Jurassic Macau | Study shows peninsula was formed 156m years ago, after Taipa, Coloane

A study co-conducted by the Institute of Science and Environment of the University of Saint Joseph (USJ) found that the once-islands of Taipa and Coloane were first formed between 162 to 165 million years ago. The Macau peninsula was said to have been formed later, between 156 to 157 million years ago.

The findings were based on ancient zircon crystals collected in the region that were formed during the Jurassic period, according to the researchers.

According to a geological study titled, “High-Precision Geochronology of Mesozoic Magmatism in Macao, Southeast China: Evidence for Multistage Granite Emplacement,” the mineralogical and whole-rock geochemical characteristics support the existence of two distinct groups of granites in Macau.

The researchers believed that these were emplaced in two pulses during the Upper Jurassic period.

“It is noteworthy that the Macau Jurassic granites are mostly biotite monogranites, as in other areas of Southeast China,” the study explained.

The research, which was initiated back in 2016 by Macau and Portuguese scientists, indicates that some areas, including Vale das Borboletas in Seac Pai Van, were only created less than 120 million years ago during the Cretaceous period, as granitic rocks were cut by volcanic dykes.

“Given the relatively short time span between the two pulses and the chemical similarity of the less evolved rocks, the observed differences in the evolutionary trends are probably the result of a change in magma evolution processes rather than in tectonic setting,” it added.

The tectonic setting was dominantly extensional related to the foundering of the “subducting paleo-Pacific plate under the Eurasian plate during the Middle to Upper Jurassic.”

Professor Ágata Dias from the USJ Institute of Science and Environment, who coordinated the research, explained to the Times that the study assists plate tectonic research in Macau. She noted that the data collected was the first of its kind. 

“This has relevance not only for history and knowing how Macau was formed, but also for geology. By knowing the age of the different places in the world and knowing how they were formed, we can better understand plate tectonics in general,” Dias told the Times.

“This is not just important for Macau, it is also important for South China and the rest of the world, in terms of what we know about plate tectonics,” added Dias.

The professor said that there would be another paper to be published explaining how Macau was formed in the following months. 

The study was funded by the Macao Science and Technology Development Fund (FDCT) and will be presented in the upcoming Goldschmidt Conference in Barcelona.

Additionally, according to the Cultural Affairs Bureau’s Cultural Heritage of Macao website, a large quantity of quartz and crystal flakes used for the production of quartz rings, semi-finished products and other tools were found in 2006.

The bureau said that the findings discovered in the excavations between 1973 to 2006 could lead to inferences that there was some human occupation in the island of Coloane during the Neolithic period, around 6000 years ago.