Accretionary Wedge: Back in time

July 19, 2009 at 21:01 | Posted in accretionary wedge, geologic time, geology, nigeosyncline, Nigeria, Uncategorized | 3 Comments

The June edition of the Acrretionary Wedge geoblogospheric carnival was hosted at outside the interzone. I’m obvious late as usual but the topic was too intriguing to so here i am with a one month late. the intruiging post is

“Where and when would you most like to visit to witness and analyze an event in Earth’s history”

Actually if I had a time machine I would go through the whole of geologic time on the spot where I’m on (Nigeria) to see how the land I live on has changed through time. But to narrow down I’ll go for the cretaceous when the Benue trough was evolving. there are still a few important questions to be answered:

  • Is the Benue rift a failed arm of an R-R-R triple junction formed at the early stages of the opening of the Atlantic (similar to the red sea-afar triangle) or is as a result of transcurrent movement along the chain and chacourt transform faults?
  • How extensive were the various trangressions in the area? Did all transcontinental connections between the Tetys and the Atlantic exist?
  • What caused the Santonian compression and it’s accompanying magmatism?

I’d also like to see the sedimentary environments where the formations of the Benue rift and the adjacent Anambra basin. And many more things.

The images are from here>

Where I'm talking about, 120 million years ago

Where I'm talking about, 120 million years ago

Where I'm talking about, 105 million years ago

Where I'm talking about, 105 million years ago

Where I'm talking about, 120 million years ago

Where I'm talking about, 120 million years ago

Where I'm talking about, 65 million years ago

Where I'm talking about, 65 million years ago

I’d also like to see Nigeria during the Pan- African orogeny (650-500 million years ago) to see how it happened and how those intrusions which stand out as the inselbergs I blog about earlier formed.

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THE LEGEND OF THE 7 LAKES: EPISODE 2- The Excursions

July 18, 2009 at 12:37 | Posted in 7 lakes, Nigeria, petroleum, Uhere | 1 Comment
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This is the second of installment of my encounter with the lakes of Opi in Enugu state. For the first part of the series see here.

In 2006 some friends of mine from the residence (Uhere Study Centre) went on an excursion to discover the lakes and reached the Uhere River. The locals also confirmed the existence of one or two lakes in the region but they were not able to visit due to lack of time. At that time I discovered Google EarthTM and went scanning the area but without high resolution images of the area available from Google Earth at the time I had to be content with noticing ‘black areas’ which I could not use to prove to more skeptical fellow residents in the house at the time that there were lakes in the area.highs school lakes

I got my chance to see the lakes with my own eyes in 2007 on another excursion with a group of high schools students. We reached Uhere River, after walking nearly 3 hours from Opi junction and locals who were mining Ajali sands from the river bed told us again of the ‘nearby’ lakes and of the crocodiles and blood sucking leeches and also of some ‘white men’ who went there to take measurements a long time ago. I also got hints on that trip which should have removed my ‘geological’ objections: The dirt road down to the river was fairly steep eastwards. And around the river I observed mudstones and siltstones units which seemed to be directly under the cross-bedded friable sands.

River Uhere offered nice exposures of the cross-bedding characteristic of the Ajali formation therefore I had another excuse to go there again when I suggested the river as a good location for first year geologists to go on a field excursion to see the results of sedimentary processes in October of 2007. My classmate Ndubuisi Obi (who went with me on the last excursion and with whom I had long amateur discussions on the geology of the lakes) and I were guides for the students and a lecturer on an excursion to the river with the personal intention of seeing the lakes. At the time all my doubts of the existence of the lake had been dispersed when people of the residence encountered the lakes on an earlier excursion while I was 300km away in another field location working on my B.Sc. project. Sadly they returned without pictures of the lake as rain had spoiled the only camera they were with. This trip with the freshers was therefore a question of satisfying that urge (common to all geologists) to see for oneself what others have seen. That urge wasn’t satisfied on the trip as due to problems of communication with the locals we were misled and did not find the lakes ( though if it were not for the need to return to school on time we should have found them).

Sadly that was at the tail end of my undergraduate days in the university and I had to leave Nsukka for Ibadan (500km away) for compulsory National youth service but with the dream of one day finding seeing the lakes.

The L’Aquila Quake and a Lucky Country

April 8, 2009 at 11:12 | Posted in Earthquake, Italy, Nigeria | 3 Comments
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I’ve been following, like everyone else, the sad events following the magnitude 6.3 earthquake that has already killed more than 200 people in Italy. I feel for those affected by another instance of natures power of man.

In discussions about quake with friends conversation usually comes to what would happen if Nigeria was as earthquake prone as say Indonesia, Algeria, Iran or Japan. The conclusion is that we are a very lucky country. the worst I’ve heard (but not witnessed) is the tremors in Ibadan in the 80’s. Looking at buildings in Ibadan for instance it scares me to imagine what a 5.0 magnitude earthquake would do. The same can be said for almost all the major towns in Nigeria. In Lagos there are  stories of building collapsing on their own almost every week with the number of people flocking  to the city, and house owners  looking for how to save money, or the building contractors looking for ways to get more profit by shortchanging their clients in terms of quality of work.

If more than 200 people  are dead and  thousands made homeless as a result of a 6.3 magnitude quake in a country known (at least here) for the quality of their buildings, then I can only say that we are very lucky here- tectonically.

THE LEGEND OF THE 7 LAKES: EPISODE 1- The Legend

March 14, 2009 at 09:20 | Posted in 7 lakes, geology, Nigeria, UNN | 5 Comments
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It all began with my first visit to a University hall of residence and Study centre for students with a funny name: Uhere. ‘What kind of name is that?’ I asked. I was told that it is the local dialect’s word for wind. I was also told that the centre is named after a river somewhere around. That was in my first undergraduate year (2003). A year later, I became a resident at the center and we one day had a get-together with a lecturer from the department of tourism at the university. He told us, among many other things, about some tourist locations in Enugu state and mentioned Uhere River and The seven lakes of Opi. I was a bit skeptical about their existence, with ‘geological’ reasons for my doubt. The Nsukka area sits on the late cretaceous (Maastrichian) Ajali Sandstone formation (a.k.a false-bedded sandstone), consisting of characteristically friable cross-bedded sandstones. Ajali formation is also a good aquifer, supplying water to the areas around Nsukka all the way down to Enugu (city) area and even Okigwe. In Nsukka the groundwater level is deep (more than 100m on average) and if it is the same in Opi which is close to Nsukka (about 10 km to the southwest), how would the lakes be able to hold water on such a porous and permeable formation?

Accretionary Wedge: Inselbergs of Nigeria

February 17, 2009 at 09:11 | Posted in accretionary wedge, geology, Granite, Inselberg's, nigeosyncline, Nigeria | 9 Comments

This month’s Accretionary Wedge Geosblogospheric carnival is hosted at Geotripper and the theme:

What are the places and events that you think should all geologists should see and experience before they die? What are the places you know and love that best exemplify geological principles and processes?

Since I’m a new in the geoblogosphere I figured that I take part.

There are many impressing geological features in Nigeria though the general awareness of these features by the general public leaves much to be desired. of these feature one of the most prominent and indeed awesome are the Granite inselbergs.Granite inselergs can be found in the areas of the basement complex which covers more than two-thirds of the country. Here are some of the most popular ones

Zuma Rock, Abuja, central Nigeria

Zuma rock Abuja Central Nigeria. View from the west

Zuma rock Abuja Central Nigeria. View from the west

The most famous (Nigeria’s Ayer’s) and one of the largest at more than 1km across.


Idanre hills, Akure South west Nigeria

Idanre hills (Idanre town in the foreground)

Idanre hills (Idanre town in the foreground)

Another famous one which has made the small town in the foreground a tourist destination.
Kwantankwashi hill, Zamfara North Central Nigeria

kwatankwarshi Inselberg-

kwatankwarshi Inselberg

Wase rock, wase North east nigeria

wase

Wase inselberg

Kajuru ludo hill, Kaduna Nigeria

Kajuru-Ludo hill

Kajuru-Ludo hill

There are many more even outstanding examples in other parts of the country and is something that one cannot miss on any jurney around the nigeria.

The granite inselbergs are huge plutonic intrusions that were emplaced during the pan-african orogenic event which affected all of what is now Nigeria, most of africa and even the arabian peninsular and brazil (sugar loaf mountain). Though they were emplaced at depth 550 million years of erosion have brought them to the surface where the stand out due to their greater resistance to erosion than the surrounding migmatites , Gniesses and migmatic Gniesses.They dome shapes are result of exfoliation (a Chemical weathering process that peels away layers of rock).

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