BASALT PLATEAU ESCARPMENT CRACK PATTERNS-FIELD, GIS AND ANALOG MODELING OF THE MCCARTYS FLOW AND IMPLICATIONS FOR MARS

Fluvial and volcanic features on Mars are often difficult to distinguish just based on morphological observations. A better understanding of the possible processes that form features such as cracks that are associated with undifferentiated flows on Mars might be helpful in determining the geological processes involved. The study of Earth analogs is one approach to better understand these features. The 3900 year old McCartys basalt is the youngest flow in the late Cenozoic Zuni-Bandera volcanic field in New Mexico (Dunbar & Phillips, 2004). The southern part of the flow includes numerous extensive plateaus with pits and surrounded by escarpments and mounds. Cracks are widely distributed, but are particularly prevalent where slope changes occur. Previous workers have attributed many of these features to the process of inflation, or the rising of an already solidified basaltic crust due to further magma injection from below (Mabery et al., 1999). The goal of this study is to quantify these features within the context of the inflation model through detailed field observations, GIS mapping, and physical modeling. We distinguished three types of inflation crack patterns based on shape, crack density and crack size, that are consistent over all of the McCartys’ escarpments. Physical modeling using polyethylene glycol 600 complimented the field observations and remote sensing and explored the inflation model by examining the formation of cracks through the lava inflation process. This study enhances our understanding of crack formation by lava inflation and may aid in the identification of lava flow processes on Mars.