|
| Samples in this core: |
| Sample link |
Core depth (cm) |
Lithology |
Facies interpretation |
Carbon type |
14C age |
| 3282 |
1.5 - 2.5 |
Bioturbated diatom ooze with abundant clasts (DO). High opal (20-25 percent), TOC content (>0.5 percent), and high water content (around 40-50 percent). Clasts include: Granite, rounded quartz, quartz, feldspars, dolerite, foliated/mylontic granitoids, basalt. High diatom abundance (1.4 * 10^9 valves/g). Benthic forams present. |
Pelagic sedimentation with ice rafted debris. General lack of terrigenous material. Thin bioturbated interval with abundant clasts suggests winnowing and current reworking (Domack et al., 1999) and is likely a condensed section. At the time of coring the site was 15 km south of the calving line, but was ~5km from the calving line when C-19 (a 200x32 km iceberg) calved off in 2002. This effectively places the CH-2 in the modern day 'calving zone' of the Ross Ice Shelf since the ice shelf became pinned to Ross Island during the glacial retreat. The presence of gravel clasts indicates open water with ice rafting must have existed at numerous time through the Holocene, as the base of the Ross Ice Shelf at this site was observed by video observations during hot water drilling to be free of basal debris. |
AIO |
13573.0 ± 50.0 |
| 3283 |
10.0 - 11.0 |
Bioturbated diatom ooze with abundant clasts (DO). High opal (20-25 percent), TOC content (>0.5 percent), and high water content (around 40- 50 percent). Clasts include: Granite, rounded quartz, quartz, feldspars, dolerite, foliated/mylontic granitoids, basalt. High diatom abundance (1.4 * 10^9 valves/g). Benthic forams present. |
Pelagic sedimentation with ice rafted debris. General lack of terrigenous material. Thin bioturbated interval with abundant clasts suggests winnowing and current reworking (Domack et al., 1999) and is likely a condensed section. At the time of coring the site was 15 km south of the calving line, but was ~5km from the calving line when C-19 (a 200x32 km iceberg) calved off in 2002. This effectively places the CH-2 in the modern day 'calving zone' of the Ross Ice Shelf since the ice shelf became pinned to Ross Island during the glacial retreat. The presence of gravel clasts indicates open water with ice rafting must have existed at numerous time through the Holocene, as the base of the Ross Ice Shelf at this site was observed by video observations during hot water drilling to be free of basal debris. |
AIO |
10074.0 ± 35.0 |
| 3284 |
17.0 - 18.0 |
Bioturbated diatom ooze with abundant clasts (DO). High opal (20-25 percent), TOC content (>0.5 percent), and high water content (around 40- 50 percent). Clasts include: Granite, rounded quartz, quartz, feldspars, dolerite, foliated/mylontic granitoids, basalt. High diatom abundance (1.4 * 10^9 valves/g). Benthic forams present. |
Pelagic sedimentation with ice rafted debris. General lack of terrigenous material. Thin bioturbated interval with abundant clasts suggests winnowing and current reworking (Domack et al., 1999) and is likely a condensed section. At the time of coring the site was 15 km south of the calving line, but was ~5km from the calving line when C-19 (a 200x32 km iceberg) calved off in 2002. This effectively places the CH-2 in the modern day 'calving zone' of the Ross Ice Shelf since the ice shelf became pinned to Ross Island during the glacial retreat. The presence of gravel clasts indicates open water with ice rafting must have existed at numerous time through the Holocene, as the base of the Ross Ice Shelf at this site was observed by video observations during hot water drilling to be free of basal debris. |
AIO |
16018.0 ± 55.0 |
| 3285 |
23.0 - 24.0 |
Bioturbated mud. Moderate opal (around 10), TOC content (around 0.25 percent), and high water content (around 50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Hemipelagic suspension settling. Bioturbation is the likely result of decrease sediment supply as the grounding line migrated away from the core site, allowing for the establishment of a benthos community (Domack et al., 1999; Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009). |
AIO |
25100.0 ± 150.0 |
| 3286 |
27.0 - 28.0 |
Bioturbated mud. Moderate opal (around 10), TOC content (around 0.25 percent), and high water content (around 50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Hemipelagic suspension settling. Bioturbation is the likely result of decrease sediment supply as the grounding line migrated away from the core site, allowing for the establishment of a benthos community (Domack et al., 1999; Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009). |
AIO |
31390.0 ± 310.0 |
| 3287 |
32.0 - 33.0 |
Bioturbated mud. Moderate opal (around 10), TOC content (around 0.25 percent), and high water content (around 50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Hemipelagic suspension settling. Bioturbation is the likely result of decrease sediment supply as the grounding line migrated away from the core site, allowing for the establishment of a benthos community (Domack et al., 1999; Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009). |
AIO |
28870.0 ± 230.0 |
| 3288 |
46.0 - 47.0 |
Mud with highly rhythmic, but faint submm- to mm-scale laminae defined by colour rather than obvious grainsize variations. Moderate opal (around 10 percent), TOC content (around 0.25 percent), and high water content (around 40-50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Rhythmic laminae suggest influence of traction currents reworking hemipelagic suspension settling sediments or turbidites . Rhythmites can also interpreted as meltwater plumes, but thin nature of facies, and lack of obvious size sorting argues against this interpretation, as plumites are often associated with large volume of subglacial meltwater release and high sedimentation rates (Cowan et al., 1999; McKay et al., 2009). Increased opal and TOC consistent with sub ice shelf setting (Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009) |
AIO |
32190.0 ± 350.0 |
| 3289 |
59.0 - 60.0 |
Mud with highly rhythmic, but faint submm- to mm-scale laminae and common gravel-sized clasts. Moderate opal (around 10), TOC content (around 0.25 percent), and high water content (around 45 percent). Clasts include: quartz, feldspars, granite,basalt, dolerite,metamorphic lithologies (foliated/mylontic granitoids, metasediments, marble). Benthic and planktonic forams present. Common diatoms (0.74 * 10^9 valves/g). |
Common diatom content and gravel clasts alongside the planktonic/benthic foraminifera suggests a short duration period of pelagic sedimentation in open water with iceberg rafting over the core site. Rhythmic laminae suggest traction currents reworking hemipelagic suspension settling sediments or turbidites (see facies Ml). We interpret that the input of terrigenous material has allowed this short-lived interval to be preserved in the stratigraphy, where as higher in the stratigraphic succession (e.g. Facies Mb), sediment starvation (due to a lack of terrigenous sediment supply) combined with bioturbation does not allow for the preservation of such events. |
AIO |
29130.0 ± 240.0 |
| 3290 |
71.0 - 72.0 |
Mud with highly rhythmic, but faint submm- to mm-scale laminae defined by colour rather than obvious grainsize variations. Moderate opal (around 10 percent), TOC content (around 0.25 percent), and high water content (around 40-50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Rhythmic laminae suggest influence of traction currents reworking hemipelagic suspension settling sediments or turbidites . Rhythmites can also interpreted as meltwater plumes, but thin nature of facies, and lack of obvious size sorting argues against this interpretation, as plumites are often associated with large volume of subglacial meltwater release and high sedimentation rates (Cowan et al., 1999; McKay et al., 2009). Increased opal and TOC consistent with sub ice shelf setting (Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009) |
AIO |
33210.0 ± 390.0 |
| 3291 |
75.0 - 76.0 |
Mud with highly rhythmic, but faint submm- to mm-scale laminae defined by colour rather than obvious grainsize variations. Moderate opal (around 10 percent), TOC content (around 0.25 percent), and high water content (around 40-50 percent). Clasts absent. Moderate diatom abundance (0.5 * 10^9 valves/g). |
Rhythmic laminae suggest influence of traction currents reworking hemipelagic suspension settling sediments or turbidites . Rhythmites can also interpreted as meltwater plumes, but thin nature of facies, and lack of obvious size sorting argues against this interpretation, as plumites are often associated with large volume of subglacial meltwater release and high sedimentation rates (Cowan et al., 1999; McKay et al., 2009). Increased opal and TOC consistent with sub ice shelf setting (Hemer and Harris, 2003). The lack of outsized clasts is indicative of depostion beneath an ice shelf lacking basal debris (Domack et al., 1999, Hemer and Harris, 2003; Mckay et al., 2009) |
AIO |
26240.0 ± 170.0 |
| 3292 |
79.0 - 80.0 |
Weakly-stratified muddy diamict with common granule-sized intraclasts of mud and diamict. TOC (0.27- 0.37 percent), low water content (25-30 percent). Clasts include: quartz, dolerite, granite,metamorphic lithologies (foliated/mylontic granitoids, metasediment, biotite schists, marble). Highly fragmented diatoms (0.4 * 10^9 valves/g). |
Glacimarine sediment deposited proximal to grounding line by melt out of subglacial basal debris. A lower sand content than Facies Dm suggest some water sorting during deposition, while the slightly elevated diatom abundance, water content and TOC compared to the underlying massive diamict suggest an increasing marine influence. (Domack et al., 1999). Common intraclasts are consistent with the granulated facies of Domack et al., 1999. |
AIO |
35250.0 ± 510.0 |
| 3293 |
88.0 - 89.0 |
Muddy Diamict, low opal (5 percent), TOC content (<0.25 percent), and low water content (around 15-20 percent). Clasts include: quartz, dolerite, granite,metamorphic lithologies (foliated/mylontic granitoids, metasediments, biotite schists, marble). Highly fragmented diatoms (0.3 * 10^9 valves/g). |
Subglacial transport and deposition in a subglacial or a grounding line proximal depositional setting (i.e. subglacial basal debris melt out). Lowest values of diatom and opal (but still high relative to other tills in antarctica, suggesting reworking of older diatom oozes), TOC and water content similar to other diamicts interpreted as tills elsewhere in the Ross Sea (Licht et al., 1996; Anderson, 1999; Domack et al., 1999, Mckay et al., 2008) and the Antarctic margin ((Smith et al., 2011)). |
AIO |
26210.0 ± 180.0 |
| 3294 |
101.0 - 102.0 |
Muddy Diamict, low opal (5 percent), TOC content (<0.25 percent), and low water content (around 15-20 percent). Clasts include: quartz, dolerite, granite,metamorphic lithologies (foliated/mylontic granitoids, metasediments, biotite schists, marble). Highly fragmented diatoms (0.3 * 10^9 valves/g). |
Subglacial transport and deposition in a subglacial or a grounding line proximal depositional setting (i.e. subglacial basal debris melt out). Lowest values of diatom and opal (but still high relative to other tills in antarctica, suggesting reworking of older diatom oozes), TOC and water content similar to other diamicts interpreted as tills elsewhere in the Ross Sea (Licht et al., 1996; Anderson, 1999; Domack et al., 1999, Mckay et al., 2008) and the Antarctic margin ((Smith et al., 2011)). |
AIO |
33050.0 ± 390.0 |
