Baiyun Sag,located in the southwestern Pearl River Mouth Basin,is a transfer zone in Cenozoic.The well BY7,in the vicinity of the boundary fault of Baiyun Sag,records multi-stage magmatism.The basalt-andesitic lavas(sample BY705~BY706) and basalts(sample BY701 ~ BY704) found in well BY7,belong to Enping Formation and Zhujiang Formation,respectively.They record two magmatic activities which took place in pre-opening of South China Sea(SCS) and in the late stage of SCS formation.Geochemically,in the volcanic rocks of Enping Formation,contents of SiO2(53.60% ~ 54.21%) and(Na2O+K2O)(4.63%~5.16%) are different from the volcanic rocks of Zhujiang Formation which are with lower SiO2(47.26% ~ 52.34%) and higher total alkalis(5.93% ~ 6.98%).All volcanic rocks are characterized by low total REE contents(∑REE=153.0 ~ 174.3 ppm) and strong differentiation between LREE and HREE((La/Yb)N=10.1 ~ 13.5).The REE distribution patterns and trace elements spider diagrams of these volcanic rocks are similar to the ocean island basalt(OIB).Evidences of lithospheric involvement are exhibited from the investigation of these volcanic rocks,including enrichment in large ion lithospheric elements(Rb,Ba,Ka),high Pb content and low value of Nb/U.Crustal component,resulted from lithosphere delamination which is induced by crust-mantle interaction during late Cretaceous,involves in magma generation,which is the cause of crustal contamination.Magma is generated in a mantle plume or hotspot environment and originated from enriched mantle source of low-degree partial melting.Volcanic rocks of Enping Formation may be caused by the upwelling of deep mantle with an OIB-MORB type magma,and experience the metasomatism of fluid released from subduction slab and crustal contamination.Volcanic rocks of Zhujiang Formation belonging to intraplate alkaline basalt,consist mainly of an EMI-type OIB end-member mantle source and have crustal contamination,probably are caused by upwelling of Hainan mantle plume.Deep mantle upwelling may play an important role in the incipient period and the following evolution of South China Sea.

Fission-track(FT) thermochronology is a low-temperature dating technique utilizing the damage property produced by uranium fission decay.As the advanced researches of annealing behavior,and laboratory annealing models,this technique,especially apatite fission-track,has become an important measure to constrain the thermal history of sedimentary basin.Among three main apatite fission-track annealing models proposed by Laslett et al.(1987),Crowley et al.(1991) and Ketcham et al.(1999),respectively,the last one is the most significant and widely-applied annealing model,which integrated the influence of time,temperature and chemical composition to various types of apatite,together using the c-axis projected track-length and Dpar.This apatite multi-kinetic fission-track annealing model by Ketcham et al.(1999) can be applied well to make thermal modeling,describing the temperature-time relation in the development of basin.Zircon FT,(U-Th)/He,apatite(U-Th)/He,Ro value,surface temperature,and stratigraphic age are all as constraints for fission-track thermal modeling,while the HeFTy(2009) is an excellent software for reconstruction of low-temperature thermal history.

Pot experiments of two cultivars lentils were treated with soil drying at four-six leaves under different planting models,then MDA,Pro content and biomass in leaves of lentil were measured.The experiments indicate that MDA and Pro content increase gradually with the increase of drought stress time,and MDA and Pro content under drought-stressed are higher than those under well-watered after water treatment.The variety of MDA and Pro content are distinct between two plantings.At monoculture,MDA and Pro content are close to each other;at mixture,MDA content of Longquan's is higher than Qingshui's,but the content of Pro is lower.The shoot dry weight and grain yield of Qingshui are higher than those of Longquan's at different treatment,so the water use efficiency of Qingshui is higher than Longquan's.The experiment shows the capacity of escaping drought of Qingshui is better than Longquan's,and the mixture is more suitable than monoculture to Qingshui,but the monoculture is more suitable than mixture to Longquan.