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sional surfaces were used to define depositional
sequences and systems tracts.
We identified two main transgressive
cycles in the lower and middle-upper
Cenomanian separated by a major regression
at the early-middle Cenomanian
transition (sequence boundary Ce 3).
This regressive interval is characterized
by lagoonal low-stand deposits indicating
an overall sealevel fall of more than
30 m. Superimposed on the two main
transgressive cycles, there are 11 thirdorder
depositional sequences that correlate
to globally recognized sealevel fluctuations
and appear to be paced by long
eccentricity variations (400 Ka period).
Positive carbon isotope excursions in the
middle Cenomanian (96.0 Ma) and latest
Cenomanian (94.0 Ma) following
sealevel lowstands together with planktonic
foraminiferal and ammonite datums
provide a robust framework for
stratigraphic correlation. We suggest that
the onset of these excursions was triggered
by eccentricity minima during periods
of low variability in obliquity
(nodes), which probably coincided with
glacioeustatic lowstands.
2010010567
西 藏 日 喀 则 恰 布 林 地 区 晚 白 垩 世 和 新
生 代 相 关 碰 撞 砾 岩 的 孢 粉 地 层 及 其 古
环 境 发 育 的 意 义 = Palynological stratigraphy
of the Late Cretaceous and Cenozoic
collision-related conglomerates
at Qiabulin, Xigaze, Xizang (Tibet) and
its bearing on palaeoenvironmental development.
( 英 文 ). Li Jian-guo ;Guo
Zhen-yu; Batten D J;Cai Hua-wei;Zhang
Yi-yong;Li Jian-guo; Guo Zhen-yu;.
Journal of Asian Earth Sciences, 2010,
38(3-4): 86-95
The stratigraphy, age, depositional
environment and correlation of the collision-related
variegated sandstone and
conglomerate beds exposed along the
southern side of the Gangdise Mountains
to the north of the Yarlung Zangbo suture
in the Xigaze region, Xizang (Tibet)
have been much debated. Generally referred
to as the Dagzhuka Formation,
these beds of great thickness have, until
recently, not been reported to contain
any convincing fossils. Two distinctly
different palynological assemblages, indicating
Late Cretaceous and Oligocene–Early
Miocene ages respectively,
have now been recovered from
lithologically distinguishable units of the
sedimentary succession at Qiabulin to
the west of the town of Xigaze. This
means that instead of one stratigraphic
unit, as has been generally accepted
hitherto, at least two are represented. As
a result, the Dagzhuga Formation is considered
here to refer only to the Cenozoic
deposits and the Qiabulin Formation,
previously regarded as a synonym,
is resurrected to accommodate the Cretaceous
beds. These two formations
were juxtaposed by tectonic movements.
Our finding indicates that the stratigraphic
successions on the southern
Laurasian continental margin of Xizang
reflect changes from a deep forearc basin
through shallow littoral environments
to a mountainous landscape during
the Late Cretaceous and early Cenozoic.
This interpretation compares well
with those documented from the Gamba
and Tingri districts to the south of the
Yarlung Zangbo suture.
2010010568
云 南 罗 平 中 三 叠 世 大 凹 子 剖 面 牙 形 石
生 物 地 层 及 其 沉 积 环 境 研 究 = Conodonts
stratigraphy and sedimentary environment
of the Middle Triassic at
Daaozi section of Luoping County ,
Yunnan Province,south China. ( 中 文 ).
黄 金 元 ; 张 克 信 ; 张 启 跃 ; 吕 涛 ; 周 长 勇 ; 白
建 科 . 微 体 古 生 物 学 报 , 2009, 26(3):
211-224 3 图 版 .
罗 平 生 物 群 产 出 于 关 岭 组 二 段 , 该 段
大 凹 子 精 细 剖 面 细 致 的 沉 积 学 描 述 记
录 显 示 , 剖 面 岩 性 变 化 趋 势 为 : 从 生 物
扰 动 灰 岩 到 含 硅 质 结 核 的 条 带 泥 晶 灰
岩 ( 钙 屑 浊 积 岩 ) 向 白 云 岩 演 化 。 剖 面
详 细 的 牙 形 石 生 物 地 层 研 究 表 明 ,
176