The 366 daily episodes in 2014 were chronological snapshots of earth history, beginning with the Precambrian in January and on to the Cenozoic in December. You can find them all in the index in the right sidebar. In 2015, the daily episodes for each month were assembled into monthly packages, and a few new episodes were posted. Now, the blog/podcast is on a weekly schedule with diverse topics, and the Facebook Page showcases photos on Mineral Monday and Fossil Friday. Thanks for your interest!

Thursday, December 18, 2014

December 18. Oil at Baku

The Caucasus Mountains, between the Black and Caspian Seas, hold one of the most important and early-produced oil provinces in the world. This area is part of the Alpine-Himalaya collision between pieces of Gondwana and the southern margin of Eurasia. Specifically, it’s the northern prong of Arabia that’s squeezing a small bit of continent, more or less part of the main Iran block, which itself was part of the Cimmeride continent, all that is being pushed into the south side of Eurasia.

Geographically, the Caucasus is taken as the boundary between Europe and Asia, and it contains some high mountain peaks, including Mt. Elbrus, a dormant volcano that reaches more than 5,600 meters above sea level, more than 18,500 feet. It last erupted about 2,000 years ago, showing that this area is still tectonically active.

Photo: Baku oil wells, Asbrink Collection.
One of the effects of the ongoing Alpine-Himalayan collisions was the development of fold belts along and within the Caucasus Mountains complex. Rocks of Miocene age were pushed into large asymmetrical folds, anticlines and synclines with strata arched upward and downward, respectively. This shows certainly that the tectonic action was going on after the Miocene rocks were laid down, since they are involved in the folding. This isn’t a surprise, since we know the collision is still going on today. The early Miocene rocks were probably folded in Miocene time, 5 to 20 million years ago, and in the Pliocene, 2 to 5 million years ago.

These anticlines trap lots and lots of oil. Oil was known in the area around Baku from the time of Marco Polo, and was supposedly used by locals for lubricants and fuel in the time of Alexander the Great. Baku oil was produced in quantity from hand-dug wells in the 1830s, and the world’s first paraffin factory began there in 1823. The first mechanically-drilled well in the world was drilled at Baku in 1846, 13 years before America’s first oil well in Pennsylvania, in 1859. By the 1870s, oil demand was surging worldwide, and outside investors came in to develop the oil fields around Baku. Two of the many fortunes that came from Baku oil were those of the Nobels, of Nobel Prize fame, and the Rothschilds. In 1900, half the world’s oil was coming from Baku, much of it from rocks of Miocene and Pliocene age.

Further west along the northern front of the Caucasus Range, additional fields were discovered. Grozny, in Chechnya, became Russia’s #2 source of oil until after the Revolution in 1917, and the Grozny area still produced about 7% of the Soviet Union’s oil as late as 1971. The Grozny field is in an anticline in Miocene rocks, with multiple sandstone reservoirs with impermeable shale seals. The Caucasus oil was a major target of Hitler’s forces in World War II, and it still plays a significant role in the geopolitics of the region.

Pliocene deltas (that form oil reservoirs)
coming into the South Caspian Basin.
From USGS Bulletin 2201-I
It’s no surprise that this oil was found so early, because it is practically at the surface in many cases, or just a few feet beneath the surface in the relatively young Miocene and Pliocene rocks. Marco Polo reportedly saw a natural gusher of oil. The organic rich source rocks are largely of Miocene age, called the Maykop Suite. There was a restricted seaway extending through this region, on the north side of the approaching continental blocks before they collided to raise up the Caucasus, and the marine carbonates of the Maykop Suite were deposited there. By Pliocene time, just four or five million years ago, the region became isolated from the sea, and rivers brought sandy sediment into the basin. Some of the most productive reservoirs around Baku are from Pliocene rocks deposited in deltas around the margins of the South Caspian Basin, which is an entrapped bit of old Tethys Ocean floor. The ongoing tectonic activity has created plenty of traps for the oil. 

Azerbaijan, where Baku is located, still produces about 900,000 barrels of oil per day, about 10% of what the US produces. But it’s only about the size of the state of Maine.

—Richard I. Gibson

Cenozoic oil – Azerbaijan 
Photo: Asbrink Collection.

Pliocene deltas (that form oil reservoirs) coming into the South Caspian Basin. From USGS Bulletin 2201-I, by Linda Smith-Rouch, 2006.

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