PALYNOLOGY FROM A FOSSIL PLANT-BEARING INTERVAL IN THE STOCKTON FORMATION, TYLER STATE PARK, BUCKS COUNTY, PENNSYLVANIA

Fossil pollen and spores are analyzed from a rare dark-gray shale in the Triassic-aged Stockton Formation exposed within Tyler State Park, Bucks County, Pennsylvania. This sample is collected from the middle member of the Stockton Formation – a dominantly grayish red, fine to medium grained sandstone unit with subordinate red mudstones and conglomerate. Palynomorphs from the sample indicate an age of Middle to Late Carnian. A non-marine, swamp margin paleoenvironment is interpreted based on the abundance of wood fragments and pollen, and the lack of marine palynomorphs. Furthermore, vitrinite reflectance (%Ro) is estimated from the spore color at approximately 1.48 percent and implies a maximum temperature that the palynomorphs were exposed of 167°C. A burial depth of 2960.7 m is estimated based on this Ro and an assumed geothermal gradient of 34.5°C/km. This depth assumes the maximum temperature was not elevated by any of the regional diabase intrusions. This assumption is likely valid due to the absence of diabase in this portion of the study area, however, circulation of hot fluids via faults and joints cannot be ruled out.

Pollen flora identified include 75 spore/pollen indeterminate, 2 Alisporites opii, 1 Alisporites parvus?, 3 Alisporites? sp indeterminate, 1 Aratrisporites? sp, 5 Bhardwajispora jansonii, 1 Cycadopites reticulatus,1 Enzonalasporites vigens, 3 Patinasporites densus, 1 Pityosporites chinleana, 1 Pityosporites cf sp B Robbins 1981, 1 Pityosporites oldhamensis?, 1 Pretricolpipollenites cf ovalis, and 1 Psophosphaera sp (alga?).