Publications

During the 1987-1988 austral summer field season, membersof the south party of the antarctic search for meteorites south-ern team* working in the Lewis Cliff/Colbert Hills region dis-covered several areas of unusual mineralization within theLewis Cliff ice tongue and its associated moraine field (figure1). The Lewis Cliff ice tongue (84°15'S 161°25'E) is a meteorite-stranding surface of ablating b

No abstract available.

No abstract available.

Stratigraphic relations and ten 14C ages show that movement occurred on the Meers fault in late Holocene time. Movement on the fault postdates the Browns Creek Alluvium, which began to be deposited between 14,000 and 13,000 yr B.P., and predates the East Cache Alluvium, which was deposited between 800 and 100 yr B.P. Surface warping along the fault led to local stream incision on the upthrown side

Two well-defined virtual geomagnetic poles (VGPs) for East Antarctica were obtained from the Middle Jurassic Ferrar Dolerite, sampled from a thick sill on Mt Schopf in the Ohio Range, and from a horizontal sheet intruding Paleozoic granitic rocks at Mt Cerberus in the Dry Valleys. The VGP from the sill at Mt Schopf lies at lat. 58°.0S, long. 129°.0W (dm=13°, dp=12°), and the VGP from Mt Cerberus l

The temporal sedimentary patterns in the Late Holocene central eastern and western Black Sea are very similar. The sedimentary history was most visibly affected by the coccolithophorid species Emiliania huxleyi which briefly invaded the Black Sea for the first time (“First Invasion Period”), nearly disappeared again shortly afterwards (“Transition Sapropel”), but returned permanently several centu

Geochemical analysis of the Lower Cretaceous Mowry Shale in Wyoming and Montana shows that organic matter type and reactive iron content limited pyrite formation during early diagenesis. Consequently, direct interpretation of paleosalinity cannot be made from a carbon/sulfur plot. Mowry Shale samples with hydrogen index (HI) less than 150 (mg hydrocarbon/ organic carbon) contain low amounts of sul

A chronosequence of calcic soils formed on granitic glaciofluvial terrace deposits of Rock Creek and the Clarks Fork in south-central Montana shows progressive replacement of aluminosilicate parent-material grains by calcium-magnesium carbonate. The terraces range from late Pliocene to Holocene in age as dated by tephrochronology, correlation, and stream incision rates. Replacement is first seen i

The Colorado province represents an addition of a belt of rocks more than 500 km wide to the southern margin of the Archean Wyoming craton during the Early Proterozoic, between about 1790 and 1660 Ma. Correspondence in ages between metamorphism, deformation, and plutonism; association of volcanic rocks with comagmatic calc-alkalic plutons; and lack of older basement are all consistent with the int

At two locations in the Atlantic Ocean (DSDP Sites 367 and 530) early to middle Cretaceous organic-carbon-rich beds (“black shales”) were found to have significantly lower δ15N values (lower15N/14N ratios) than adjacent organic-carbon-poor beds (white limestones or green claystones). While these lithologies are of marine origin, the black strata in particular have °15N values that are significantl

Fragments of Late Proterozoic ocean crust and mantle (ophiolites) occur within six major fault zones that mark sutures between crustal blocks (microplates) that were accreted between about 630 and 715 Ma to form the Arabian Shield. We report new U-Pb zircon ages for ophiolitic gabbro, diorite, and plagiogranite that range from 840 to 700 Ma and establish these complexes among the oldest proven oph

The Rocky Mountain region is one of the most topographically distinct and impressive parts of North America. The Rocky Mountains rise abruptly above the bordering regions, particularly on the east and northeast where they are flanked by plains, less so on the west and southwest where they are bounded by high plateaus. The Rocky Mountains comprise more than 100 individually named ranges that form a