ABSTRACT

The Humble Oil and Refining Company, H. J. Ellender No. 1, sec. 32 T. 19 S., R. 19 E., Lirette field, Terrebonne Parish, Louisiana, is the type locality for Bigenerina nodosaria directa, Cibicides carstensi, Uvigerina lirettensis, Globorotalia fohsi fohsi and Globorotalia mayeri, stratigraphically important Miocene marker species described by Cushman and Ellisor (1939). Globorotalia fohsi fohsi, ranging in the Gulf Coast from the Cibicides carstensi opima Zone upward through the Bigenerina humblei Zone, has been used extensively throughout the world for purposes of intercontinental correlation of Miocene deposits.

Ellisor (1940) reported Bigenerina humblei. Uvigerina lirettensis and Globorotalia fohsi fohsi at 9,612 feet, the sample depth from which she and Cushman had earlier described Globorotalia fohsi fohsi and Globorotalia mayeri. Additional deeper drilling and later work have proved that the Humble, Ellender No. 1 penetrated beds no older than the Bigenerina nodosaria directa-Cibicides carstensi Zone. The deepest well in the Lirette field, the Humble, H. J. Ellender No. 6 (also located in sec. 32), drilled to 13,500 feet, did not reach the Textularia stapperi Zone which overlies the Bigenerina humblei Zone.

In order to establish the point that Bigenerina humblei could not have occurred at 9,612 feet in the Lirette field, and that the Humble, Ellender No. 1 should not be considered a valid type locality for Globorotalia fohsi fohsi and Globorotalia mayeri, cross section A-A has been constructed to illustrate correlations between Raceland field, Lafourche Parish, and Bay Baptiste field, Terrebonne Parish. The section depicts the general downdip (coastward) thickening of the Miocene section and the tremendous sedimentary accumulations encountered on the downthrown sides of the large growth or depositional faults typical of the area.