This document discusses various proxies that can be used to reconstruct paleoclimate records from the Holocene epoch. It describes biotic proxies like diatoms, tree rings, pollens, corals, and phytoliths. Abiotic proxies discussed include ice cores, oxygen isotopes, lake and ocean sediments, speleothems, and x-ray diffraction. Specific proxies are then described in more detail, including how diatoms, tree rings, pollens, corals, oxygen isotopes, sediments, and x-ray diffraction can be analyzed to infer past climate conditions. A wide range of additional proxies are also listed.

1. Pankaj Kumar
M.Sc. {sem-2}
PROXIES
FOR
HOLOCENE
PALEOCLIMATE RECORDS

2. HOLOCENE
Holocene is a
geological epoch
Which is a part of
Quaternary period
that began after
Pleistocene at
approximately
11,700 years before
present.

3. Holocene has been identified with the current
known warm period known as MIS 1 and can be
considered as interglacial period in the current ice
age based on the evidences.
Holocene also encompasses the growth
and impacts of the human species &
Civilisation world-wide.

4. PROXY ?A measurement of one physical quantity
that is used as an indicator of the value
of another is called “Proxy”.
Or
The agency, function or tool of a deputy
that acts as a substitute for another is
known as the “Proxy”.

5. Paleoclimate proxies are physical, chemical and
biological materials preserved within the geologic
record .
These proxies can be analyzed and
correlated with climate or environmental
parameters in the modern world.
The use of a proxy to reconstruct past
climate requires an understanding of how that
proxy is related to some aspect of climate

6. PROXIES FOR PALEOCLIMATE
Biotic
 Diatoms
 Tree rings & Fossil
leaves
 Pollens & Spores
 Corals
 Phytoliths
etc.
Abiotic
 Ice cores
 Oxygen isotopes
 Lake & Ocean
Sediments
 Speleothems
 XRD
etc.

7. DIATOMS
Diatoms are photosynthetic golden brown unicellular algae
that form skeletons made of silica and are used extensively in
palaeoecological studies because they are excellent
indicators of past environmental conditions.
They are particularly useful palaeoecological proxies
because they can be identified to the species level using light
and scanning electron microscopy.
Diatoms have been used as
proxy indicators to reconstruct
Holocene climate variability
in every continent, and work on
continental aquatic ecosystems
has been much more common
than marine or coastal studies.

8. CLIMATIC CHANGES AND THE CORRESPONDING
RESPONSES IN THE DIATOM COMMUNITY.
prevailing climate Lake conditions Diatom responses
Cold Extened ice and Aerophillic diatoms
snow cover shallow water taxa
very small moat Low production
Moderate Moderate sized deeper water taxa
moat moderate production
Warm pelagic region of progressively more
lake is Ice-free deep water &
planktoni taxa
High production

9. TREE RINGS
Dendroclimatology is the
science of determining past
climates from trees, primarily
from properties of the annual
tree rings.
Trees and their unique rings
serve as proxy data Because
climate conditions influence tree
growth, patterns in tree-ring
widths, density, and isotopic
composition reflect variations in
climate.

10. POLLENS & SPORES
Pollen and spores are microscopic-sized structures that are
part of the reproductive cycle of plants. Pollen grains are
produced by seed plants (such as flowering plants and
conifers), and spores are produced by more primitive
vascular plants such as mosses and ferns.

11. Fossil pollen and spores
typically are dispersed from the
source plant by wind, insects,
and other means.
The oldest known land-plant
spores are of Upper Ordovician
age (~440 million years old).

12. CORALS
Corals are important reef
builders that live
primarily in tropical
oceans and secrete
calcium carbonate to
form a hard skeleton.
Corals are marine
invertebrates that
typically live in
colonies that contain
many individuals.

13. The carbonate contains isotopes of
oxygen as well as trace metals that can be
used to determine the temperature of the
water in which the coral grew.
Because corals build sequential layers,
they can be used to reconstruct changes in
water chemistry and temperature on an
annual to decadal scale.
 The oldest known corals are from
Cambrian rocks, deposited ~540 million
years ago.

14. OXYGEN ISOTOPES
Oxygen has three naturally occurring isotopes: 16O,
17O, and 18O, where the 16, 17 and 18 refer to the
atomic mass. The most abundant is 16O, with a small
percentage of 18O and an even smaller percentage of
17O.
Oxygen isotope analysis
considers only the ratio of
18O to 16O present in a
Sample.
The ratio of 18O to 16O in rain
or snow is controlled by temperature,
humidity and atmospheric circulation.

15. LAKE AND OCEAN SEDIMENTS
Proxy data can also be found on the floors of the
Earth’s oceans and lakes.
Billions of tons of Sediment
Accumulate in ocean and
lake basins each year,
providing a vast amount
of information about the
environment in them.
Scientists drill cores of the sediments from the
basin floors and examine their contents, which
include tiny fossils and chemicals, to interpret past
climates.

16. LIGHT BLUE DOTS SHOW LOCATIONS FROM WHICH OCEAN FLOOR SEDIMENT CORES HAVE
BEEN EXTRACTED.

17. Sediment records are usually extracted in the form of
long cores removed by drilling rigs similar to those
used to drill for oil.
The long sediment cores extracted from the ocean floor
have been cut into shorter segments and split lengthwise
down the middle.

18. X R D
X-ray powder diffraction (XRD) is an instrumental analytical technique,
which has been used to identify crystalline materials for almost a century.
The technique was originally used to examine the nature of crystal
lattices by the diffraction of X-rays through the closely spaced lattice of
atoms.
More recently, XRD has been used to reconstruct past climates from
fine-grained Late Holocene ponded sediments.
Climate sensitive clay minerals commonly occur in Late Holocene
sediments and their relative amounts correlate with climate episodes.The
quantification of clay minerals in sediments by XRD may be used as a
paleoclimatic proxy.

19. Relative percent composition of clays in Late Holocene
reservoir sediment is diagnostic of different mineral source
areas and their hydraulic transport processes,
which are climate controlled.
Climosequences of clay minerals from Late Holocene
reservoir sediments are correlative with magnetic
susceptibility records and provide a relatively simple and
cost-effective tool for gaining insight into paleoclimate.
X-ray diffractometer (XRD) unit can analyze a variety
of crystalline materials, including powders of various rock
types, soils, and crystals precipitated from solutions.
Software package PDXL is used to assist in identifying
peaks and matching mineral phases.

20. using typical glass microscope slides we can quickly
prepare many samples for analysis.
For more precise analyses, we use a single-crystal quartz
slide to eliminate background noise.
X-ray diffractometer with software package PDXL running on computer

21. Phytoliths
Ice cores
Speleothems
Boreholes
Paleotempestolog
Magnetic susceptibility
Charcoal
Clay mineralogy
Pseudoproxies
Historical data
etc.