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mathematician...
Posted: Mon Jul 14, 2008 8:52 pm
Guest
About age of the Bulawayan stromatolite Bul-7 (= P.P.R.G. 253 Scopf’s
collection number).

I found a reference which gave the recent Lithological map of the Bubi
greenstone belt and
also formations from in the Bubi greenstone belt of Zimbabwe (near
Huntsman quarries):

Explanations of the Lithological map (Figure 2.3, and pages 13-15 of
the reference) :

c: Post Archean cover
F: Felsite and quartz porphyry
D: Dolerite
H: Gabro
G: Massive granitoids
S: Serpentinite and talc schist
yi: Banded iron formation
yl: Crystalline limestone

Shamvaian Group (x and xc):

x: Ndustshana Formation (greywacke and arkose)
xc: Ndutshana Formation (conglomerate)

Upper Bulawayan Group (y14-y11, from top to bottom):

y14: Dagmar Formation
y13: Eanovean Formation
y12: Dollar Block Formation
y11: Courtleigh Volcanic Formation

Middle Bulawayan Group (New name !!! old name for this was Upper
Bulawayan Group)
(y10a-y4, from top to bottom):

y10a: Lonely Mine Formation (sedimentary unit)
y10: Lonely Mine Formation (volcanic unit)
y9: Esinangeni Formation
y8: Ventnor Formation
y7a: Mbembesi River Formation (volcanoclastic unit)
y7: Mbembesi River Formation (volcanic unit)
y6: Zwangendaba Formation
y5: Sweetwater Formation
y4: Inyati Formation

Lower Bulawayan Group (y3-y1, from top to bottom):

y3: Bubi Source Formation
y2: Goodwood Formation
y1: Kenilworth Formation

Base:

Gm: Migmatics and gneissic granitoids.

Q1. I need to know what of these above formations fits in the Huntsman
quarries area
when the Bulawayan stromatolite sample Bul-7 was collected by Dr.
Keith Kvenvolden
in the year 1968 ?

Q2. I need also to know exact ages with error limits and sample code
names that in what
age limits Bul-7 stromatolite sample suits ?

Q3. I need to know the age limit of direct estimation from the correct
formation where the
stromatolite sample Bul-7 belongs, if possible ?

Reference:

Mhlanga Gilbert, 2002.
Data driven predictive modelling for Archean lode gold potential, Bubi
greentone belt,
south west Zimbabwe.
Master of Science Thesis.
International Institute for Geo-information Science and Earth
Observation.
Enschede, The Netherlands. 108 numbered pages (126 pages as pdf-file).
Pages 13-15.

(International Institute for Geo-information Science and
Earth Observation. In partial fulfilment of the requirements for the
degree in Master
of Science in Mineral Resources Exploration and Evaluation. Thesis
advisors:
Dr. E.M. Carranza and Prof. M. Hale. Thesis examiners: Prof. M. Hale
(Chairman), Dr. A.B. Westerhof (Member), Dr. S. Barrit (Member), Dr.
H. de Brooder (External Examiner), I.v.A.U. Utrecht).

This reference is available in the net and it can be found with aid of
the search machine "scholar.google.com"
with the search words: "Middle Bulawayan Group"

And directly from the internet address:

http://www.itc.nl/library/Papers/msc_2002/ereg/mhlanga.pdf



Best Regards,

Hannu Poropudas
Vesaisentie 9E,
90900 Kiiminki
Finland
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mathematician...
Posted: Fri Aug 01, 2008 10:22 pm
Guest
On Jul 15, 9:52 am, mathematician <hapor... at (no spam) luukku.com> wrote:
Quote:
About age of the Bulawayan stromatolite Bul-7 (= P.P.R.G. 253 Scopf’s
collection number).

I found a reference which gave the recent Lithological map of the Bubi
greenstone belt and
also formations from in the Bubi greenstone belt of Zimbabwe (near
Huntsman quarries):

Explanations of the Lithological map (Figure 2.3, and pages 13-15 of
the reference) :

c: Post Archean cover
F: Felsite and quartz porphyry
D: Dolerite
H: Gabro
G: Massive granitoids
S: Serpentinite and talc schist
yi: Banded iron formation
yl: Crystalline limestone

Shamvaian Group (x and xc):

x: Ndustshana Formation (greywacke and arkose)
xc: Ndutshana Formation (conglomerate)

Upper Bulawayan Group (y14-y11, from top to bottom):

y14: Dagmar Formation
y13: Eanovean Formation
y12: Dollar Block Formation
y11: Courtleigh Volcanic Formation

Middle Bulawayan Group (New name !!! old name for this was Upper
Bulawayan Group)
(y10a-y4, from top to bottom):

y10a: Lonely Mine Formation (sedimentary unit)
y10: Lonely Mine Formation (volcanic unit)
y9: Esinangeni Formation
y8: Ventnor Formation
y7a: Mbembesi River Formation (volcanoclastic unit)
y7: Mbembesi River Formation (volcanic unit)
y6: Zwangendaba Formation
y5: Sweetwater Formation
y4: Inyati Formation

Lower Bulawayan Group (y3-y1, from top to bottom):

y3: Bubi Source Formation
y2: Goodwood Formation
y1: Kenilworth Formation

Base:

Gm: Migmatics and gneissic granitoids.

Q1. I need to know what of these above formations fits in the Huntsman
quarries area
when the Bulawayan stromatolite sample Bul-7 was collected by Dr.
Keith Kvenvolden
in the year 1968 ?

Q2. I need also to know exact ages with error limits and sample code
names that in what
age limits Bul-7 stromatolite sample suits ?

Q3. I need to know the age limit of direct estimation from the correct
formation where the
stromatolite sample Bul-7 belongs, if possible ?

Reference:

Mhlanga Gilbert, 2002.
Data driven predictive modelling for Archean lode gold potential, Bubi
greentone belt,
south west Zimbabwe.
Master of Science Thesis.
International Institute for Geo-information Science and Earth
Observation.
Enschede, The Netherlands. 108 numbered pages (126 pages as pdf-file).
Pages 13-15.

(International Institute for Geo-information Science and
Earth Observation. In partial fulfilment of the requirements for the
degree in Master
of Science in Mineral Resources Exploration and Evaluation. Thesis
advisors:
Dr. E.M. Carranza and Prof. M. Hale. Thesis examiners: Prof. M. Hale
(Chairman), Dr. A.B. Westerhof (Member), Dr. S. Barrit (Member), Dr.
H. de Brooder (External Examiner), I.v.A.U. Utrecht).

This reference is available in the net and it can be found with aid of
the search machine "scholar.google.com"
with the search words: "Middle Bulawayan Group"

And directly from the internet address:

http://www.itc.nl/library/Papers/msc_2002/ereg/mhlanga.pdf

Best Regards,

Hannu Poropudas
Vesaisentie 9E,
90900 Kiiminki
Finland

My main problem which confuse me
are two writings (I. and II.):

I.
Bond G, Wilson J.F., Winnall N.J. 1973.
Age of the Huntsman Limestone (Bulawayan Stromatolites).
Nature, vol. 244, August 3, 1973, p. 275-276.
Page 275.

Dr. N.J.Winnall et al, who had made very detailed mapping
around the Huntsman quarries, said in this paper
that the stromatolitic limestone is interbedded in
normal sequence with typical Bulawayan rock types.
The succession in descending order is:

Greenstone
(dolerite sill)
Greenstone
Upper limestone
Banded ironstone
Lower limestone (with stromatolites)
Quartz sericite schist

The field relations are shown in Fig. 1.

(Text below this figure):

1.Dolerite
2.Greenstone
3.Upper limestone and banded ironstone
4.Quartz sercite schist
5.Lower limestone and banded ironstone
6.Quartz sericite schist

(1. = Intrusive)
(3.-6. = Zwankendaba Member)
(2.-6. = Lower Formation)
(2.-6. = Bulawayan Group).

II.
Wilson J.F., Bickle M.J., Hawkesworth C.J., Martin A., 1978.
Granite-greenstone terrains of the Rhodesian Archean craton.
Nature, vol. 271. 5 January 1978. p. 23-27. Page 25.

"J.F.W.'s correlations across greenstone belts also allow the
rationalization of the known occurences of
Rhodesian Archean stromatolites which now number five
(Fig. 1). All of these occur in the Upper Greenstones. Two occur in
limestones of the basal
formation below the thick tholeiitic pile; one at
Belingwe, and one at Redchiff south of Que Que
(C.A.Castelin, personal communication). Three occur
in limestones above the thick tholeiitic pile; one at
Belingwe, one south-east of Redcliff (C.A.Castelin, personal
communication)
and one the Huntsman limestone stromatolites of Macgregor,
some 60 km north of Bulawayo."

My most important question is now that does the
stromatolite sample Bul-7 (=P.P.R.G. 253, J.W. Schopf's collection
number)
(collected from tailings of pile of Huntsman
quarries by Dr. Keith Kvenvolden in the year
1968) belong in the Lower limestone
(= 5.Lower limestone and banded ironstone)
or does it belong in the Upper limestone
(= 3.Upper limestone and banded ironstone) ?

If it belongs into the Lower limestone then I have
age estimate of Bul-7 from the Belingwe Greenstone
Belt only:

Younger or equal than 2904 +- 9 Ma (Hokonui Formation, ZIM-number from
Wilson J.F. et al 1995)
Older or equal than 2831 +- 6 Ma (Koodoovale Formation, ZIM-number
from Wilson J.F. et al 1995)).

If it belongs into the Upper limestone then I have
age estimate of Bul-7 from the belingwe Greenstone Belt:

Younger or equal than 2706 +- 49 Ma (Manjeri Formation, Hofmann A et
al 2004, Chapter 15)
Older or equal than 2601 +- 49 Ma (Cheshire Formation, Hofmann A. et
al 2004, Chapter 15).

And from Harare area (Harare-Shamva greenstone sequence ?):

Younger or equal than 2715 +- 15 Ma
(ZIM-74, Iron Mask Formation)
Older or equal than 2672 +- 12 Ma
(ZIM-29, Harare-Shamva greenstone sequence,
"Black Cat porophyry").

Best Regards,

Hannu Poropudas
Vesaisentie 9E
90900 Kiiminki
Finland

email:
haporopu
at (no spam)
oulu.fi

or

hanporop
at (no spam)
luukku.com
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