Mapping MSA Deposits: Regional Geological Investigation of Upper Chari Member Sediments in the Ileret Region, East Turkana, Kenya Shannon Warren , Michael Ziegler , Silindokule Mavuso , Tamara Dogandzic , Kathryn L. Ranhorn , 1 4 David R. Braun , J.W.K. Harris 1
1
2
3
1
Center for the Advanced Study of Human Paleobiology, Department of Anthropology, George Washington University, Washington D.C., USA, 2 Evolutionary Studies Institute, University of the Witswatersrand, Johannesburg, South Africa, 3Department of Human Evolution, Max Planck Institute for Evolutionary Anthropology, Leipzig, Germany, 4National Museums of Kenya, Nairobi, Kenya 1
Ileret Region, East Turkana, Kenya 40 E
OMO KIBISH LAKE TURKANA
ILERET
ETHIOPIA
LAKE TURKANA
SOUTH SUDAN
O
ILERET
2ON
UGANDA
KF Fm.
2ON
SOMALIA
KOOBI FORA
KENYA
km
BARINGO
0O
0O
MT. KENYA
NAKURU
LAKE VICTORIA
N
NAIROBI
AFRICA 10OWO
2S
0O
10OE
20OE
30OE
40OE
50OE
30ON
10ON
INDIAN OCEAN
10ON
10OS
10OS
20OS
20OS
30 S
30 S
O
O
10OW
0O
10 E O
20 E O
30 E O
40 E O
0
TANZANIA 40OE
(37N 194423, 475487)
260
Area 6a (south)
(37N 194235, 51786)
240
(37N 194655, 475064)
220
Sm
220
220
Sm Sm
150
Chari
km
WGS 1984 WARREN (2017)
50 E O
•The Rift Valley of east Africa has exposed Middle-Late Pleistocene sediments, providing Middle Stone Age (MSA) archaeological sites, including Omo Kibish, Ethiopia and the Baringo Formation of central Kenya. •The Turkana Basin of northern Kenya lacks documented in situ MSA sedimentary units. -Archaeological fieldwork in the Ileret region noted localized MSA sites3, but a sedimentological survey of MSA units across space has yet to be conducted. -A major unconformity2 was identified in the Upper Chari (1.34 Ma - 10Ka) Member sediments of the Koobi Fora Formation (KF Fm.) in the Ileret region, leaving associated sediments undocumented.
Okote KBS Burgi Tulu Bor Lokochot Moiti
200
200
200
180
180
180
160
160 140
140
120
120
100
60 Sl Sm Sm Sl Sm
40
youngest
Lonyumun
20
oldest MEMBERS (not to scale)
Cm Fm, Sl Sm Fm, Sl
80
80
0 C
f
m
F
Carbonate Concretion Bivalve Gastropod
c
f
S
m
120
120
100
100
80
80 Sm
60
40
Sm
40
Sm
40
20
Fm Sm
20
Sm Fm
20
m
F
c
f
S
m
c
LITHOLOGIES LEGEND Erosional Contact
Abrupt Contact
Upward Fining Sequence
Sm
MSA Artifact
Gradational Contact
GEOLOGICAL MAP OF THE ILERET REGION WITH OCCURENCES OF SSM
0
N
C
f
m
F
c
f
S
m
•Further geoarchaeological survey will enhance understanding the context of MSA sedimentary package, SSM, as well as archaeological excavation to confirm Middle Pleistocene sediments.
Sm, Fm, Sl
Sm
0
c
•The Guomde Fm.1 and SSM are lithologically similar, but further survey of SSM is needed to confirm equality.
Cm Sm Cl Sm
140
60
f
Sm
160
Sl
C
Upward Coarsening Sequence
Sm
60
0
c
180
140
Fm
200
Sm
160
100
Sm
•MSA sedimentary units exist in the Ileret region of the KF Fm. -The depositional environment gives possible insight to the paleogeographical environment during the MSA. -Pending Ar/Ar analysis of an underlying documented tuff will give a maximum age to MSA artifacts of future excavations. -Geological map, lithologies, and SSM identification provide ideal locations for future MSA excavation sites.
Area 6a (north)
Area 6a (south)
(37N 196319, 469055)
GALANA BOI FM.
MOMBOSA
0O
KENYA
0O
Area 7
UNDOCUMENTED SEDIMENTS
20ON
20ON
•Correlation of SSM across four locations: -Bioclasts, a defining feature, is stratigraphically located in upper units of SSM. -A mudstone unit underlies upward coarsening aranaceous beds. •Area 6a represents a large area of exposed SSM, including area 7.
CORRELATION OF SSM STRATIGRAPHIC SECTIONS
2OS
KOOBI FORA FORMATION
30ON
10
0
•An MSA sedimentary package, named SSM, was discovered in the Upper Chari. -lithologically distinct; named for principal founders SW, SM, and MZ -in situ artifacts -unconformably (angular) deposited -underlies Galana Boi (10 Ka - present) Fm. -unconformably overlies a documented tuff, geochemically correlated (table 1)
Centimeters
36 E O
Conclusion
Results
Introduction
C
f
m
F
c
f
S
m
c
LITHOFACIES LEGEND Massive Sands Laminated Sands
Coarse Sands Mudstone
Sm - sands, massive Fm - silts, massive Sl - sands, laminated Cm - clays, massive
Acknowledgments We thank the Koobi Fora Field School and NSF-IRES grants 1358178 and 1358200 for funding and logistical support. The Koobi Fora Middle Stone Age project was supported by Fulbright-Hays, the Wenner Gren Foundation, and the Leakey Foundation (PI: KR).
Table 1. Documented Tuff geochemical signals in Areas 6a and 7
Area 5 Area 5 f
•Find MSA sedimentary units -locate, name, map and stratigraphically correlate •Create a geological map of the Ileret region -survey Upper Chari Member sediments of the KF Fm. --document lithologies and stratigraphic markers --measure and locate geological features using clinometer and GPS --collect samples of tuffs in the Upper Chari for XRF and Ar/Ar analysis
fA
Area 4
y
Area 6A
f
A
y
Galana Boi Fm. (Holocene)
Area 6a fS
fA
Area 7
B
0
,
BOWEN, BRUCE EUGENE, 1974. The geology of the Upper Cenozoic sediments in the East Rudolf embayment of the Lake Rudolf basin, Kenya. 70-76. 2 GATHOGO, N. PATRICK AND FRANCIS H. BROWN, 2006. Stratigraphy of the Koobi Fora Formation (Pliocene and Pleistocene) in the Ileret region of northern Kenya. Journal of African Earth Sciences 45, 369-390. 3 KELLY, ALLISON J. AND JOHN W. K. HARRIS, 1992. Recent Findings of Middle Stone Age Material from East Turkana. 38, 29-34.
SSM
x
5 km
Documented Tuff
SSM locality in area 7
Contact Information:
f
410 405
Area 7
N
References
1
Area 4
Elevation (masl)
Objectives and Methods
x
400 395 390 385 380 375
x
y
Cross section (x---y) of strategraphic interactions and SSM (yellow)
SW -
[email protected] MZ -
[email protected] SM -
[email protected] TD -
[email protected] KR -
[email protected] DRB
[email protected] JWKH- National Museums of Kenya
