Introduction Flashcards
name 5 uses of paleo data
- Assess environmental changes in the absence of instrumental or historical records
- Provide evidence for change on a range of timescales, sometimes in a quantitative way
- Assess models of the past
- Provide baseline data for environmental managers
- Understand how ecosystems (multi-proxy) respond to different forcings
is geomorphological or sedimentary data usually more detailed?
sedimentary
what are clastic deposits
deposits made of inorganic components; broken up rocks
what is the name given to the mineral parts that make up clastic sediments?
clasts, which can range in
size from large boulders to very fine clays
what are biogenic sediments
sediments composed of the remains of plants and animals.
what are the 2 principal types of quartenary sediments
clastic and biogenic
are quaternary sediments usually consolidated or unconsolidated
unconsolidated
2 divisions of biogenic sediments
1) an organic component made up of humus and the decayed remains of plants and animals, and 2) an inorganic component made up of such elements as mollusc shells and diatom frustules.
difference between analysing sediment sections and sediment cores
sediment sections are open , exposed surfaces where stratigraphic variations are visible to the eye
sediment cores are where a core is recovered from below the ground surface, often from the deep ocean or lakes
name 3 common problems encountered in coring operations
(1) cores may be distorted during recovery or extrusion from the sampling chamber
(2) unless overlapping cores are taken, stratigraphic units that are either thin or of limited lateral extent may be missed during sampling
(3) it is often difficult to transport heavy coring equipment to remote areas where other logistical problems may also be encountered, such as a lack of water for hydraulic coring operations
which sediments are particularly vulnerable to distortion during recovery or extrusion of a core
poorly consolidated sediments, such as certain types of peat and lake muds
why is it difficult to ascertain sedimentary history of a site from just 1 core
most Quaternary sedimentary sequences, when traced laterally, vary in both thickness and complexity.
With many cores, a two-dimensional, or even three-dimensional, schematic model of lithological variability can be constructed
name the rapid, nondestructive, down-core scanning methods
photo-imaging, which provides a detailed and precise record of the lithological variations represented in the cores
enhanced imaging,
for example, X-radiography, often reveals important
lithological variations that are not clear to the naked
eye or shown by standard photography
other scanners can measure specific abundances, such as XRF, ITRX
which indicatory factors of a core are analysed in a lab
Particle size distribution Particle shape Surface textures of quartz particles Organic carbon content Metallic elements Heavy minerals Clay mineralogy Mineral magnetic analysis Stable isotope analysis
how is particle size distribution measured in coarse sediment?
seive analysis for coarser sediment
