Lecture 10 - Ice Marginal sedimentation and landforms

Question 1

Benn (1989)

and

Evans and Hiemstra (2005)

shame shiz

Answer 1

Moraine Asymmetry correlated with the distribution of free facies in the valley

SupraG = passive transport, non modified clasts
(high RA and C40 values)

SubG = active transport, rounded and blockier clasts (low RA and C40 values)

Question 2

Boulton (1986)

Answer 2

local climate regime and mass balance state are important determinants of the dynamics of terrestrial and marine glacier fronts, determine the sediments and landforms produced at the G snout

glacier fluctuations determine the resultant distribution of many important masses of G sediment

marine/terrestrial environments of high activity glaciers - advance during winter producing push moraines BUT retreat during summer and form major ice contact fans

Question 3

Boulton (1986)

scenarios of land type

Answer 3

maritime climates = winter ‘push moraines’ produced during late winter advance

continental climate = no significant winter readvance, annual push-moraines are absent

terrestrial environments = push moraine formation accompanied by uplift, rejuvenation and down cutting of outwash systems, their sediments glacitectonised

Question 4

Boulton (1986) scenarios of velocity and calving

Answer 4

high velocity just exceeded by the calving rate = closely spaced push moraines

high velocity far exceeded by calving rate = closely spaced moraines but separate ice marginal fans

low velocity and high calving = well separated and feebly developed push moraines

low velocity and low calving rate = feeble push moraines and coalescent fans

Question 5

Mulder and Alexander (2001)

Answer 5

cohesive flows commonly referred to as debris flows and mud flows

turbidity flows and concentrated flows can be divided based on flow duration

flows with high and low sediment concentration may co-exist in one transport event - downslope transformations, flow stratification or shear layer development of the mixing interface with the overlying water

deposits of an individual flow event at one site may form from a succession of different flow types

flows along the floor can cause industrial, environmental and human distorters

Question 6

Mulder and Alexander (2001) density flows

Answer 6

many processes in subaqueous density flows and the deformation of soft sediment - makes it difficult to interpret the sedimentary record of mass flow processes

boundary between hyper concentrated and concentration density flows defined by change in particle behavior

density flows - important sediment transport mechanisms, contribute to construction of deep-sea fans and deltas
- responsible for a very large % of subaqueous sediment transport basin wards

Question 7

Evans (200(

Answer 7

controlled moraines = SupraG debris concentrations become hummocky moraine when the ice goes
- possess clear linearity due to inheritance of former pattern of debris rich ice

polythermal conditions are crucial to the concentration of supra glacial debris controlled moraines

end moraines lie on a process-form continuum constrained by basal and thermal regime