unit grades upward into ripple-drift cross-laminated sand. The remainder of the unit is normally graded from sand to very fine silt. The field book is 19 cm long. Figure 5.2
a LAT = Latwesen; MC = Manila Creek; NC = Ninemile Creek; RB = River Bend > Symbols relate to figures 5.5-5.10. Curie temperatures and inferred magnetic mineralogy of samples analysed for temperature-dependent susceptibility.
a LAT = Latwesen; MC = Manila Creek; NC = Ninemile Creek; RB = River Bend > Symbols relate to figures 5.5-5.10. Curie temperatures and inferred magnetic mineralogy of samples analysed for temperature-dependent susceptibility.
Thermomagnetic curves from (A) Ninemile Creek, (B) Manila Creek, and (C) Willamette Valley. Curves of coarser grained samples (turbidity currents at Ninemile Creek and flood units at Manila Creek and in the Willamette Valley) are black; curves of finer grained samples (glaciolacustrine units) are grey. Curves were translated to zero at high temperatures, and susceptibilities were normalised to the susceptibility at 52 °C. Figure 5.3
Thermomagnetic curves from (A) Ninemile Creek, (B) Manila Creek, and (C) Willamette Valley. Curves of coarser grained samples (turbidity currents at Ninemile Creek and flood units at Manila Creek and in the Willamette Valley) are black; curves of finer grained samples (glaciolacustrine units) are grey. Curves were translated to zero at high temperatures, and susceptibilities were normalised to the susceptibility at 52 °C. Figure 5.3
Examples of heating and cooling thermomagnetic curves from (A) Manila Creek, (B) Willamette Valley, and (C) Ninemile Creek. Black lines are heating curves; grey lines are cooling curves. Curves were translated to zero at high temperatures. Figure 5.4
Examples of heating and cooling thermomagnetic curves from (A) Manila Creek, (B) Willamette Valley, and (C) Ninemile Creek. Black lines are heating curves; grey lines are cooling curves. Curves were translated to zero at high temperatures. Figure 5.4
a MC = Manila Creek; NC = Ninemile Creek; RB = River Bend. > Symbols relate to figures 5.5-5.10. Range of hysteresis parameters.
a MC = Manila Creek; NC = Ninemile Creek; RB = River Bend. > Symbols relate to figures 5.5-5.10. Range of hysteresis parameters.
Grain size vs. volumetric magnetic susceptibility (K) plotted on log (A) and linear (B) plots. For each depositional setting, K, or the concentration of magnetite, is directly proportional to grain size. The colours show a change in median grain size from 1.2 um (red) to 78 zum (dark blue). Results from samples collected through three units at River Bend. The stratigraphic column at the left shows major sedimentological units. Parameters displayed are median grain size (Dso), natural remanent magnetization (NRM), magnetic susceptibility (K), paramagnetic susceptibility (ye), inclination, saturation magnetization (Js), saturation remanence (Jrs), coercive force (Hc), coercivity of remanence (Hcr), Superparamagnetic magnetization (Jspy), S-ratio, shape parameter (T), and the corrected anisotropy degree (P.). The vertical line on the inclination plot represents the expected inclination for a geocentric axial dipole. The colours show a change in median grain size from 1.2 4am (red) to 78 um (dark blue). See Figure 5 for legend.
Grain size vs. volumetric magnetic susceptibility (K) plotted on log (A) and linear (B) plots. For each depositional setting, K, or the concentration of magnetite, is directly proportional to grain size. The colours show a change in median grain size from 1.2 um (red) to 78 zum (dark blue). Results from samples collected through three units at River Bend. The stratigraphic column at the left shows major sedimentological units. Parameters displayed are median grain size (Dso), natural remanent magnetization (NRM), magnetic susceptibility (K), paramagnetic susceptibility (ye), inclination, saturation magnetization (Js), saturation remanence (Jrs), coercive force (Hc), coercivity of remanence (Hcr), Superparamagnetic magnetization (Jspy), S-ratio, shape parameter (T), and the corrected anisotropy degree (P.). The vertical line on the inclination plot represents the expected inclination for a geocentric axial dipole. The colours show a change in median grain size from 1.2 4am (red) to 78 um (dark blue). See Figure 5 for legend.
Hysteresis ratios for the four datasets shown on a Day plot. SD + MD and SP + SD mixing lines are from Dunlop (2002a). MD: multi-domain; SD: single domain; SP: superparamagnetic. The colours show a change in median grain size from 1.2 yum (red) to 78 um (dark blue). The arrows indicate the top three samples in the two Manila Creek flood units (red = lower unit; green = upper unit).
Hysteresis ratios for the four datasets shown on a Day plot. SD + MD and SP + SD mixing lines are from Dunlop (2002a). MD: multi-domain; SD: single domain; SP: superparamagnetic. The colours show a change in median grain size from 1.2 yum (red) to 78 um (dark blue). The arrows indicate the top three samples in the two Manila Creek flood units (red = lower unit; green = upper unit).
a MC = Manila Creek (datasets 1 and 2); NC = Ninemile Creek; RB = River Bend. > Symbols relate to figures 5.5-5.10. Average anisotropy of magnetic susceptibility parameters.
a MC = Manila Creek (datasets 1 and 2); NC = Ninemile Creek; RB = River Bend. > Symbols relate to figures 5.5-5.10. Average anisotropy of magnetic susceptibility parameters.
Summary of key magnetic properties for each depositional environment.?
Summary of key magnetic properties for each depositional environment.?
0.11 Flood (F) and glaciolacustrine (GL) sediments at Manila Creek. (A) The transition zone (TZ) between flood and glaciolacustrine sediments is characterized by massive, very fine silt to clay. (B) The transition zone has a pinkish tinge similar to fine-grained, hematite-bearing, glacial Lake Missoula sediments at Ninemile (see Figure 5.2).
0.11 Flood (F) and glaciolacustrine (GL) sediments at Manila Creek. (A) The transition zone (TZ) between flood and glaciolacustrine sediments is characterized by massive, very fine silt to clay. (B) The transition zone has a pinkish tinge similar to fine-grained, hematite-bearing, glacial Lake Missoula sediments at Ninemile (see Figure 5.2).
NRM and K for the lowest 25 units at Manila Creek. Glaciolacustrine samples are black; flood samples are grey. Gaps in the data represent samples that were discarded because their values were unacceptable. Dashed horizontal lines delineate the base of flood units. Note the gradual decrease in both NRM and K across erosional contacts at the base of the flood units (red arrows) and the sudden increase in NRM and K in the transition from flood units into glaciolacustrine units.
NRM and K for the lowest 25 units at Manila Creek. Glaciolacustrine samples are black; flood samples are grey. Gaps in the data represent samples that were discarded because their values were unacceptable. Dashed horizontal lines delineate the base of flood units. Note the gradual decrease in both NRM and K across erosional contacts at the base of the flood units (red arrows) and the sudden increase in NRM and K in the transition from flood units into glaciolacustrine units.
a HC: Hawk Creek; LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RL: rail line; ZH: Zillah. > This age refers to the age of Mount St. Helens set S tephra based on the Manila Creek PSV correlation. ¢ OD: optical dating; PSV: paleomagnetic secular variation correlation; RD: radiocarbon dating. 4 Indicates that the age was converted from optical calendar age at the two-sigma range to radiocarbon age. See specific chapters for details. Corresponding ages are only included where they were calculated in specific chap Summary of ages, dating methods, and key results.
a HC: Hawk Creek; LAT: Latwesen; MC: Manila Creek; NC: Ninemile Creek; RL: rail line; ZH: Zillah. > This age refers to the age of Mount St. Helens set S tephra based on the Manila Creek PSV correlation. ¢ OD: optical dating; PSV: paleomagnetic secular variation correlation; RD: radiocarbon dating. 4 Indicates that the age was converted from optical calendar age at the two-sigma range to radiocarbon age. See specific chapters for details. Corresponding ages are only included where they were calculated in specific chap Summary of ages, dating methods, and key results.
Appendix F. Magnetic parameters for samples plotted in figures 5.5, 5.6, 5.7, and 5.8
Appendix F. Magnetic parameters for samples plotted in figures 5.5, 5.6, 5.7, and 5.8
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