IMAGING THE CHEYENNE SUTURE AND JEMEZ LINEAMENT USING COMMON CONVERSION POINT STACKS OF RECEIVER FUNCTIONS FROM THE CD-ROM DATASET

For twelve months from May ‘99 to May ’00, two portable broadband PASSCAL teleseismic line arrays where operated as part of the CD-Rom experiment. The primary targets of these lines were to image the lithospheric structure that surrounds the Cheyenne Suture and the Jemez Lineament. From this data we have been able to make approximately 1200 useful receiver functions out of ~100 events with magnitude >5.5. Using these receiver functions we constructed an image of the Moho using the common conversion point stack technique. The major observations provided by these images are: on the southern line, the Moho has no more then 5 km of topography with a slight wobble in the vicinity of the Jemez Lineament. On the north line we get about 10 km of crustal thickening (40km to 50km) south of the Steamboat Springs. At the Cheyenne Belt (~41.25 deg N) we see an offset in the Moho. North of the Cheyenne Belt we see along transect deformation in the Moho along with the occurrence of a strong mid–crustal reflector. Comparing these results with previous and ongoing experiments that examine the Cheyenne Belt we observe several re-occurring features. The lateral deformation in the Moho located north of the Cheyenne Belt is consistent with deformation that is imaged in the Lodore and Deep Probe passive experiments. The crustal thickening in the Northern Colorado Rocky Mountains is consistent with the crustal depths of 50km observed by the PASSCAL Rocky Mountain Front experiment. The mid-crustal reflector and the disappearance of the Moho signature under the Cheyenne belt are consistent with the active reflection profile that images strong mid-crustal reflectors just north of the point they can no longer image the Moho. Using these results and the results of currently ongoing and future work we should be able to constrain the lithospheric processes that lead to continental formation.