Heterogeneity study of lacustrine source rocks relys heavily on a deeper understanding of the major controlling factors on their formation.Geochemical

petrological and sequence stratigraphy analyses of two sets of source rocks(K

1

sh and K

1

yc)in southern Changling Depression

Soliao Basin

reveal that multiple factors played roles in shaping the distribution of organic matters there.Al/Ti ratio was used to evaluate their paleoproductivity.Parameters like V/Cr

V/(V+Ni)

Sr concentration

Sr/Ba

and Sr/Cu as well as paleoclimatic indexes

were also employed to study their sedimentary settings.Results show that high-quality source rocks(mainly in upper Shahezi Formation)were developed in a highstand system tract and lacustrine transgressive system tract that featured in medium paleoproductivity

humid paleoclimate

low paleosalinity and low deposition rate.They are rich in Al

Ba

Cu

Cr

V and Ni

but lack of Mn and S.Meanwhile

low-quality source rocks(maninly found in the Yingcheng Formation)

were developed in lowstand system tract(LST)that was characterized by low paleoproductivity

semi-arid paleoclimate

high paleosalinity and high deposition rate.They are abundant in Co

Sr and V but lack of Al

Ba

Cr

Cu

Mn and Ni.We therefore suggest that

in the study area

(1)system tracts controlled the distribution of source rocks

(2)moderate-to-good primary productivity was a critical precondition for the development of high-quality source rocks

and(3)humid climate

low salinity as well as favorable sedimentation rate

were the reasons behind organic matter accumlations.