Hello. I need a reworded summary of the following text. The geologic features of
ID: 288375 • Letter: H
Question
Hello. I need a reworded summary of the following text.
The geologic features of the Virgin Spring area record four major deformational events. The first, occurring as early as 1,700 Ma, accompanied and followed the metamorphism of the crystalline complex. It contributed to the angular discordance between planar and linear features in the complex and bedding planes in the overlying later Precambrian sedimentary units. The second began with the deposition of the arkosic conglomeratic strata low in the Crystal Spring Formation and continued through Noonday time (Fig. 3), spanning a poorly bracketed interval of time that probably lasted about 400 m.y. This event was accompanied by vertical crustal shifts (Wright and Troxel, 1984) causing facies changes in the Pahrump Group and Noonday Dolomite, and the angular unconformity beneath the Noonday. These features, as expressed in the Virgin Spring area, indicate the presence of a major Precambrian discontinuity. We interpret fold like features preserved in the later Precambrian and Cambrian sedimentary rocks as actual folds forming before intricate faulting that produced the chaotic appearance of the Pahrump and younger units. We suggest that this folding occurred in Mesozoic or Early Tertiary time. We continue to attribute the formation of the Virgin Spring and Calico phases of the chaos, the fourth deformational event, to faulting related to crustal extension in Cenozoic time. When the Death Valley region was deeply eroded, within the late Mesozoic-early Cenozoic interval, and then severely extended in later Cenozoic time, the resulting pattern of faulting led to the illusion of a single Cenozoic dislocation surface, originally planar and later folded.
To our earlier interpretations that related the telescoping of the later Precambrian and Cambrian strata in the chaos largely or wholly to movement on normal faults, and that involve the underlying crystalline complex in the chaos-related faulting (Wright and Troxel, 1973), we add the following interpretations. (1) The complex and younger cover rocks have responded differently to severe crustal extension, thus creating the appearance of a single Tertiary thrust fault bringing the younger units over the complex without involving the complex. The complex has been broken and extended by normal faults. (2) The chaos-forming event has consisted of a continuum featured by normal faulting accompanied by intervals of erosion, basinal sedimentation, and volcanism, Thus, the Virgin Spring phase of the chaos is more intricately faulted than the Calico phase and the Calico phase more so than the Funeral Formation. (3) The high-angle faults of apparent lateral slip we interpret as genetically and temporally related to the normal faults.
Explanation / Answer
There are four major deformations that can be interpreted in order to establish the geological setting of the Virgin spring area. These are recorded as follows-
The earlier interpretations were made out by telescoping the later Precambrian and Cambrian strata in the movement of the normal faults which involves the underlying crystalline complex in the chaos related faulting. The additional information that were made out are as follows-
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