Tectonic and climate control of oil shale deposition in the Upper Cretaceous Qingshankou Formation (Songliao Basin, NE China).pdf

Int J Earth Sci (Geol Rundsch) (2013) 102:1717–1734
DOI -013-0903-7
ORIGINAL PAPER
Tectonic and climate control of oil shale deposition in the Upper
Cretaceous Qingshankou Formation (Songliao Basin, NE China)
Jianliang Jia • Zhaojun Liu • Achim Bechtel •
Susanne A. I. Strobl • Pingchang Sun
Received: 29 November 2011 / Accepted: 21 April 2013 / Published online: 16 May 2013
Ó Springer-Verlag Berlin Heidelberg 2013
Abstract Oil shales were deposited in the Songliao Basin indicated by high gammacerane index values, low MTTC
(NE China) during the Upper Cretaceous period, represent- ratios, high b-carotene contents, low TOC/S ratios, and high
ing excellent hydrocarbon source rocks. anic matter Sr/Ba ratios. The stratified water column with anoxic con-
(OM) contents, a predominance of type-I kerogen, and a low ditions in the bottom water enhanced preservation of OM.
maturity of OM in the oil shales are indicated by bulk Moderate input of detrital minerals during the deposition of
geochemical parameters and biomarker data. A major con- the oil shale sequences is reflected by titanium concentra-
tribution of anisms and minor inputs from ter- tions. In this study, environmental conditions in the paleo-
rigenous land plants to OM input are indicated by n-alkane lake leading to OM accumulation in the sediments are
distribution patterns, composition of steroids, anic related to sequence stratigraphy governed by climate and
macerals. Strongly reducing bottom water conditions during tectonics. The first Member of the Qingshankou Formation
the deposition of the oil shale sequences are indicated by (K2qn1) in the Songliao Basin, containing the oil shale
low pristane/phytane ratios, high C14-aryl-isoprenoid con- sequence, passes a third-order sequence that can be
tents, homohopane distribution patterns, and high V/Ni divided into three system tracts (transgressive system tract—
ratios. Enhanced salinity stratification with mesosaline and TST, highst