| Taking the drilling cores of the 10th rhythmite of Eq3
4 Submember(Eq3
4
-10 rhythmite) and 5th rhythmite of
middle Eq4
0 Submember(Eq4
0
-5 rhythmite) of Qianjiang Formation in Wangchang anticline as main research object, the
provenance properties and sedimentary environment of different rhythmite in Qianjiang Depression were studied through
the analysing of XRD and ICP-MS. The results show that there are obvious differences in mineral composition, REE
content and distribution between the two rhythmites. Clay minerals and quartz are the main silicate minerals in Eq3
4
-10
rhythms, while plagioclase, clay minerals and quartz are the main silicate minerals in Eq4
0
-5 rhythmite.The contents of
REE and silicate minerals of the two sets were positively correlated. The REE fractionation degree of clastic rock in Eq3
4
-
10 rhythmite is higher than that of carbonate rocks, while that of clastic rock in Eq4
0
-5 rhythmite is similar to that of
carbonate rocks. It is indicated that the provenance of these two rhythmites is different, or the climate is relatively warmer,
humid and wind erosion is stronger in the depositional period of Eq3
4
-10 rhythmite. The sedimentary water of these two
sets of strata are in reductive environment, and the lake water may be deeper during the deposition period of Eq3
4
-10
rhythmite, which is more conducive to the accumulation and preservation of organic matter. Therefore, it is inferred that
Eq3
4
-10 rhythmite has more exploration potential. |
