356
W. L. Watney . J. Kruger· J. C. Davis· J. Harff . R. A. Olea, . G. C. Bohling
trend of boundary Y continues to the southeast, forming the northern and
southern margins of several other regions. This continuing trend follows arcuate
gravity and magnetic anomalies. The eastern half of boundary Y also appears to
correspond to the northern margins of several large gravity highs that are probably caused by mafic intrusions. This boundary also appears to correspond
closely to the southern margin of several magnetic highs.
SAR Boundary Z resides in the southwest corner of Kansas in the heart of the
Hugoton Embayment, the site of significant current oil and gas development.
The northeastern part of boundary Z appears to follow northwest-southeasttrending gravity and magnetic lineaments, probably associated with both Central Plains Orogen and Southern Granite-Rhyolite Province structures. The eastern margin of this boundary turns abruptly to a southerly trend at the eastern
margin of a ring-like magnetic anomaly which is possibly associated with a caldera formed during evolution of the Southern Granite-Rhyolite Province. If this
truly is a caldera, its faulted margins, associated with the ring-like magnetic
anomaly, may have controlled the location of the eastern part of boundary Z.
The northern part ofboundary Z trends roughly east-west and may be roughly associated with the northern margin of several east-west-trending gravity and
magnetic anomalies. This northern part of boundary Z turns abruptly southward along the western margin of a prominent gravity high, probably created by
gabbroic intrusives.
The regional structure of the Precambrian basement appears to correlate with
the arcuate shape of the northern margin of the Hugoton Embayment and all
three of the SAR boundaries. X, Y, and Z, as well as the arcuate trends of the
gravity and magnetic anomalies, Precambrian basement configuration, and
Paleozoic structures including SAR boundaries. This suggests that Precambrian
structures were responsible for both the regional shape of the Hugoton Embayment and the trend of the regionalization boundaries.
The SAR boundaries vary in their orientation, and with the types of Precambrian features with which they correlate. The stratigraphic expression also varies spatially, depending on what spatial location and genetic set of which it is a
part. The causes of the SAR development are clearly related to basement heterogeneity and likely represent interactions with far-field stresses that influence
which basement element is reactivated. However, the correspondence of the SAR
with the gravity and magnetic lineaments is not always one-to-one, probably because of the often time-oblique nature of far-field stress orientation relative to
the orientation of basement structures.
6
Discussion
Phanerozoic sedimentary rocks form a thin veneer on the Precambrian basement in Kansas and, based on results of this study, show that their accumulation
is strongly influenced by differential subsidence associated with heterogeneities
in the basement. A geostatistical integration of thicknesses of six temporally dis-
W. L. Watney . J. Kruger· J. C. Davis· J. Harff . R. A. Olea, . G. C. Bohling
trend of boundary Y continues to the southeast, forming the northern and
southern margins of several other regions. This continuing trend follows arcuate
gravity and magnetic anomalies. The eastern half of boundary Y also appears to
correspond to the northern margins of several large gravity highs that are probably caused by mafic intrusions. This boundary also appears to correspond
closely to the southern margin of several magnetic highs.
SAR Boundary Z resides in the southwest corner of Kansas in the heart of the
Hugoton Embayment, the site of significant current oil and gas development.
The northeastern part of boundary Z appears to follow northwest-southeasttrending gravity and magnetic lineaments, probably associated with both Central Plains Orogen and Southern Granite-Rhyolite Province structures. The eastern margin of this boundary turns abruptly to a southerly trend at the eastern
margin of a ring-like magnetic anomaly which is possibly associated with a caldera formed during evolution of the Southern Granite-Rhyolite Province. If this
truly is a caldera, its faulted margins, associated with the ring-like magnetic
anomaly, may have controlled the location of the eastern part of boundary Z.
The northern part ofboundary Z trends roughly east-west and may be roughly associated with the northern margin of several east-west-trending gravity and
magnetic anomalies. This northern part of boundary Z turns abruptly southward along the western margin of a prominent gravity high, probably created by
gabbroic intrusives.
The regional structure of the Precambrian basement appears to correlate with
the arcuate shape of the northern margin of the Hugoton Embayment and all
three of the SAR boundaries. X, Y, and Z, as well as the arcuate trends of the
gravity and magnetic anomalies, Precambrian basement configuration, and
Paleozoic structures including SAR boundaries. This suggests that Precambrian
structures were responsible for both the regional shape of the Hugoton Embayment and the trend of the regionalization boundaries.
The SAR boundaries vary in their orientation, and with the types of Precambrian features with which they correlate. The stratigraphic expression also varies spatially, depending on what spatial location and genetic set of which it is a
part. The causes of the SAR development are clearly related to basement heterogeneity and likely represent interactions with far-field stresses that influence
which basement element is reactivated. However, the correspondence of the SAR
with the gravity and magnetic lineaments is not always one-to-one, probably because of the often time-oblique nature of far-field stress orientation relative to
the orientation of basement structures.
6
Discussion
Phanerozoic sedimentary rocks form a thin veneer on the Precambrian basement in Kansas and, based on results of this study, show that their accumulation
is strongly influenced by differential subsidence associated with heterogeneities
in the basement. A geostatistical integration of thicknesses of six temporally dis-