stromatolites, Precambrian stromatolites , Cambrian stromatolites, Indian stromatolites and threats to stromatolites

1. PRESENTED BY :
MUHAMMAD BILAL
UNIVERSITY OF EDUCATION, LAHORE
Stromatolites

2. STROMATOLITES
Stromatolites are living fossils and the oldest living lifeforms on our
planet. The name derives from the Greek, stroma, meaning
“mattress”, and lithos, meaning “rock”. Stromatolite literally means
“layered rock”.
Stromatolites are layered mounds, columns, and sheet-like
sedimentary rocks. They were originally formed by the growth of
layer upon layer of cyanobacteria.
Cyanobacteria were ultimately responsible for one of the most
important "global changes" that the Earth has undergone. Being
photosynthetic, cyanobacteria produce oxygen as a by-product.

3. • Before cyanobacteria the air was only 1%
oxygen. Then photosynthesising Stromatolites
pumped oxygen into the oceans. When the
oceans’ waters were saturated, oxygen was
released into the air, and with around 20% of
oxygen in the air, life was able to flourish and
evolve.
• As stromatolites became more common 2.5
billion years ago, they gradually changed the
Earth's atmosphere from a carbon dioxide-rich
mixture to the present-day oxygen-rich
atmosphere.

4. WHERE DO STROMATOLITES LIVE
• Living Stromatolites are no longer widely distributed.
There are only two well-developed marine Stromatolite
areas in the world: in the Bahamas and at Hamelin
Pool in the Shark Bay area of Western Australia
• Australia’s marine Stromatolites are protected: they're
part of the Hamelin Pool Marine Nature Reserve, which
lies within the UNESCO World Heritage listed Shark
Bay.
The Stromatolites of Hamelin
Pool at sunset

5. FOSSIL RECORD
• Stromatolites are a major constituent of the fossil record
of the first forms of life on earth. They peaked about
1.25 billion years ago and subsequently declined in
abundance and diversity, so that by the start of the
Cambrian they had fallen to 20% of their peak.
• The most widely supported explanation is that
stromatolite builders fell victim to grazing creatures (the
Cambrian substrate revolution); this theory implies that
sufficiently complex organisms were common over 1
billion years ago.
• Another hypothesis is that protozoans like the
foraminifera were responsible for the decline.
In the rock record, stromatolites can be
recognized by characteristic laminar
structures,

6. PRECAMBRIAN STROMATOLITES
 Archaean stromatolites
• Stromatolites are relatively scarce in the Archaean until nearly
the end of the eon.
• Earlier it was believed that 3,496 Ma old domical and conical
stromatolites from the Dresser Formation of the Pilbara Craton
(Western Australia) are the oldest convincing evidence for life on
Earth.
• Recently, reported evidence for ancient life from a newly
exposed outcrop of 3,700- Myr-old metacarbonates rocks in the
Isua Supracrustal Belt (ISB), southwest Greenland.
• These metacarbonates rocks contain 1–4-cm-high stromatolites
produced by microbial communities.
Dresser Formation - Pilbara
Isua Supracrustal Belt

7. • Paleoarchean and Mesoarchean stromatolites were rare and not
diverse.
• In the Neoarchean about 2.7-2.8 Ga, stromatolites were more
abundant and much more diverse.
• This may have resulted from the formation of extensive continental
shelves.
• This can be established from the rise of prominence of columnar
forms and especially ministromatolites with a radial fibrous fabric in
the Neoarchean, which are characteristic of peri tidal environments.
• However, the biogenicity of these is contentious.

8. PROTEROZOIC STROMATOLITES
• In the Palaeoproterozoic and Mesoproterozoic, there
was an abundance of stromatolites with conical
laminae (Conophyton), characteristic of quiet subtidal
environments.
• There was a decline in the abundance and diversity of
all stromatolites about 600-700 Ma.
• Neoproterozoic fall in stromatolite morpho typic
diversity coincided with metazoan evolution, but
inception of decline prior to the appearance of
metazoans implicates reduction in seawater carbonate
saturation state as the major influence.
Conophyton

9. • Progressive reduction in saturation state leads
to the reduction of stromatolites and mediated
a long-term trend from sparry crust to micritic
carbonate sediments.
• This transition led to Neoproterozoic
development of calcimicrobial thrombolites.
• It has been recognized that thrombolites
appeared in the Neoproterozoic, and possibly
about 1.9 Ga in the Palaeoproterozoic.
Calcimicrobial thrombolites
Lake Clifton Thrombolites

10. PHANEROZOIC STROMATOLITES
• The decline of stromatolite abundance was observed in the
Phanerozoic.
• Stromatolites are common in the late Cambrian-early
Ordovician and late Devonian-early Mississippian, and scarce
during the Cenozoic.
• Fischer suggested that decline since the Ordovician could
reflect both reduction in carbonate saturation and competition
by eukaryotes.
• Stromatolites near the Permian-Triassic boundary are
uncommon; however, examples have been reported from
northern Italy, Iran, Oman, northern Hungary, southern Turkey,
South China and India.

11. • Stromatolites just after the end-Permian extinction are exceptionally well
developed in the Chong yang area of Hubei Province, South China.
• Modern stromatolites exist in extreme environments containing hypersaline
water, high alkalinity, and high or low temperatures zones.
• Such places exclude grazing snails and other animals which consume the
cyanobacteria.
• Recent formations of stromatolites are noted in Shark Bay (Australia) as well
as throughout Western Australia, the Bahamas, the Indian Ocean, various
places in the USA (such as in Yellowstone National Park), Laguna Salgada
(Brazil), the Mexican Desert, Glacier National Park (Montana and Canada),
and the Solar Lake in Sinai, which is heliothermally heated and contains
hypersaline water.

12. INDIAN STROMATOLITES
• In India, most of the stromatolites are reported from
Precambrian rocks. The Precambrian stromatolites are
recorded mainly from peninsular India and a few from the
Himalayas.
• Phanerozoic stromatolites, which are few in number, are
restricted to the Himalayan region.
• Kumar has divided stromatolites of India into two groups:
Stromatolites of the peninsular region lying in the
south of the Indo-Gangetic Alluvium
Stromatolites of the extra peninsular India lying in the
north of Indo-Gangetic Alluvium

13. EXTRA PENINSULAR REGION
• In the extra-peninsular region (i.e., Himalayan region), stromatolites have been recorded
from the sedimentary successions of the Lesser Himalaya.
• Stromatolites reported from different areas of the Himalayan region range from
Neoproterozoic to Devonian in age.
• In this region stromatolites have been reported from the Jammu Limestone, Sirban
Limestone, Raisi Limestone (Jammu and Kashmir); Shali Formation (Nahan Dist.,
Himachal Pradesh); Larji Formation (Larji Town, Himachal Pradesh); Simla Group; Tunda
Pathar Limestone 20 (Haryana); Lameri Formation (Garhwal Group); Blaini Formation
(Kumaon and Himachal Himalaya); Krol Formation; Tal Formation; Buxa Group (eastern
Nepal to Arunachal Pradesh); Matuka Formation (southern Tuensang dist., Nagaland).

14. PENINSULAR STROMATOLITES
• Stromatolites reported from different areas of the peninsular region range
from Archean to Ediacaran period
• In this region, reported stromatolites include those from the Iron Ore
Formation, Kaladgi Group, Cuddapah Supergroup, Delhi Supergroup,
Aravalli Group, Vindhyan Supergroup, Marwar Supergroup, Kurnool
Group.

15. THREATS TO STROMATOLITES
• Hamelin Pool is perfect for Stromatolites because it’s
hypersaline. Sea grass forms a ‘barrier’ between Hamelin
Pool and the rest of the ocean, preventing ocean
circulation, which would dilute the super-salty water.
• But sea grass meadows are being damaged by the runoff
caused by floods and extreme temperature events.
• Climate change is likely to lead to more frequent tropical
storms and more frequent flooding events in the area,
threatening the Stromatolites of Hamelin Pool.

16. • Human interference is another threat.
• To protect the delicate structures, visitors are restricted to the boardwalk. From here they
may be underwhelmed:
• Stromatolites look a little like cow pats from that vista.

17. REFERENCES
 Duda, J-P.; Van Kranendonk, M.J.; Thiel, V.; Ionescu, D.; Strauss, H.; Schäfer, N.; Reitner, J.
(2016).
 Sheehan, P.M.; Harris, M.T. (2004). "Microbialite resurgence after the Late Ordovician
extinction". Nature. 430 (6995): 75–78.
 PRECAMRIAN BACKGROUND AND PHANEROZOIC HISTORY OF STROMATOLITIC
COMMUNITIES AN OVERVIEW, Tome 96 -1973- Fascicules 111(pg:590-592), (607-614)
 Chandrashekara Gowda, M.J and Govinda Rajulu, B.V (1980) Stromatolites of the Kaladgi Basin
and their significance in paleoenvironmental studied J.G.S.I. Miscellaneous Pubn.No.44, Pp.220-
239