Thursday, September 21, 2017

The Langhe Hills Landscape: The Messinian Salinity Crisis and the Tertiary Piedmont Basin

My previous post treated the Tertiary Piedmont Basin succession through the Tortonian. In this post I treat the sedimentation occurring during the Messinian period.

The Tethys Ocean separated Africa and Europe during the Jurassic and Cretaceous periods but was mostly eliminated as a result of the collision of the continents. Elements of this ocean survive today as the Mediterranean, Black, Caspian, and Aral Seas.
The Mediterranean Sea maintained its connection to the Atlantic and Indo-Pacific Oceans until early in the Miocene when it was reduced with the joining of the two continents along the Middle East front around 14 million years ago (mya). This joining of the two continents began a gradual change to a more arid Mediterranean climate.

The Mediterranean Sea connection to the Atlantic Ocean was maintained through various avenues (see figure below) until the closure of the Rifean Corridor in the early Messinian.

The closure of the Atlantic access precipitated a rapid environmental and climatic change driven by high evaporation rates in the Mediterranean Sea and the inability of riverine sources to replenish the water loss. This event is generally referred to as the Messinian Salinity Crisis and a rough timeline is as follows:

·       5.96 mya – Closure of the Rifean Corridor and partial dessication of the Red Sea
·       5.8 mya – Mediterranean almost dries out. Massive dessication leaves a deep, dry basin 3 to 5 km below sea level with a few hyper-saline pockets
·       5.5 mya – Less dry climatic conditions ensue resulting in more fresh water from the rivers. This fresh water progressively fills the basins and dilutes hyper-saline pockets into larger pockets of brackish water
·       5.33 mya – Zanclean flood. Strait of Gibraltar opens up, quickly filling the Mediterranean with water from the Atlantic Ocean. The end of the crisis.
As described in Progeo Piemonte (Climate variability and past environmental changes: lessons from the Messinian record of the Tertiary Piemonte Basin), “In less than a million years, deep sea sediments are replaced by shallow sea deposits, continental deposits, lacustrine sediments and eventually deep sea sediments.”
According to Nesteroff (The Sedimentary History of the Mediterranean during the Neocene), all of the Messinian deposits they encountered during their drilling explorations in the region “proved to be evaporitic species comprised of dolomitic marls interbedded with massive gypsum, anhydrite and halite.” On land, they found that, in the same period, The Tortonian blue marls were suddenly replaced by either evaporitic series or by lacustrine and continental deposits. The evaporitic deposits are primarily found in the deepest part of the sea but some fragments are found on margins that have been tectonically uplifted.
According to Progeo Piemonte, Messinian age rocks present in the Langhe describe a chronological sequence of the events associated with the Messinian Salinity Crisis:
·       Marls and Mudstones – rocks derived from deep sea sediments. These rocks record the alternation between a warm and humid climate and a cooler, less-humid one. Microfossils in the rock point to the exact moment when the Mediterranean weas cut off from the Atlantic.
·       Gypsum selenite and laminate – These minerals were formed in water with high salinity and point to an increased evaporation linked to the isolation of the Mediterranean Sea.
·       Sandstones and mudstones – Sediments deposited on the continent in low-salinity waters, rich in fossil vertebrate remains and shells of lacustrine molluscs. These remains testify to a savannah environment with temporary pools of fresh water.
·       Calcareous marl – These rocks tell the story of a re-established full connection between the Atlantic and the Mediterranean. These rocks are rich in marine planktonic microfossils recording a deep (around 800 m) marine basin.
·       Erosion surface – This surface describes an event of rapid dismantling of sediments caused by compressive tectonic forces.

©Wine -- Mise en abyme

Monday, September 18, 2017

Formation of the Langhe Hills landscape: The Tertiary Piedmont Basin

At the "end" of the Alpine orogeny, the area that is now the Langhe Hills did not exist in its current form; rather, it was a basin that rested beneath a remnant of the Tethys Sea. This basin -- the Tertiary Piedmont Basin (TPB) -- eventually became the repository for a sedimentary succession -- measuring 3000 sq km -- located at the junction between the southern section of the western Alps and the western termination of the northern Apennines (Mutti, et al., The Tertiary Piedmont Basin) and resting on wedges of both orogens. According to Mutti, et al., the basin rests on a segment of the wedge formed after the Alpine collosional event and was affected by the the growth of the Apennic orogenic wedge from the Oligocene on. Figure 1 below shows the TPB in relation to the major geologic structures of Northern Italy.

Figure 1. Structural sketch map of Northern Italy.
Source: Festa &Codegone, Geological Map of the 
External Ligurian Units ..., Journal of Maps 9, 2013.
The TPB is divided into three sectors -- western (Langhe). central, and eastern -- by the Celle-Sandia and Sestria-Voltaggio fault lines. The sedimentary succession, and underlying basement rocks, are present in all three sectors, as shown in Figure 2A below.

Figure 2: A - Deposits in the basin (Source: The Tertiary Piedmont
Basin, Mufti, et al); B - Age ranges in the Stages of the Miocene
 (Source: Wikipedia); C - Composition and depths of Oligocene
and Miocene deposits (Source: Mufti, et al)

The western sector basement rocks are Brianconnais units -- slices of European crust with a low-grade metamorphic imprint.

The central sector basement rock is of the Voltri Group, slices of oceanic suites composed of ophiolites (small pieces of oceanic crust that have been attached to the continent) and their sedimentary cover metamorphosed at high-pressure - low-temperature. This structure is generally credited with halting the eastern thrust of the Alps. The Sestri-Voltaggio line is the eastern boundary of the Voltri Group.

The eastern sector basement is comprised of Ligurian units, slices of oceanic suites composed of ophiolites and their sedimentary cover metamorphosed at low- to very-low-grade conditions.

Sedimentary Succession: Mid-Oligocene to Miocene
The TPB sedimentary succession began in the mid-Oligocene and continued through the Miocene. Figure 2A shows the population of sedimentations by geographic era while Figure 2C shows the types and extent of sedimentation exclusive of the Messinian period. The deposits through the Tortonian are predominantly terrigenous in natute -- that is, originating from land -- and are primarily sandstones and mudstones. At its deepest points the succession records a thickness of 6000 m (Mutti, et al.).

As the soils of note in the Barolo Zone derivs mainly from upper layers of the succession, we will confine the discourse in this post to those layers. Mutti, et al., suggest that the depositional settings evolved as follows:
  • Western sector troughs infilled with mixed terrigenous systems delta-fed from the Western Alps (Cortemalia and Lequio Units)
  • A shallow-marine domain, primarily consisting of southerly fed delta systems (Cessole and Serravelle Units) developed in the central and eastern sectors of the basin
  • A progressive uplift of the eastern and central sectors leading to the final infill of the basin with widespread southerly derived deltaic strata (Serravelle Unit)
  • During the Tortonian, these deltaic sediments experience a sudden regional drowning resulting in the deposition of progressively deeper-water and finer-grained strata (Sant'Agata Fossili Marl) and, eventually, chaotic deposits, indicating a tectonically steepened slope environment
  • These finer-grained slope strata encase re-sedimented coarse-grained and channelized bodies (Vargo Units) which are overlain by mudstones that grade upward to euxinic (black carbon-rich) shales
  • The latter are overlain by Messinian evaporites (not shown in Figure 2C and to be discussed in a later post)
The closure of the Straits of Gibraltar led to the Messinian Unconformity signaling the end of the Oligocene-to-Miocene succession. I will cover the Messinian Salinity Crisis in a follow-up post.

©Wine -- Mise en abyme

Wednesday, September 6, 2017

Tradition in Barolo: A visit to the Bartolo Mascarello cellar

The furniture and photographs of famous intellectuals, musicians, and artists adorning shelves laden with books were the same. Even the tiny sign embedded in the building's exterior near the door was the same. Although Bartolo Mascarello was no longer physically there, his presence was palpable as his petite daughter and only heir sat at the same desk where he had hand painted unique, prized wine bottle labels. In that small room where her father had welcomed clients for decades, Maria Teresa Mascarello opened the door for me onto her private life, if only a little.
So reads the opening paragraph of Suzanne Hoffman's Labor of Love, the seminal work on the wine family women of Piemeonte. And those were the words that rang in my ears as I prepared to enter into that room for my first visit ever to the estate.

I met Maria Teresa for the first time in June of 2016 at the Piemonte launch of Labor of Love.

Maria Teresa Mascarello and the author
at the June 2016 launch of Labor of Love
That was a special moment for me as I had participated in a Galloni retrospective (1958 - 2010) of the estate's wines just a little over a month earlier. At that meeting I had expressed my desire to visit the estate and she had responded with her card and the assurance that I would be welcome. I took her up on that promise during my mid-May-2017 trip to Piemonte. And now we were here.

My primary contact during the setup of the trip was Alan Emil Manley and this is who I asked for when we arrived. We were early so Maria Teresa's secretary sat us at the tasting table to await his arrival. On his arrival he indicated that Maria Teresa would be joining us shortly but he would be getting us started in the meantime.

Bartolo Mascarello was founded by Guilio Mascarello -- grandfather of Maria Teresa -- on January 1, 1920. Both Guilio and his father Bartolomeo were associated with the local grower cooperative but, using a 10,000-lire loan from a cousin, a loan underwritten by his father, Guilio left the coop to launch his own cantina. The business expanded in the 1930s with the acquisition of vineyard plots in Cannubi, San Lorenzo, and Rué. It was during this early period that the estate's guiding principles were enshrined in its practices (A Wine Atlas of the Langhe):
  • Wines made from grapes from a number of vineyards in order to drive consistent quality
  • No vineyard selections
Guilio's son Bartolo joined his father in the business after the end of WWII. Guilio died in 1981 at the age of 86 and Bartolo took over the running of the estate. In Bartolo's days, Mascarello blended vineyards, fermented the grapes together, and allowed the resulting wine to mature slowly. Bartolo died on March 12, 2005 and management passed to his daughter Maria Teresa.

In his preliminary remarks at the previously mentioned Mascarello tasting, Antonio Galloni stated that he expected the first flight -- themed "ready to drink" and including the 1995, 2000, 2003, and 2005 vintages -- to clearly exhibit the generational shift from Bartolo Mascarello to his daughter Maria Theresa. During her tenure, the aging time has been shortened, the winery (and the wine) has been cleaner, and they now have the equipment to do proper de-stemming. Maria Theresa got rid of the old barrels, she procured a modern de-stemmer, and the grapes are ripening such that it is easier to separate the Nebbiolo stem from the grape.

By this time Maria Teresa had arrived and she warmly greeted us. Given our lack of the Italian language, it was agreed that Alan would continue the discourse and cantina tour and Maria Teresa would re-join us when we returned to the tasting room.

Today the estate owns 5 ha of vineyards (distributed over four MGAs) and produces between 32,000 and 35,000 bottles of wine, 50% of which is Barolo. The characteristics of the MGAs in which the Mascarello plots are located are shown in the figure below. The characteristics of the individual plots are shown in the figure following.

The estate, according to Alan, is traditional in both its farming and cellar practices. They try to grow balanced fruit rather than going for "super" concentration. Nebbiolo is a vigorous vine and, as such, requires focused canopy and yield management regimes. In the case of canopy management, its utility as a tool in the battle against the effects of global warming also has to be taken into consideration. The vineyard architecture and cultural practices are illustrated below.

As we discussed the elements of the cellar, we walked through areas exhibiting very old bottles of wine as well as examples of Bartolo's well-developed and highly regarded wine labels.

Maria had written an article for Tong Magazine a few years ago in which she described the vineyard and cellar work required to make Barolo in the Mascarello style. I have summarized her writing on the cellar work in the figure below.

The goal, according to Alan, is to make a truly harmonious Barolo. And that task begins with the harvest date: we wait for the skins to tell us when to harvest. Further, there is a strict selection of the grapes that make it into the wine. That selection begins in the vineyard, where imperfect fruit is left on the ground, and continues with a second selection at the sorting table in the cellar.

Fruit from the four plots are mixed in the fermentation vats in a process called "asseblaggio." As the harvest time differs from vineyard to vineyard, recently brought in fruit is added to the mix that is already resident. According to Alan, "the ratios change from year to year as nature gives us different quantities from year to year. What the land gives us becomes our wine. We do not adjust the proportions to keep a constant ratio. For example, in 2012 we had hail only in Rué, and half the fruit was damaged and left on the ground. We simply had less of the Rué fruit in the mix that vintage ..."

The fermentation tanks are fiberglass-lined concrete tanks from the 1940s. The Slavonian oak barrels used in the aging process are changed out every 40 to 50 years. The aging regimes are as follows: Dolcetto and Freisa, 1 year; Barbera and Langhe Nebbiolo, 2 years; and Barolo, 3 years.

At the conclusion of the cellar tour we returned to the tasting room to sample the wines. We started with a Barbera 2014. This had been a difficult year with lots of rain. The weather cleared in the last two weeks of September and the first two weeks of October. The best wines of this vintage are excellent. Rose petal, spice, and rusticity on the nose. Good acidity and power.

Alan in the tasting room

Next up was the 2012 Barolo, This is a vintage, according to Alan, that they consider "shy" -- it requires a bit of coaxing. That year was never too hot, never too cool. They had hail in Rué and that is the vineyard that provides structure. Strawberries, honeyed nose, dried flowers, green herbs, sweet talcum powder. Delivers on palate. Fine-grained tannins. Lenghty finish.

Maria Teresa in the tasting room

The final wine tasted was the 2013 Barolo. This was a cool, classic vintage. After 21 days of maceration they terminated skin contact. Alan expects this wine to begin closing down temporarily sometime in the near future. Strawberries and roses. Honeyed nose with a hint of balsamic. Concentrated yet balanced. Lengthy finish. A wine to be aged and for the ages.

Alan and Maria Teresa

As we were going through the wines, Maria Teresa re-iterated the importance of her father's influence in everything that is done on the estate today. This adherence to his teachings is done both to honor him and because it continues to result in excellent wines that appeal to her customers.

Alan was a fount of information and a pleasure to be around if you like diving into the innards of a vat. We truly enjoyed this trip and would like to thank Maria Teresa and Alan for the hospitality and insights.

©Wine -- Mise en abyme