Download Glacial geology of Bayan Har Shan, northeastern

Glacial geology of Bayan Har Shan, northeastern Tibetan Plateau
Jakob Heyman
Abstract
The paleoglaciology of the Tibetan Plateau is still largely unexplored, despite its importance for
regional and global climate reconstructions. In this thesis a comprehensive glacial geological record
is presented from an extensive part of the northeastern Tibetan Plateau centred on the Bayan Har
Shan. Glacial reconstructions for this region range from restricted mountain glaciers through the
intermediate-size regional-scale Huang He ice sheet to a plateau-scale Tibetan ice sheet. To provide
a robust basis for glacial reconstructions, this thesis provides conclusions based on two principle
methods, remote sensing and field studies. The remote sensing of a 90 m resolution digital elevation
model and 15- and 30 m resolution satellite imagery renders a detailed data set with complete
spatial coverage of large- and medium-scale glacial landforms, and large-scale plateau
geomorphology. Observations from fieldwork campaigns add detailed point information for the
distribution of glacial deposits. Geomorphological glacial traces such as glacial valleys, glacial
lineations, marginal moraines, meltwater channels, and hummocky terrain occur frequently in
elevated mountain areas, indicating former alpine-style glaciations. Glacial deposits in the form of
till, erratic boulders, and glaciofluvial sediments are common in areas with mapped glacial
landforms, but also beyond, in areas lacking large-scale glacial landforms. For extensive plateau
areas in-between formerly glaciated mountain blocks, there is a striking absence of glacial
landforms and sediments, indicating that these areas, perhaps, never were ice covered. Interestingly,
glacial deposits occur further away from the mountain blocks than the large- and medium-scale
glacial landforms, indicating insignificant erosion beneath the maximum ice covers close to their
margins.
The large-scale geomorphology of the northeastern Tibetan Plateau is characterised by a low-relief
plateau surface with glacial valleys in elevated mountain blocks and marginal steep V-shaped
valleys. This geographical distribution indicates a dominance of glacial erosion in the elevated
mountain areas and a dominance of fluvial erosion along the steep plateau margins, dissecting a
relict plateau surface. The outline of the relict plateau surface mimics the proposed outline of the
Huang He ice sheet, suggesting that the inferred ice sheet may represent a misinterpreted relict
surface with scattered glacial traces.
In conclusion, the glacial geology examined in the Bayan Har Shan region is consistent with paleoglaciers of varying extent restricted to elevated mountain areas. Even though extensive icefields/ice
caps were centred on discrete mountain areas, there is no indication that these ice masses merged
but rather that they were separated from each other by unglaciated plateau areas. The presented
glacial geological record will be used in further studies towards a robust paleoglaciological
reconstruction for the northeastern Tibetan Plateau.
Cover photo: Erratic granite boulder north of central Bayan Har Shan with a U-shaped cross-section
of the parent glacial valley in the background.
1
This thesis consists of a summary, three papers and a map:
Paper I, including a map on attached CD (P I)
Heyman J, Hättestrand C, Stroeven AP. in press: Glacial geomorphology of the Bayan Har sector of
the NE Tibetan plateau. Journal of Maps.
Paper II (P II)
Stroeven AP, Hättestrand C, Heyman J, Harbor J, Li YK, Zhou LP, Caffee MW, Alexanderson H,
Kleman J, Ma HZ, Liu GN. in press: Landscape analysis of the Huang He headwaters, NE Tibetan
Plateau – patterns of glacial and fluvial erosion. Geomorphology.
Paper III (P III)
Heyman J, Stroeven AP, Alexanderson H, Hättestrand C, Li YK, Harbor J, Caffee MW, Zhou LP,
Veres D, Liu F, Machiedo M. manuscript: Field data for the glacial extent in Bayan Har Shan, NE
Tibetan Plateau – paleo-glaciers restricted to separate mountain blocks.
For P I, I performed the mapping, building on initial mapping by Clas Hättestrand and Arjen
Stroeven, and I wrote most of the text and drew the figures, with significant input from my coauthors. For P II, Clas Hättestrand and Arjen Stroeven conducted the mapping and wrote most of
the text. I contributed significantly with data analysis, writing and illustrations. For P III, I
supervised and performed most of the data collection, and I was responsible for data analysis,
writing and illustrations, with significant input from my co-authors.
2
Introduction
areas, as exemplified by the Li et al. (1991) glacial
reconstruction for the Tibetan Plateau (cf. Fig. 1).
However, because there is an absence of glacial
geological data for extensive parts of the plateau (c.f. P
I), presented plateau-wide reconstructions are at best
crude estimates. There is, consequently, a frequently
broadcasted need for further detailed studies of the
Tibetan glacial geology (e.g. Osmaston 1989;
Derbyshire et al. 1991; Rutter 1995; Zheng and Rutter
1998; Benn and Owen 2002; Lehmkuhl and Owen
2005). One of the more intriguing corners of the
Tibetan Plateau in this regard is the Bayan Har Shan
(Shan means mountain) with the source area of Huang
He (Yellow River) as it has been credited with variable
paleo-ice extents. This is where the work contained in
this thesis has its focus (Fig. 1).
The Tibetan Plateau is a topographic feature of extraordinary dimension and, consequently, it has an
important impact on regional and global climates. It
has been proposed, for example, that the uplift of the
plateau, in response to the Indian-Asian continental
collision, caused the Asian monsoon dynamics and a
global cooling trend which triggered the onsets of
Quaternary climate oscillations (e.g. Molnar and
England 1990; Raymo and Ruddiman 1992; An et al.
2001). However, the glacial history of the Tibetan
Plateau, in spite of its proposed significance for climate
change, is a research field still in its infancy. While
research on Laurentide and Fennoscandian glaciations
have at least partly attained a stage of detailed analysis,
research on the Tibetan Plateau glacial history still
deals with the basic questions of extent and timing.
The upper reaches of Huang He receive their water
from the northern slopes of Bayan Har Shan. In this
area, a regional ice sheet has been proposed to have
existed – the Huang He ice sheet. The Huang He ice
sheet, with a peculiar triangular outline and of
Icelandic size, was first described in the
palaeoglaciological map by Li et al. (1991) as an
“Estimated extent of paleoglaciation” (Fig. 1). This
map unit contrasts with the apparently somewhat more
certain “Extent of paleoglaciation” which marks all
other formerly glaciated areas, including a more
restricted glacier extent around Bayan Har Shan that
falls within the Huang He ice sheet area (Fig. 1). Based
mainly on field investigations, Zhou and Li (1998)
presented a glacial reconstruction comprising four
glacial stages in the Huang He ice sheet area. Two
stages were identified where glaciers were restricted to
the highest mountain areas and these were proposed to
correspond to the early and late last glaciation. These
stages were proposed to have been predated by a more
extensive marine oxygen isotope stage (MIS) 6 glacial
stage and a most extensive Huang He ice sheet MIS 12
glacial stage. However, the physical basis for this
reconstruction is meagre, with only scattered
observations of glacial landforms and deposits and an
absence of chronological control. Alternative
interpretations for the glacial history of the Bayan Har
Shan exist (Lehmkuhl et al. 1998; Zheng and Rutter
1998), and these favour restricted glaciations based on
an absence of unambiguous glacial traces and they
question, therefore, the existence of regional-scale and
plateau-scale ice sheets in this area.
Likely triggered by the suggestion of a plateau-scale
ice sheet (Kuhle 1985, 2004 and references there-in),
the last 20 years have seen a significant increase in
research on the Tibetan Plateau glacial history. Kuhle
(2004 and references there-in), based on inferred
glacial geological traces and reconstructed Equilibrium
Line Altitudes (ELA), has suggested that almost the
entire plateau was covered by an ice sheet of
dimensions similar to the Greenland ice sheet during
the global Last Glacial Maximum (LGM). This idea
has been subjected to intense disapproval (e.g.
Derbyshire et al. 1991; Rutter 1995; Zheng and Rutter
1998; Owen et al., 2005; Lehmkuhl and Owen 2005)
and a large amount of data strongly indicates that at
least during the last few hundred thousand years there
has been no plateau-scale ice sheet on the Tibetan
Plateau. Two circumstances stand out as particularly
problematic for a plateau-scale LGM ice sheet concept.
First, there is a remarkable absence of glacial
indicators (such as glacial lineations, eskers, ribbed
moraines, marginal moraines, till, and erratic boulders)
for extensive areas of the plateau outside mountain
areas. Second, terrestrial cosmogenic nuclide exposure
dating and optically stimulated luminescence dating
techniques, which are effective chronological tools for
glacial geologists (e.g. Gosse and Philips 2001;
Bierman 2007), have provided LGM ages from
restricted mountain areas and a large number of ages
on glacial landforms and deposits older than the late
last glaciation (e.g., Owen et al. 2005). To summarize,
the concept of a plateau-scale Tibetan ice sheet during
the LGM is generally rejected based on available
dating evidence, and the presence of a unified plateauscale ice sheet at any other time before the LGM faces
the current uphill-struggle of an absence of landforms
and deposits in its support.
The Bayan Har Shan investigation area can be
described as a low-relief plateau at c. 4300 metres
above sea level (m a.s.l.) with elevated mountain areas
generally reaching up to 1000 m higher, and including
the significantly higher Anyemaqen Shan (6282 m
a.s.l.) in its northeastern corner. Tributaries of Chang
Jiang (Yangtze River), the major river bordering the
study area towards the southwest, and Huang He in the
east, are cutting deep V-shaped valleys into the plateau
The paleoglaciology of the Tibetan Plateau is
dominantly thought of as a collection of paleo-glaciers
of varying extent but restricted to elevated mountain
3
Fig. 1. The Tibetan Plateau with the study area in the northeastern corner and the interpretation of the Quaternary
glacial distribution map (Li et al. 1991).
area. Mountain ranges are generally trending along
fault lines in a NW-SE orientation.
Remote sensing of the entire study area has been
performed using two data sets: the Shuttle Radar
Topography Mission (SRTM) 90 m resolution Digital
Elevation Model (DEM) (Jarvis et al. 2006), and
Landsat ETM+ 15 m resolution satellite imagery
(acquired from Global Land Cover Facility,
http://www.landcover.org, accessed 17 January 2008).
For 3D visualization, Google EarthTM software has
been frequently employed. The remote sensing
methodology, by virtue of its complete coverage over
extensive areas, provides a powerful tool to yield
spatially-continuous records of glacial landforms over
large areas and based on uniform information. Its
predominant limitation is the spatial resolution of the
data, where small-scale features, such as small moraine
ridges and roche moutonnées, may fall outside the
lower limit of recognition.
Clearly, the paleoglaciology of the northeastern
Tibetan plateau is not satisfactory researched, with
several crucial questions still unresolved. In my PhD
project I am aiming to provide a robust
paleoglaciological reconstruction of the Bayan Har
Shan area based on mapping, field evidence and
numerical
dating
techniques.
Ideally,
a
paleoglaciological reconstruction would provide a
temporally continuous glacial development for the
study area, including details on glacier outline,
topography, thermal regime, and ice dynamics (cf.
Kleman et al. 2002; Napieralski et al., 2007). However,
due to the complexity and difficulties of the glacial
inversion problem (Kleman et al. 2006),
paleoglaciological reconstructions are more typically
composed of two main parts; a spatial dimension
giving the glacier outlines, and a temporal dimension
giving the chronology, presenting time slice images of
former glacial extents (e.g. Boulton and Clark 1990;
Kleman et al. 1997; Svendsen et al. 2004; Ehlers and
Gibbard 2007). In this classical way, my thesis deals
with the spatial dimension of the northeastern Tibetan
Plateau paleoglaciology. In particular, it presents the
input data (in P I, P II, and P III) for a robust
reconstruction of the former extent of glaciers.
Three field campaigns were carried out during 2005,
2006 and 2007. We have investigated landforms and
sediments with the aim to either associate features with
the former presence of a glacier or to exclude glacial
processes as the formative agent. The field campaigns
yielded detailed information on glacial geology,
however, somewhat curtailed by its restricted spatial
coverage (along roads and walking tracks).
Results
Methodology
The results of this thesis are graphically presented in
Figure 2, displaying mapped glacial geomorphology
(from P I) from remote sensing and the distribution of
observed glacial deposits (from P III) from fieldwork,
and are summarized below.
Two general methods have been used to map the extent
of former glaciers: remote sensing and field
investigations.
4
Fig. 2. Glacial geology of Bayan Har Shan.
P I:
Heyman J, Hättestrand C, Stroeven AP. in press:
Glacial geomorphology of the Bayan Har sector of the
NE Tibetan plateau. Journal of Maps.
P II:
Stroeven AP, Hättestrand C, Heyman J, Harbor J, Li
YK, Zhou LP, Caffee MW, Alexanderson H, Kleman
J, Ma HZ, Liu GN. in press: Landscape analysis of the
Huang He headwaters, NE Tibetan Plateau – patterns
of glacial and fluvial erosion. Geomorphology.
We here present the distribution of glacial landforms in
the Bayan Har Shan study area, including glacial
valleys and troughs, glacial lineations, marginal
moraines and moraine remnants, meltwater channels,
and hummocky terrain. However, there is a notable
absence of landform assemblages that are typical for
ice sheets elsewhere on Earth such as glacial lineation
swarms, ribbed moraines, and eskers. Mapping
procedures using remote sensing techniques are
described and also include definitions of the mapped
landforms. The glacial landforms are concentrated in
and around well-defined elevated mountain areas,
while there is a remarkable absence of glacial
landforms for extensive lower-lying plateau areas. In
summary, evidence displayed on the map that is part of
this publication offers support for former alpine style
glaciation but renders no support to the existence of
larger-scale ice sheet glaciation.
In this paper we present an analysis of the large-scale
geomorphology of the Bayan Har Shan study area, and
the relative importance of glacial and fluvial erosion in
shaping the plateau area. Based on remote sensing, a
tripartite classification system was presented, glacial
landscapes (including U-shaped glacially eroded
valleys), relict upland surfaces, and fluvial landscapes
dominated by V-shaped valleys formed by fluvial
incision of tributaries to the Chang Jiang and Huang
He. In elevated mountain areas of the relict upland
surface, the glacial valleys are wider and deeper than
adjacent fluvial valleys, indicating that, integrated over
time, the glacial system has been more erosive than the
fluvial system. Along the plateau margin, however, this
relationship is reversed with dramatic fluvial
rejuvenation having consumed/consuming whatever
5
glacial morphologies existed. The outline of the relict
upland surface closely mimics the outline of the
proposed Huang He ice sheet. This circumstance could
indicate one of two options with conflicting glacial
implications: (1) The Huang He ice sheet was even
more extensive because parts of the glacial record are
being consumed by fluvial incision. (2) The proposed
regional ice sheet is based on a mis-interpretation of a
relict upland surface, whose outline is determined by
marginal fluvial incision, with scattered glacial traces.
In the absence of large-scale glacial landforms for
extensive areas within the study area, the preferred
interpretation is the latter of these.
beyond that mapped for glacial geomorphologies,
indicating an absence of large-scale glacial landforms
in areas of most extensive glaciation. In addition, new
data shows that previously proposed glacial deposits
located in lower-lying plateau areas were probably
formed by non-glacial processes. In summary, field
evidence support the presence of extensive ice masses
in the form of separate ice caps or icefields over
elevated mountain areas but it leaves no support to the
presence of any former ice sheet.
P III:
Heyman J, Stroeven AP, Alexanderson H, Hättestrand
C, Li YK, Harbor J, Caffee M, Zhou LP, Veres D, Liu
F, Machiedo M. Manuscript: Field data for the glacial
extent in Bayan Har Shan, NE Tibetan Plateau – paleoglaciers restricted to separate mountain blocks.
A preliminary and tentative reconstruction of the
maximum glacial extent permitted by the mapped
glacial geology (Fig. 2, P I, P II, P III) is presented in
Figure 3. The reconstruction encompasses all glacial
traces (Fig. 2) and includes a glacial altitude increase
towards the interior of the plateau (Li et al. 1991;
Lehmkuhl 1998; Benn and Owen 1998; P II). The
reconstructed maximum glacial extent covers 68.000
km2, representing an extensive glaciation of
approximately 50% of the 136.500 km2 study area. The
dominant ice mass was elongated in a NW-SE
orientation along Bayan Har Shan. It was, however,
significantly smaller than the proposed Huang He ice
sheet of estimated 95.500 km2 (Li et al. 1991) or
85.500 km2 (Zhou and Li 1998).
Glacial extent
In this paper we present field evidence for glacial
extent in the Bayan Har Shan and compare glacial
geological point observations to the pattern of
glaciation inferred from remote sensing data (P I, P II).
For the identification and mapping of glacial deposits
we relied on glacial indices such as the presence of
erratic boulders, of striated clasts, of diamictic
sediments, and of clasts of multiple lithologies. Similar
to the distribution of glacial geomorphology, glacial
deposits are centred on and around elevated mountain
areas. However, glacial deposits occur also in a zone
Fig. 3. A preliminary and tentative reconstruction for the maximum glacial extent based on the glacial geological
record (cf. Fig. 2).
6
Conclusions
represented an icefield or ice cap-type of glaciation.
Based on satellite data of the northeastern Tibetan
Plateau and field observations during three consecutive
years, the following conclusions can be drawn:
Outlook
The glacial geological record presented in this thesis is
an ample record of former glaciations on the
northeastern Tibetan Plateau. Still, to use this record
for a paleoglaciological reconstruction is not a simple
and straight-forward task. The glacial geological record
varies considerably between different areas, potentially
caused by varying glacial histories and glacier
dynamics, but also due to the spatial coverage of our
field studies. Generally, there is a great amount of
subjectivity when transforming a glacial geological
record into discrete glacial extents (e.g. Li et al. 1991;
Zhou and Li 1998; Fig. 3), leaving the field open for
speculative reconstructions of poor foundation. To get
around this problem, I intend to perform the
transformation of the glacial geology into glacial
extents using a clear methodology based on ELA
reconstructions. A four point procedure for this
transformation is outlined below:
• Glacial landforms occur frequently in elevated
mountain areas on the relict plateau surrounding the
Bayan Har Shan, indicating former glaciation
strongly controlled by altitude. Distinct sets of
marginal moraines and meltwater channels help
distinguishing between discrete glacial extents
ranging from cirque glaciers to extensive valley
glacier networks. There is an absence of glacial
landforms for lower-lying intervening plateau areas
and ice sheet landform assemblages characteristic
for northern Hemisphere mid-altitude ice sheets are
lacking altogether. Thus, glacial geomorphology
indicates only the former presence of alpine style
glaciations.
• Glacial deposits occur frequently in elevated
mountain areas, similar to the glacial landforms. In
addition, glacial deposits occur at lower elevations
some distance beyond the mapped glacial
geomorphology. This indicates that icefields which
extended beyond the area of visible glacial
geomorphology were apparently incapable of
significant glacial erosion, possibly because these
where short-lived events. In the lowest-lying plateau
areas, there is a striking absence of glacial deposits.
The observed distribution of glacial deposits
indicates that glaciations were controlled by altitude,
that the maximum glacial extent exceeds that
inferred from glacial geomorphological alone, and
that it offers no support for the presence of paleo-ice
sheet configurations.
1. Definition of the ELA pattern of the study area.
2. ELA reconstructions for a part of the study area
with well-defined ice marginal positions.
3. Reconstruction of ice marginal positions for the
entire study area employing inversion of the ELA
reconstruction (point 2) in combination with the
ELA pattern (point 1).
4. Extrapolation of the ice marginal outline between
the ice marginal locations given by point 3.
The timing of former glaciations in Bayan Har Shan is
still to be revealed. To constrain the glacial chronology
we are performing cosmogenic isotope exposure dating
as well as optically stimulated luminescence dating of
glacial deposits. We have collected a large number of
samples from an extensive area, and we intend to adopt
varying cosmogenic analysis techniques, such as dating
of boulder surfaces, sediment depth profiles and sets of
surface cobbles. In addition, cosmogenic exposure
dating of river sediment samples may provide a
measure of erosion rates which can confirm or disprove
the idea of a relict plateau surface being consumed by
fluvial incision (P II).
• The northeastern Tibetan Plateau is composed of a
low-relief relict plateau surface with elevated
mountain areas. The relict surface is being
consumed by fluvial incision of the Chang Jiang and
Huang He tributary rivers. The size and depth of
glacial valleys testify of glacial erosion surpassing
fluvial erosion in the elevated mountain areas of the
plateau surface when integrated over glacial time
spans. At the plateau margin this relationship is
reversed, with fluvial erosion eradicating whatever
glacial landforms may have existed. The outline of
the relict plateau surface broadly resembles the
outline of proposed Huang He ice sheet, indicating
that the triangular regional ice sheet may have come
about as a misinterpreted relict plateau surface with
scattered glacial traces.
Acknowledgements
First I want to thank my supervisors, Arjen Stroeven,
Clas Hättestrand and Helena Alexanderson, who have
guided me in a positive, helpful, inspiring and friendly
atmosphere. My principle supervisor Arjen has been a
fantastic support with very valuable comments on
• The glacial geology of the Bayan Har Shan indicates
that
the
northeastern
Tibetan
Plateau
paleoglaciology was restricted to elevated mountain
areas. In its most expansive outline it probably
7
various topics, enthusiasm over glacial issues and a
dinner-at-University company. Similarly, Clas and
Helena have been excellent co-supervisors always
ready to help with different issues. Clas was also to a
great extent involved in getting me into
paleoglaciological research, as he guided me in such a
good way during my undergraduate-degree project on
Swedish marginal moraines. All of my supervisors also
participated in the Bayan Har fieldwork of 2006, and
have given valuable comments for this summary. I am
looking forward to continuing working on this project
together with you!
courses, conferences and research visits, group
meetings and cosmogenic exposure dating (in progress)
has been provided by PRIME Lab, Purdue University,
by courtesy of Prof. Marc Caffee, VR/SIDA – Swedish
Research Links grant 348-2004-5684 to Arjen Stroeven
and the Royal Swedish Academy of Sciences (Margit
Althins
stipendiefond
and
Hierta-Retzius
stipendiefond), the Swedish Society for Anthropology
and Geography (Andréefonden and Vegafonden), Carl
Mannerfelts fond, A.E.W. Smitts stipendiestiftelse,
Ahlmanns fond, Peking University (SU/PKU
Academic Exchange Agreement), C.F. Liljevalch J:ors
resestipendium, and Gerard De Geers stiftelse to Jakob
Heyman.
This project has involved a large number of helpful
people who have contributed to this thesis in many
different ways. Zhou Liping, at Peking University, has
been helping out in a splendid way with the logistics of
my two fieldworks 2006 and 2007. Zhou Liping was
also an excellent host for my visit at Peking University
after the fieldwork of 2007, providing an open and
friendly atmosphere and giving me possibilities to
conduct research. Liu Gengnian introduced me to the
Tibetan Plateau in a very friendly and favourable way,
during some memorable days in August 2006 from
Geermu (Golmud) and across the plateau to Lhasa. Li
Yingkui, Jon Harbor and Marc Caffee have been
helping out with several issues, although for sure being
overwhelmed by other commitments, and they have
offered very nice company during several meetings and
in the field. Jon and Marc have also been extremely
helpful and hospitable during my stay at PRIME Lab,
Purdue University, for processing TCN samples. Johan
Kleman has added sharp analysis to the project in an
inspiring way, and he has also helped out with practical
details. During my two trips to China, two persons
have helped out in an extraordinary way, translating,
explaining, discussing and helping me with anything I
could ever imagine. Liu Feng during 2007 and Dong
Jianyi during 2006 have helped me in a way far
exceeding what could be expected, and for this I am
deeply thankful. In addition to Feng and Jianyi, I have
had very nice company during the fieldworks with
Martin Machiedo and Ma Luyi in 2006 and Daniel
Veres in 2007, making the sometimes harsh fieldworks
to very joyful and nice experiences. Göran Alm has
been a fantastic resource when it comes to DEM and
satellite imagery work. Åke Nagrelius at Stockholm
University and Li Yun at Peking University have been
very helpful in connection with my exchange visit to
Peking University.
References
An ZS, Kutzbach JE, Prell WL, Porter SC. 2001:
Evolution of Asian monsoons and phased uplift of the
Himalayan Tibetan plateau since late Miocene times.
Nature, 411, 62-66.
Benn DI, Owen LA. 1998: The role of the Indian
summer monsoon and the mid-latitude westerlies in
Himalayan glaciation: review and speculative
discussion. Journal of the Geological Society, London,
155, 353-363.
Benn DI, Owen LA. 2002: Himalayan glacial
sedimentary environments: a framework for
reconstructing and dating the former extent of glaciers
in high mountains. Quaternary International, 97-98, 325.
Bierman P. 2007: Cosmogenic glacial dating, 20 years
and counting. Geology, 35, 575-576.
Boulton GS, Clark CD. 1990: A highly mobile
Laurentide Ice Sheet revealed by satellite images of
glacial lineations. Nature, 346, 813-817.
Derbyshire E, Shi YF, Li JJ, Zheng BX, Li SJ, Wang
JT. 1991: Quaternary glaciation of Tibet: the
geological evidence. Quaternary Science Reviews, 10,
485-510.
Ehlers J, Gibbard PL. 2007. The extent and chronology
of Cenozoic Global Glaciation. Quaternary
International, 164-165, 6-20.
I also want to thank fellow PhD students and other staff
at the Department of Physical Geography and
Quaternary Geology for creating a very nice
atmosphere to work in. In particular, I want to thank
Tim Johnsen for bringing me twice to Jämtland for
fieldwork during the autumn 2005.
Gosse JC, Phillips FM. 2001: Terrestrial in situ
cosmogenic nuclides: theory and application.
Quaternary Science Reviews, 20, 1475-1560.
Jarvis A, Reuter HI, Nelson A, Guevara E. 2006: Holefilled seamless SRTM data V3. International Centre for
Tropical Agriculture (CIAT). Available from:
http://srtm.csi.cgiar.org [7 January 2008]
Funding for fieldwork, participation in far away PhD
8
Kleman J., Hättestrand C., Borgström I., Stroeven A.
1997: Fennoscandian palaeoglaciology reconstructed
using a glacial geological inversion model. Journal of
Glaciology, 43, 283-299.
Osmaston H. 1989: Problems of the Quaternary
geomorphology of the Xixabangma region in South
Tibet and Nepal. Zeitschrift für Geomorphologie N.F.
Supplementband, 76, 147-180.
Kleman J., Hättestrand C., Stroeven AP, Jansson KN,
De Angelis H, Borgström I. 2006: Reconstruction of
palaeo-ice sheets – inversion of their geomorphological
record. In Glacier Science and Environmental change,
Knight P (ed). Blackwell Publishing, Oxford, 192-198.
Owen LA, Finkel RC, Barnard PL, Ma HZ, Asahi K,
Caffee MW, Derbyshire E. 2005: Climatic and
topographic controls on the style and timing of Late
Quaternary glaciation throughout Tibet and the
Himalaya defined by 10Be cosmogenic radionuclide
surface exposure dating. Quaternary Science Reviews,
24, 1391-1411.
Kuhle M. 1985: Glaciation Research in the Himalayas:
A New Ice Age Theory. Universitas, 27, 281-294.
Raymo ME, Ruddiman WF. 1992: Tectonic forcing of
late Cenozoic climate.
Nature, 359, 117-122.
Kuhle M. 2004: The high glacial (last ice age and
LGM) ice cover in High and Central Asia. In
Quaternary Glaciations - Extent and Chronology, Part
III: South America, Asia, Africa, Australia, Antarctica,
Ehlers J, Gibbard PL (eds). Elsevier, Amsterdam, 175199.
Rutter N. 1995: Problematic ice sheets. Quaternary
International, 28, 19-37.
Svendsen JI, Alexanderson H, Astakhov VI, Demidov
I, Dowdeswell JA, Funder S, Gataullin V, Henriksen
M, Hjort C, Houmark-Nielsen M, Hubberten HW,
Ingólfsson Ó, Jakobsson M, Kjær KH, Larsen E,
Lokrantz H, Lunkka JP, Lysa A, Mangerud J,
Matiouchkov A, Murray A, Möller P, Niessen F,
Nikolskaya O, Polyak L, Saarnisto M, Siegert C,
Siegert MJ, Spielhagen RF, Stein R. 2004: Late
Quaternary ice sheet history of northern Eurasia.
Quaternary Science Reviews, 23, 1229-1271.
Lehmkuhl F. 1998: Extent and spatial distribution of
Pleistocene glaciations in eastern Tibet. Quaternary
International, 45/46, 123-134.
Lehmkuhl F, Owen LA. 2005: Late Quaternary
glaciation of Tibet and the bordering mountains: a
review. Boreas, 34, 87-100.
Lehmkuhl F, Owen LA, Derbyshire E. 1998: Late
Quaternary Glacial History of Northeast Tibet.
Quaternary Proceedings, 6, 121-142.
Zheng BX. 1989: Controversy Regarding the Existence
of a Large Ice Sheet on the Qinghai-Xizang (Tibetan)
Plateau during the Quaternary Period. Quaternary
Research, 32, 121-123.
Li BY, Li JJ, Cui ZJ, Zheng BX, Zhang QS, Wang FB,
Zhou SZ, Shi ZH, Jiao KQ, Kang JC. 1991:
Quaternary glacial distribution map of Qinghai-Xizang
(Tibet) plateau. Science Press, Beijing. (Map scale:
1:3.000.000)
Zheng BX, Rutter N. 1998: On the problem of
Quaternary glaciations, and the extent and patterns of
Pleistocene ice cover in the Qinghai-Xizang (Tibet)
plateau. Quaternary International, 45/46, 109-122.
Molnar P, England P. 1990: Late Cenozoic uplift of
mountain ranges and global climate change: Chicken
or egg?. Nature, 346, 29-34.
Zhou SZ, Li JJ. 1998: The sequence of Quaternary
glaciation in the Bayan Har mountains. Quaternary
International, 45/46, 135-142.
Napieralski J, Harbor J, Li YK. 2007: Glacial
geomorphology and geographic information systems.
Earth-Science Reviews, 85, 1-22.
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