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|a (OCoLC)ocm26846167
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|9 AFU7039AM
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| 040 |
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|a TXA
|b eng
|c TXA
|d OCLCQ
|d OCLCF
|d OCLCO
|d OCLCQ
|d TXA
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| 035 |
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|a (OCoLC)26846167
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| 043 |
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|a ls-----
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| 049 |
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|a TXAM
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| 099 |
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|a 1991
|a Dissertation
|a D618
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| 100 |
1 |
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|a Divins, David Lee,
|d 1959-
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| 245 |
1 |
2 |
|a A tectonic history for cretaceous quiet zone crust in the South Atlantic Ocean /
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| 264 |
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1 |
|c 1991.
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| 300 |
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|a xiv, 166 leaves :
|b illustrations ;
|c 29 cm
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| 336 |
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|a text
|b txt
|2 rdacontent
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| 337 |
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|a unmediated
|b n
|2 rdamedia
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| 338 |
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|a volume
|b nc
|2 rdacarrier
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| 500 |
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|a Typescript (photocopy).
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| 502 |
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|b Ph. D.
|c Texas A & M University
|d 1991
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| 500 |
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|a Vita.
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| 504 |
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|a Includes bibliographical references.
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| 500 |
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|a "Major subject: Oceanography."
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| 520 |
3 |
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|a A tectonic history for crust of the Cretaceous Quiet Zone (KQZ) in the central South Atlantic is presented utilizing available geophysical data bases, primarily magnetic measurements. The most striking feature of the magnetic profiles across KQZ crust is the presence of high amplitude (~200-300 gammas) magnetic anomalies. This is an enigma since there are no observed reversals of the Earth's geomagnetic polarity for this time period. The explanation that is proposed for these anomalies in this study is their relationship to fracture zones identified in the KQZ. These fracture zones trend nearly parallel to synthetic flow lines that have been defined by previous investigators by matching conjugate seafloor spreading magnetic lineations. The magnetic anomalies associated with the fracture zones can be explained by the presence of bands of crust with either a thicker magnetic source layer or bands of crust with increased intensity separating areas of normal levels of magnetization intensity. Though other models, e.g. zero magnetization in the fracture zone valley or a source rock composed of material of low magnetization, may account for the magnetic anomalies, the above models best explain the observed anomalies. Poles of rotation were calculated from the fracture zone trends defined by the magnetic anomalies and seafloor spreading lineations, and from these rotations a tectonic history for the Cretaceous crust was developed. During the late Albian there was an easterly ridge crest jump of ~450 km. By the middle of the Cenomanian the following had occurred: (1) a second ridge jump to the west of ~150-200 km, and (2) the surface expression of the Tristan da Cunha hot spot had developed. Between the Turonian (~90 m.y.) and anomaly C34 time (84 m.y.) the initial ~450 km offset between segments of the Mid-Atlantic Ridge narrowed by a series of smaller ridge jumps and perhaps the initialization of a propagating rift system.
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| 650 |
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|a Geology, Structural
|z South Atlantic Ocean.
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| 650 |
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0 |
|a Geology, Stratigraphic
|y Cretaceous.
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| 650 |
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4 |
|a Major oceanography.
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| 650 |
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7 |
|a Cretaceous Geologic Period.
|2 fast
|0 (OCoLC)fst01352648
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| 650 |
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7 |
|a Geology, Stratigraphic.
|2 fast
|0 (OCoLC)fst00940727
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| 650 |
|
7 |
|a Geology, Structural.
|2 fast
|0 (OCoLC)fst00940775
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| 651 |
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7 |
|a South Atlantic Ocean.
|2 fast
|0 (OCoLC)fst01244523
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| 648 |
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7 |
|a From 65 to 140 million years ago
|2 fast
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| 655 |
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7 |
|a Academic theses
|2 lcgft
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| 700 |
1 |
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|a Rabinowitz, Philip D.,
|e degree supervisor.
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| 700 |
1 |
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|a Bryant, William R.,
|e degree committee member.
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| 700 |
1 |
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|a Carlson, Richard L.,
|e degree committee member.
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| 700 |
1 |
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|a Fahlquist, Davis H.,
|e degree committee member.
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| 700 |
1 |
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|a Sager, William W.,
|e degree committee member.
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| 710 |
2 |
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|a Texas A & M University,
|e degree granting institution.
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| 856 |
4 |
1 |
|x http://hdl.handle.net/1969.1/DISSERTATIONS-1274340
|z Link to OAKTrust copy
|t 0
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| 856 |
4 |
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|u http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=744883011&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD
|z Link to OAKTrust copy
|t 0
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| 994 |
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|a C0
|b TXA
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|a Texas A&M University
|b J.J. Pickle Campus
|c High Density Repository
|d Remote Storage
|t 0
|e 1991 Dissertation D618
|h Other scheme
|i unmediated -- volume
|m A14841035273
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| 952 |
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|a Texas A&M University
|b College Station
|c Electronic Resources
|d Available Online
|t 0
|e 1991 Dissertation D618
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| 998 |
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|a 1991 Dissertation D618
|t 0
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| 998 |
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|t 0
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