Publications

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1999
Herbert, TD, Gee J, DiDonna S.  1999.  Precessional cycles in Upper Cretaceous pelagic sediments of the South Atlantic; long-term patterns from high-frequency climate variations. Special Paper Geological Society of America. 332:105-120. Abstract
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1995
Gee, J, Nakanishi M.  1995.  Magnetic petrology and magnetic properties of western Pacific guyots; implications for seamount paleopoles. Proceedings of the Ocean Drilling Program, Scientific Results. 144:615-630.   10.2973/odp.proc.sr.144.020.1995   Abstract

Despite the importance of seamount paleopoles in reconstructing past tectonic motions of the Pacific Plate, few data exist on the magnetic properties and processes of remanence acquisition in seamounts. We present a basic magnetic characterization and a detailed petrographic and microprobe study of the oxide minerals in mildly to strongly alkalic lavas recovered from five western Pacific guyots sampled during Ocean Drilling Program Leg 144. The Ti-rich chrome spinel compositions and Al- and Mg-enrich- ment in titanomagnetites reflect the alkalic nature of the lavas. The alteration history of these samples is diverse, ranging from low-temperature oxidation to highly oxidizing conditions resulting in an assemblage of magnesioferrite + titanohematite. The natural remanent magnetization (NRM) intensities for all five guyots are quite similar, yielding a combined arithmetic mean NRM intensity of 3.53 A/m, similar to previously reported values from dredged and drilled seamount material. The mean Königsberger ratio (9.8) implies an approximate 10% contribution of induced magnetization. Systematic discrepancies between the observed inclinations and inclinations derived from the magnetic anomaly data for Lo-En, MIT, and Takuyo-Daisan guyots are compatible with a significant bias from viscous and induced magnetization in these Cretaceous guyots.

1993
Gee, J, Varga R, Gallet Y, Staudigel H.  1993.  Reversed-polarity overprint in dikes from the Troodos ophiolite: Implications for the timing of alteration and extension. Geology. 21:849-852.: Geological Society of America   10.1130/0091-7613(1993)021<0849:rpoidf>2.3.co;2   AbstractWebsite

Paleomagnetic analysis of dikes from the Troodos ophiolite indicates the presence of a well-defined reversed-polarity overprint, an unexpected result given the currently accepted Cenomanian-Turonian age (88-91 Ma) suggesting formation during the Cretaceous Long Normal Period (83-118 Ma). This reversed- polarity component was apparently acquired prior to tectonic tilting of the dikes, implying that extensional tectonism occurred significantly (>5 m.y.) off axis. Alternatively, the paleomagnetic and field observations may be reconciled if parts of the ophiolite are significantly younger.

1991
Pospichal, JJ, Dehn J, Driscoll N, van Eijden AJM, Farrell J, Fourtanier E, Gamson PD, Gee J, Janecek T, Jenkins GD, Klootwijk CT, Nomura R, Owen RM, Rea DK, Resiwati P, Smit J, Smith GM.  1991.  Cretaceous-Paleogene biomagnetostratigraphy of sites 752-755, Broken Ridge; a synthesis. Proceedings of the Ocean Drilling Program, Scientific Results. 121:721-742.   10.2973/odp.proc.sr.121.181.1991   Abstract

Broken Ridge, in the eastern Indian Ocean, is a shallow-water volcanic platform which formed during the Early to middle Cretaceous at which time it comprised the northern portion of the Kerguelen-Heard Plateau. Rifting during the middle Eocene and subsequent seafloor spreading has moved Broken Ridge about 20°N to its present location. The sedimentary section of Broken Ridge includes Turonian-lower Eocene limestone and chalk with volcanic ash, an interval of detrital sands and gravels associated with middle Eocene rifting and uplift, and a middle-late Oligocene unconformity overlain by a thin section of Neogene-Holocene pelagic calcareous ooze. This paper summarizes the available post-cruise biostratigraphic and magnetostratigraphic data for the Cretaceous- Paleogene section on Broken Ridge. The synthesis of this information permits a more precise interpretation of the timing of events in the history of Broken Ridge, in particular the timing and duration of the middle Eocene rifting event. Paleontologic data support rapid flexural uplift of Broken Ridge in response to mechanical rather than thermal forces. Other highlights of the section include a complete Cretaceous/Tertiary boundary and an opportunity for first-order correlation of Paleogene diatom stratigraphy with that of the calcareous groups.

1988
Winterer, EL, Gee JS, Van Waasbergen RJ.  1988.  The source area for Lower Cretaceous clastic sediments of the Galicia Margin : geology and tectonic and erosional history. Proceedings of the Ocean Drilling Program, Scientific Results. 103:697-732.   10.2973/odp.proc.sr.103.181.1988   Abstract

Structural relations shown on seismic-reflection profiles of the Galicia margin indicate that during the Early Creta- ceous rifting of the margin, Galicia Bank and its southern extension (Galicia Ridge) were separated from the mainland of Iberia by a fault-controlled trough, and that the rift-stage sandy turbidite sediments in the fault troughs west of Gali- cia Bank were derived from the erosion of a narrow row of rugged hills that occupied the present area of Galicia Bank and Ridge. The volume and age span of rift-stage clastic sediments, estimated from drill and seismic data, imply rapid erosion of about 1 km of bedrock in the source area, suggesting that the source area was uplifted tectonically during the early stage of rifting. The composition of the sandstone indicates a source area dominated by granitic and schistose rocks, consistent with data from dredge hauls. The abundant fragmental plant debris in the sandstone indicates heavily wooded land, and regional sedimentological and paleobotanical data suggest warm rainy climatic conditions. A combi- nation of erosional lowering (largely compensated by isostatic rebound) and tectonic subsidence reduced most of the source area to sea level by the Aptian, and carbonate banks then flourished over the site of the former landmass.