Cryptomare Identification And Its Formation Evolution Analysis On Lunar Surface

Since the 1970 s,scientific researchers have studied Dark halo crater(DHC)and dark spot on the lunar surface.Cryptomare,marked the ancient activity of basalt,is basalt deposit of lunar mare covered by either basin or impact crater ejection.It is a key scientific problem to understand heat evolution and volcano history of the moon and to reveal convection on lunar mantle and solidifying magma of the moon.Up to now,there are a few studies about cryptomare,to say nothing of internal research.At the earliest,scholars abroad identify areas that cryptomare exist possible by observing DHC.With the increase in resolution of remoting sensing image,it corrects and clears continuously about the area that cryptomare may exists.This paper analyzed the DHCs in the study area of Balmer,Cleomedes,Dewar,Mendel-Rydberg and Milne,and combine mineral analytical method to identify the distribution of cryptomare.Based on the identification of cryptomaria,this article analyzed the evolution of Balmer cryptomare formation process,combined with the data sets about the age,the stratum,the terrain and the like.Considering its features and the form of expression,the author analyzed the criteria and techniques of distinguish it in details corresponded to the features that cryptomaria have.The writer contrasted and analyzed the main identification basis,Dark Halo Craters(DHC),and secondary basis such as spectral mixing analysis,geochemical element,light plains,the location of the basin,the known maria,mascons,and the source of obscuring agents to distinguish cryptomare.DHC is the most important evidence for determining the existence of cryptomare.The author analyzed study areas by using spectra image dataset,reflection,the optical maturity parameter and spectral absorption characteristics of DHC dark rings.And then the writer got DHCs in research area and determined the existence of cryptomare.Cryptomare,whose main ingredient is pyroxene whose absorption peak at both 1um and 2um,is ancient volcano deposit.In order to identify range of cryptomare,the author obtained Integrated Band Depth image of mineral at both 1um and 2um,and combined reflectance image at 1489 nm to composite false color image based on M3 data.Then used LP-GRS Th,Fe O and terrain data sets achieve the purpose.In order to analyze process of cryptomare formation,the writer chose the Balmer cryptomare,parted homogeneous geological unit by using clementine color ratio mix image.Using CSFD method measured its age between 3.84 Ga and 4.07 Ga,combined with terrain and stratum relationship analyzed formation of cryptomare,drew a conclusion that the evolution of the Balmer cryptomare formation was divided into the impact basin formation,the impact basin filled by the early volcanic eruption,light plains which covered by impact ejecta of the Imbrium impact event and DHCs formed by the underlying basalt emplaced on high reflectance material.